Bachelor of Science in Biotechnology

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Isolation and screening of azo dye reactive violet 5R degrading bacteria from textile sludge
(1/24/2016) Ahmed, Hasan Hasnaeen; Siddique, Ms. Romana
Azo dyes account for the majorly produced synthetic dye substances in industries. They are extensively used in the textile, leather, pharmaceutical and cosmetics industries, posing a threat to all life forms. Harmful chemicals are consistently used in the dying process. These include dioxin, toxic heavy metals such as chrome, copper, zinc and formaldehyde. These are proven to be potential carcinogens. The dyes also adsorb and reflect the sunlight entering the water, thereby interfering with the aquatic species growth and hindering photosynthesis. The solution to these remedies are generally available within the environment. There are certain microorganisms which have the ability to degrade these azo dyes. In this study three bacterial strains, Streptococcus equi subsp. zooepidemicus, Brevibacillus centrosporus, Paenibacillus azoreducens, have been extracted from the sludge samples collected from Ridesha Textile Industry, Bhaluka. ABIS microbiology software (Advanced Bacterial Identification Software) was used to justify and determine the identity of these bacteria with the aid of results obtained from the biochemical tests that were undertaken. They have remarkably reacted to the azo dye Reactive Violet 5R. They have decolorized this dye with each of them producing unique results. The decolorization rate differed for every organism inoculated into the azo dye, reactive violet 5R. This decolorization rate was also different for the various concentrations of the same dye. Brevibacillus centrosporus displayed a decolorization rate of 94.55%, 90.79%, 91.17% when inoculated and incubated in an SM broth containing the azo dye reactive violet 5R at 1% (v/v), 3% (v/v), 5% (v/v) concentrations for a consecutive 5 days. Paenibacillus azoreducens projected a decolorization rate of 85.63%, 86.48%, 38.81% for the respective concentrations, 1% (v/v), 3% (v/v), and 5% (v/v) of the azo dye reactive violet 5R. Streptococcus equi subsp zooepidemicus produced intriguing results where the decolorization rates were 67.78%, 21.69%, 40.10% for the respective concentrations 1% (v/v), 3% (v/v) and 5% (v/v) of the azo dye reactive violet 5R, but the rate of growth of this organism in the SM broth media was much higher as proven by the absorbance rates achieved in the consecutive 5 days of inoculation and incubation. The organisms obtained after conducting this study can be used as a biological consortia for the treatment of the textile effluents. In the future, the genes responsible for the dye degrading characteristics can be isolated from their hosts and with the help of recombinant technology it
Isolation of reactive Red 3BX and Yellow 4GL dye degrading bacteria from the textile sludge
(BRAC University, 11/23/2015) Fahim, Ahmed Abdullah; Siddique, Ms. Romana
This world is getting polluted in different ways. This world has many prime components including soil, water, and air. Every day to meet human needs thousands of mills, factories and are producing necessary commodities. And they are polluting the environment in different ways. Some factories are emitting poisonous gases, some are discharging effluents and liquid waste in the environment which are creating hazardous problems in the water system and in soil. And for this environment pollution one of the prime causes is discharging textile dyes into the environment without treatment. This is a common problem for many countries as well as for the Bangladesh. Textile dyes are chemical substances which can cause serious damages to the nearby eco life. The treatment of the textile dyes after using in the factories is either costly or time consuming. As a result mills and factories are not willing to do the treatment process every time, rather they discharge it without any treatment. In this project textile dye degrading bacteria were isolated from the textile sludge to degrade the textile dyes since this biological process is less expensive than the other existing process. Two bacterial strain Brevibacillus laterosporus and Staphylococcus nepalensis were isolated from the textile sludge which was tested with two textile dyes; they are Yellow 4GL and Reactive Red 3BX. And these both bacteria are very much effective to degrade these dyes. Especially Brevibacillus laterosporus can de-color the Reactive Red 3BX dye in a very short time; even the higher concentration of the dye can be degraded.
Bacteriology of diabetic foot ulcers and their antibiotic resistance ability
(BRAC University, 12/15/2022) Baral, Poulomi; Afnan, Nafisa; Akter, Baby; Prapti, Shek Rabia; Haque, Dr. Fahim Kabir Monjurul
This study is aimed to isolate the pathogenic bacteria from diabetic foot ulcers and observe their antibiotic susceptibility against antimicrobial agents. Seventy-five patients diagnosed with diabetic foot ulcers were investigated. Pus samples collected from patients were cultured in the selective media to confirm the identity of the isolated pathogenic bacteria for each patient. Further, an antibiotic sensitivity test was performed by following the Kirby- Bauer Disc Diffusion Susceptibility Test Protocol. One hundred and forty-one pathogenic bacteria were identified from the ulcer patients. Proteus spp. and Klebsiella pneumoniae are the most common pathogenic bacteria isolated, respectively. Most of the Gram-negative bacteria were resistant to Beta-lactamase group’s Ampicillin. Such as Klebsiella pneumoniae (97.56%), Pseudomonas aeruginosa (95.24%), and Escherichia coli (81.82%). Proteus spp. was mostly sensitive to piperacillin-tazobactam (80%). On the other hand, Gram-positive Staphylococcus aureus showed mostly sensitivity towards both vancomycin and norfloxacin (79.17%).
Comparative analysis of plasmid presence and antibiotic resistance profiles in water samples with a focus on Dhaka City's water bodies (Dhanmondi & Gulshan Lake)
(BRAC University, 12/18/2025) Progga, Addrota Khan; Ahmed, Subhat Sumaila; Rahman, Tazkia; Naser, Iftekhar Bin
Antimicrobial resistance (AMR) is a growing global public health concern, with environmental reservoirs contributing significantly to the spread of antibiotic-resistant bacteria. Urban surface water bodies in densely populated cities are recognized as important hotspots due to continuous exposure to domestic, medical, and industrial waste. In Dhaka, Bangladesh, rapid urbanization and inadequate wastewater management have intensified this problem. This study comparatively analyzed the antibiotic resistance profiles and plasmid presence of Escherichia coli, Salmonella spp., and Vibrio cholerae isolated from water samples collected from Dhanmondi Lake and Gulshan Lake. Samples were processed using selective culture methods, followed by molecular confirmation through polymerase chain reaction (PCR). Antibiotic susceptibility testing was conducted using the Kirby–Bauer disk diffusion method, and plasmid DNA isolation was performed to assess the potential role of plasmids in resistance dissemination. Results indicated a high prevalence of antibiotic-resistant isolates in both lakes, with several strains exhibiting multidrug resistance. Differences in resistance patterns between the two sites suggest variation in environmental contamination pressures. A substantial proportion of isolates carried plasmids, highlighting the potential contribution of horizontal gene transfer to environmental AMR spread. These findings underscore the role of urban water bodies as reservoirs of antibiotic-resistant bacteria and resistance-associated plasmids, emphasizing the need for continuous monitoring and improved waste management strategies in rapidly urbanizing regions.
Correlation between plasmid presence & antibiotic resistance: in enteric bacteria; isolated from different water bodies inside Dhaka City
(BRAC University, 2/19/2026) Tabassum, Tasnim; Sarker, Aurchi; Asha, Kamrun Nahar; Naser, Iftekhar Bin
Antimicrobial resistance (AMR) is an endemic issue of public health in the world, and there is increasing evidence that surface water bodies are significant environmental reservoirs of antibiotic-resistant bacteria. This study has analyzed the relationship between the occurrence of plasmids and antibiotic resistance in the pathogenic enteric bacteria that develop in surface water sources in Dhaka Metropolitan City. To identify the contribution of anthropogenic interference to the waters of three urban water bodies, namely, Hatirjheel, Curzon Hall, and Ramna Lake, water samples were taken from January to June 2025, and with varying degrees of anthropogenic impact. Three clinically and ecologically important bacteria, i. e. Escherichia coli, Salmonella spp., and Vibrio cholerae, were the subject of the investigation. The selective and differential media (EMB, TCBS, and SS agar) were used to perform isolation, and antibiotic susceptibility testing was conducted to identify the profiles of resistance. Molecular validation was done by polymerase chain reaction (PCR) and plasmid isolation done to assess genetic basis of resistance. PCR amplicons and plasmid DNA were analyzed utilizing agarose gel electrophoresis, which allowed performing the correlation analysis between the plasmid carriage and the observed resistance patterns. The results showed that the prevalence of PCR-confirmed antibiotic-resisting isolates and plasmid-bearing isolates were very high in Hatirjheel and then in Ramna Lake, but relatively low in Curzon Hall. There was a close correlation existing between the presence of plasmids and the presence of multidrug resistance thereby highlighting the importance of plasmid-mediated horizontal gene transfer in water.
Detection of prevalence & characterization of thyroid disorder patients in Dhaka: a survey based study
(BRAC University, 2012) Allam, Md. Shafiul; Islam, Mohammad Rafiqul
Lactic acid fermentation of pasteurized and powdered milk and optimizing the factors affecting the fermentation process
(BRAC University, 2013-12) Sharar, Nowshin Shyara; Choudhury, Dr. Naiyyum
Yogurt is a basic dairy product that has been consumed for centuries as a part of the diet, even when its beneficial effects were neither fully known nor scientifically proven. With time, yogurt has been continuously modified to obtain a product with better appeal and nutritional effects. In this study, both spontaneous and inoculated fermentation of pasteurized and powdered milk was performed in order to study the quality of the yogurts. In addition to that, bacteria were isolated from both types of yogurts and their microscopic characteristics had been observed under the microscope. Several factors are required to produce a good quality yogurt; such as, temperature, pH, NaCl concentration, liquid and powdered milk concentration etc. These fundamental factors were optimized in such a way that the yogurt was produced in a short incubation period and the efficiency of the fermentation process was enhanced due to optimal conditions. Moreover, the quality and texture of the yogurt remained unchanged up to 5 days.
Analysis of factors influencing successful Agrobacterium-mediated genetic transformation in two Bangladeshi peanut (Arachis hypogaea L.) varieties BINA Chinabadam-2 and BINA Chinabadam-6 using embryonic leaflet explant
(BRAC University, 2014-03) Chowdhury, Iftekhar Mahmud; Islam, Dr. Aparna
Peanut (Arachis hypogaea L.) is an important crop both for its nutritional value and for its oil content in the seeds. But this economically important crop is susceptible to both biotic and abiotic factors that hamper its growth both in quality and quantity. Due to change in agricultural environment and also due to lack of resistance towards diseases the production is compromised. For this reason, genetic engineering is a possible tool to enhance the quality of the crop by introducing novel trait in it. To achieve that it a prerequisite to established a transformation protocol prior to any transformation event. Establishment of an efficient Agrobacterium-mediated transformation protocol requires optimization of several factors that affects the transfer of T-DNA. In the present study, these were optimized for two peanut varieties, namely, BINA Chinabadam 2, and BINA Chinabadam 6 using embryonic leaflet as a source of explant. In this study, Agrobacterium tumifaciens strain LBA4404 carrying pBI121 having GUS and nptII marker genes was used. T-DNA transfer was monitored through transient transformation assay utilizing GUS gene expression. Bacterial suspension having density (OD600) more than 1.0 with at least 1 hour of incubation period and minimum of 2 days of co-cultivation period found to be efficient for leaflet explants in both the varieties. Following transfer of T-DNA, presence of transgene within the infected tissue was observed by GUS histochemical transient assay.
Analysis of factors influencing successful Agrobacterium-mediated genetic transformation in two different explants of peanut (Arachis hypogaea L.) variety BINA Chinabadam-2
(BRAC University, 2014-03) Rafiq, Sreoshee; Islam, Dr. Aparna
Peanut (Arachis hypogaea L.) is a nutritious oil-seed crop. It has low productivity due to its susceptibility towards many biotic and abiotic factors. It has incompatibility towards conventional breeding techniques, thus imposing a barrier towards its germplasm improvement. Under the situation genetic engineering in peanut offers an alternative improvement technique in order to achieve improvement in its germplasm, thereby, enhancing its productivity. This study was carried out to analyze various transformation factors to determine their optimal condition so that a proper protocol can be established to carry out transformation in two explants, namely, decapitated half embryo and whole embryo of BINA Chinabadam-2. The explants were prepared and infected in Agrobacterium culture media. The explants were then allowed to co-cultivate in MS media containing 2mg/l BAP and 1mg/l kinetin. 25% of the explants were analyzed for transient expression by GUS histochemical assay and the rest were transferred to regeneration media containing 200mg/l cefotaxime. High transformation efficiency was received with minimum of 1 hour of infection duration, 24 hours of co-cultivation and optical density (600nm) of close to 1.0 in case of decapitated half embryo explants. One day old explants gave good response. For whole embryo with cotyledon attached, pre-culture of explants had negligible effect while an optical density of 1.0 gave best result which is in accordance to the results received for decapitated half embryo.
Determination of an efficient regeration protocol for Bangladeshi peanut varieties (Arachis hypogaea L.)
(BRAC University, 2014-10) Chowdhury, Shahana
Peanut is an economically important oilseed crop with high nutrition value. This plant is imposing several yield constrains like biotic and abiotic stresses. However, fungal diseases are mostly seen. Like other legumes, it has physiological barriers in traditional hybridization in such case “tissue culture regeneration ” offers a potential alternative for improving production in quantity and quality of this plant. Several attempts with various explants have already revealed in past few years but an efficient protocol with case by case study is yet to be revealed for popular Bangladeshi peanut varieties. In this study, the role and interaction of the most promising explant sources; effect of different growth hormones in different combination and concentration have been investigated for six farmer popular Bangladeshi cultivar to find out an efficient transformation amenable regeneration protocol of Arachis hypogaea . In this experiment, BAP singly gave indirect regeneration and BAP combined with kinetin gave direct regeneration from leaflet explant, 5 mg/l BAP with and without 0.5 mg/l Kn showed multiple shoots in lower length in case of BARI Chinabadam-7 and BARI Chinabadam-8. However, 2.00 mg/l BAP with and without 0.5 mg/l Kn showed multiple shoots in lower length in case of Dhaka Chinabadam- 1, BINA Chinabadam-2, BINA Chinabadam-4, BINA Chinabadam-6 varieties. The another promising explant half decapitate embryo, gave rapid multiple longer shoots in 3.00 mg/l BAP and 1.00 mg/l Kinetin combined media for most of the cases. Among all the varieties BINA Chinabadam-6 was resulted to be best among all the varieties. At the stage of rooting, three root induction hormone were tried - IBA, IAA, NAA and the concentration was about 0.1 and 0.2 mg/l; among them 0.2 mg/l IBA shows better root formation and highest survival rate at hardening stage. Seasonal impact on rooting was also studied where January to June is the suitable period where September to November, no rhizogenesis was occurred. BINA Chinabadam-4 and BINA Chinabadam-6 gave the higher number of pod formation then the other.
Study of IN VITRO regeneration and transformation parameters for the development of transgenic Tomato (Solanum Lycopersicum L.)
(BRAC University, 2014-10) Mukta, Fahima Akter
Investigation was carried out to develop an in vitro regeneration protocol using three locally grown farmer popular tomato varieties namely BARI Tomato 2, BARI Tomato 9 and Bahar. Later Agrobacterium mediated transformation study was performed to find out the best transformation parameters using these three varieties along with BARI tomato 7 variety. Tomato seeds were sterilized with 24 hours continuous shaking as it took less time for germination and cause less damage to embryo. During in vitro culture BARI tomato 2 and BARI tomato 9 variety showed better response in presence of 1 mg/l BAP (germination percentage 96%, 13 days for germination initiation and 24.8 shoots/explant and germination percentage 93%, 12.6 days for germination initiation and 19 shoots/explants respectively). Bahar variety respond well in 1 mg/l BAP + 0.1 mg/l IAA containing MS media combination (germination percentage 100%, 10 days for germination initiation and 39.6 shoots/explant). All three varieties showed cent percent rooting response in ½ MS + 0.2 mg/l IAA. However, there was no significant difference in rooting response in relation to shooting media. Seeds collected from well ripened fruits of in vitro regenerated plants showed 95-100% viability in germination test. Thus, indicates the reproducibility of the protocol. Transformation efficiency was found to be increased with the increase of optical density of Agrobacterium suspension. All the varieties gave 80-100% GUS positive expression in GUS assay at 0.62 OD600 and minimum 47% was found in BARI tomato 9 variety with 0.49 OD600. In the present study 20 minutes of incubation period with higher OD600 (0.62) gave better transformation in BARI tomato 2, BARI tomato 7 and BARI tomato 9 varieties. Interestingly, Bahar variety produced highest number of GUS positive explants (98%) in 30 minutes incubation period at similar OD. Among the co- cultivation periods 48 hours was found best for all four varieties in transient GUS assay. The highest regeneration percentage in presence of antibiotic (kanamycin, 150 mg/l) following transformation with pBI121 found to be 56% in Bahar variety. Again, when transformation was done by pH7WG2_OsNHX1_1.6 highest regeneration was achieved (23%) in Bahar variety when cultured in hygromycin, more than 4 mg/l.
In vitro culture establishment from Cotyledon and Embryonic Axis Explants of two Bangladeshi Sunflower (Helianthus annus L.) varieties
(BRAC University, 2015-03) Chowdhury, Maisha Mosharrat; Islam, Aparna
Sunflower is considered as source of cholesterol free edible oil. Because of cross pollinating nature of this plant, it is difficult to identify true breeding homozygous line, thus, breeding becomes intricate. Besides, due to biotic and abiotic stresses, development of this crop is urgent. This study was aimed to develop a potential alternative to improve qualitative and quantitative production of this crop through basic tissue culture regeneration. Several attempts with various explants have already discovered in past but no initiative was reported for Bangladeshi sunflower varieties. In present study, optimum seed sterilization method; the efficiency of different explants; effect of different growth hormones in different combinations and concentrations and rooting efficiency of initiated shoots were demonstrated for two farmer popular Bangladeshi sunflower varieties, namely BARI Surjomukhi 2 and BRAC Hysun 33. The seeds were washed with 70% ethanol for 3 minutes followed by vigorous hand shaking with 14% Clorox for 20 minutes. To collect explant, named embryonic axis, testas were removed and 3 mm piece from proximal portion of the seed was excised and inoculated in different combinations and concentrations of hormone supplemented media. For explant cotyledon, sterilized seeds were inoculated in germination media to obtain different ages seedlings, thus five, seven and nine days cotyledon explant was collected. In case of explant embryonic axis, BRAC Hysun 33 variety showed maximum (58.33%) regeneration in 1.0 mg/l BAP with 0.1 mg/l NAA hormone supplemented media while in BARI Surjomukhi 2 variety, 2.0 mg/l BAP gave highest (46.67%) regeneration. Elongated shoots were inoculated in 0.2 mg/l IBA containing media for root induction but further studies are needed to optimize rooting media concentration. The second explant, cotyledon remained nonregenerative in both varieties. Further studies need to be done to develop regeneration system from this explant. In future reproducibility of this protocol using embryonic axis needs to be evaluated.
IN VITRO culture establishment from hypocotyl and cotyledon explants of two Bangladeshi sunflower (Helianthus annuus L. ) varieties
(BRAC University, 2015-03) Oshin, Afsana Tasnim; Islam, Dr. Aparna
Sunflower (Helianthus annuus.L) is the world’s second most important oilseed crop. Plant tissue culture and gene transformation are the important tools for improvement of this crop. The purposes of this study are to optimize seed sterilization procedure, determine the most suitable and efficient explants along with their suitable age and size, and to optimize the hormonal concentration for shoot regeneration. Seeds being treated with 70% ethanol for 3 minutes and 14% Clorox for 20 minutes, with their testa being removed before being inoculated into the germination medium, were found to be optimum for the tissue culture technique. In this study, two varieties, BARI surjomukhi 2 and BRAC Hysun 33 were used as plant materials. Hypocotyls and cotyledons were excised from 5, 7 and 9 days and cultured on MS medium supplemented with eight different combinations of BAP and NAA hormones. The experiments were kept in 18/6 hour light/dark photoperiod at 26±2ºC. It was determined that MS medium supplemented with 1 mg/l BAP and 0.1 mg/l NAA is the best combination for 7 day old hypocotyl explants of both BARI surjomukhi-2 and BRAC Hysun 33 varieties. From 7 day old hypocotyl explants, the best shoot regeneration response of BARI surjomukhi-2 and BRAC Hysun 33 variety was 60% and 53.3%, with the best grown shoot that grew up to 2.08 cm and a of length 1.61 cm within 30 days of regeneration respectively. This clearly showed that MS medium supplemented with 1 mg/l BAP and 0.1 mg/l NAA is the best hormonal media combination for hypocotyl explants. Shoot regeneration efficiencies of the cotyledon explants on the same medium were lower in comparison with the hypocotyl explants. Cotyledon explants only grew large in size with time, but did not show any positive response like shoot regeneration. So, hypocotyls were proved to be better explants than cotyledons. In future, rooting at the base of the regenerated shoots will be tried to generate whole plantlet.
Isolation of Shiga toxin producing Escherichia coli 0157:H7 from street food and raw vegetables in Dhaka city
(BRAC University, 2015-04) Anjum, Afra; Islam, Namista
E. coli O157:H7, a Shiga toxin producing microbe was first acknowledged as a virulent organism in 1982 during an analysis of an outbreak of haemorrhagic colitis associated with consumption of hamburgers from a fast food chain restaurant. An inspection of more than three thousand E. coli cultures collected between 1973 and 1982 showed only one isolate with a serotype O157:H7. In the following ten years, there were just about thirty outbreaks documented in the United States. It is assumed that there might have been more cases, but remained unreported since an outbreak could not be detected as the number of affected was not large enough to lead it into an investigation. Ability of E. coli O157:H7 to induce injury in humans is a result of its ability to produce numerous virulence factors, most notably Shiga toxins Stx1 and Stx2, both of which constitute one of the most potent toxins known to man. Endothelial cells line the interior surface of blood vessels, and are known to be tremendously susceptible to E. coli O157:H7, which is cytotoxigenic to these cells. Besides, Shiga toxin, E. coli O157:H7 produces several other virulence factors, which include proteins which aid in the attachment and colonization of the bacteria in the intestinal wall and which can break down red blood cells and release iron to help support metabolism in E. coli . Virulence factors facilitate this organism’s ability to cause intestinal and extra-intestinal diseases such as diarrhoea, haemorrhagic colitis (HC), haemolytic uremic syndrome (HUS), urinary tract infections (UTI), septicaemia and neonatal meningitis. Street foods and raw vegetables are infamous for the lack of hygiene and potentially hazardous microbial quality. Ingestion of these foods may lead to diarrhoea. In this study r, 6 samples from Dhaka city was collected, cultured in various media for enumeration, isolation and screening of E. coli colonies which were further analysed to check for the presence of stx genes using PCR and gel electrophoresis. The six samples collected were: Salad, Fruit Mix, Sugar Cane Juice, Betel leaves, Pulse (from Bhelpuri) and raw coriander. The samples collected initially were enriched in enrichment media overnight, followed by a 6 fold dilution series which were then used for spread plating on nutrient agar and MacConkey agar. Pink colonies screened from MacConkey agar plates were streaked on EMB for confirmation with the observation of metallic sheen. The confirmed E. coli isolates were later subjected to DNA extraction and amplification after which the bands for stx genes were observed and recorded. Out of the six samples tested for stx1 and stx2 genes, four showed the presence of stx2 genes, which in many papers have been mentioned as the more virulent gene out of the two. The presence of the stx2 genes in regular food signifies how close we are to a large outbreak. Knowledge of processing such food or avoiding when possible may prevent occurrence of foodborne diseases.
Isolation of Kerosene degrading bacteria from soli samples and determination of optimum growth conditions
(BRAC University, 2015-04) Chowdhury, Mashiat Nawar
Oil spills are global catastrophes transpiring annually from minute to substantial amounts, threatening the lives of plants, animals and the health of human. Current physical and chemical management systems are very costly and less efficient. Bioremediation through utilization of oil-degrading bacteria proves to be our auspicious hope for the future. Kerosene is a mixture of hydrocarbons that is deployed in aviation fuels and contributes to extremely noxious pollution during spills. It is a conglomerate of benzene, toluene, ethylbenzene, xylene, along with high percentage of aromatic hydrocarbons that are carcinogenic. This makes kerosene imperative to be removed from the environment before its significant spread over large habitat. In this study, several bacterial isolates from four soil samples were assessed for their ability to degrade kerosene. They were grown on mineral salts broth for 7 days at 35°C in the absence of any carbon source apart from kerosene. Growth of the isolates were observed by visible turbidity and evaluated by CFU/mL on mineral salts agar. The isolates were identified as Nocardia, Corynebacterium, Bacillus, Pseudomonas and Arthrobacter through morphological characteristics and biochemical tests. The best potential isolate was tested for its optimum concentration of kerosene, optimum pH for growth and optimum concentration of ammonium sulfate (nitrogen source) requirement. Pseudomonas sp. exhibited to be the most promising amongst the isolated microbes at utilizing kerosene, followed by Bacillus sp., both of which were isolated from soils that were previously contaminated by oil. Isolates such as Nocardia and Corynebacterium taken from soil sample dearth of prior exposure to oil contamination were unable to grow in the presence of kerosene. Pseudomonas sp. tolerated kerosene at concentration as high as 6%, and showed optimum growth at 3% kerosene (v/v). Pseudomonas sp. was also found to grow best at near neutral pH and at nitrogen concentrations (ammonium sulfate) of 1 g/L.
Isolation and study of the optimum growth conditions of diesel degrading bacteria from soil
(BRAC University, 2015-04) Naila, Tasmin; Hossain, M. Mahboob
The rise in industrialization and globalization has made oil spills an environmental threat all over the world. Bioremediation can be considered as an effective aid to the clean-up process of spilled oil aside from expensive and invasive physical and chemical methods. The natural degradation of oil by microorganism can help remove residual oil pollutants. Hydrocarbon compounds present in petroleum products can have deteriorating effects on both wild life and humans. Diseases, disorders and even cancer of different organ systems have been linked to the exposure to these hydrocarbons. Microorganisms have metabolic capabilities to utilize the carbon compounds and degrade them to innocuous by-products. These abilities can be targeted for bioremediation purposes. The present study screened for bacteria with capabilities of utilizing diesel as sole source of carbon for growth. Eight isolates were derived from soils of four locations, among which three seemed to have prior exposure to diesel. The bacteria were individually cultured in a mineral salt broth devoid of carbon source except for diesel for 7 days at 35ºC. The growth of bacteria was observed from visible increase of turbidity and was enumerated by CFU/ml on mineral salt agar of same composition after 7 days of culture in the broth. The genera of the eight isolates were identified as Nocardia, Corynebacterium, Bacillus, Pseudomonas and Arthrobacter by morphological characterization and biochemical test results compared to standard references. Among the eight isolates, Pseudomonas sp. exhibited relatively higher ability to grow on diesel while Bacillus sp. and Arthrobacter sp. showed relatively less growth. Nocardia sp. and Corynebacterium sp. showed no tangible evidence of utilizing diesel as carbon source. This Pseudomonas sp. isolate was further used assess the effect of different concentration of diesel and pH values on growth. The result showed that optimal growth occurred at 3% (v/v) diesel concentration especially with agitation at 120 rpm and pH variation tests showed that near neutral pH values represent better growth conditions.
Studies on isolation of yeasts from natural sources for bioethanol production from vegetable peels and the role of cellulose degrading bacteria (Bacillus subtilis) on ethanol production
(BRAC University, 2015-08) Promon, Salman Khan; Hossain, M Mahboob
The requirement of an alternative clean energy source is increasing with the elevating energy demand of modern age. Microbial production of bioethanol can replace the conventional fossil fuel with green energy. In this study, local yeast isolates were used for the production of bioethanol using cellulosic vegetable wastes as substrate. This project were designed for the efficient bioconversion of lignocellulosic biomass into ethanol by microbial action. Wild-type yeast isolated form sugarcane juice (SC1) and date juice (DJ1) were used as ethanol producing organism. After proper isolation, identification and characterization of stress tolerance (thermo-, ethanol-, pH-, osmo- & sugar tolerance), detailed characterization and optimization of physiochemical parameters for ethanol production the strain is treating to be dubbed as an industrial strain. Very inexpensive and easily available raw materials (vegetable peel kitchen wastes) are used as fermentation media. The overall objective of this project is to meet the demand for an inexpensive and highly efficient integrated anaerobic Saccharomyces spp. fermentation process to produce ethanol as an energy source directly from insoluble lignocellulosic substrate (kitchen-waste). Fermentation was optimized with respect to temperature, reducing sugar concentration and pH. Analysis of fermentation characteristics under different substrate and environmental conditions, it was observed that temperature of 30°C and pH 6.0 were optimum for fermentation with maximum yield of ethanol. Influence of Bacillus subtilis increased the alcohol production rate from the fermentation of cellulosic materials. The cellulolytic activity of this cellulose degrading bacteria converts cellulose into smaller sugars which will be easier to be fermented by yeast. Maximum ethanol production by yeast was 17.39% using vegetable peels as substrate at 48 hours (30°C and substrate was treated with Bacillus subtilis) under shaking condition.
Extraction of secondary metabolites, phytochemical screening and the analysis of antibacterial activity in stevia rebaudiana
(BRAC University, 2015-09) Zohra, Fatima Tuz; Chowdhury, Ms. Jebunnesa
Stevia rebaudiana is a plant of the Asteraceae family and native to Paraguay. Its sweetness and calorie free property has increased its demand commercially all over the world as a sugar substitute in food beverages and medicines. Stevia has many pharmacological and therapeutic properties including antimicrobial, antifungal, antioxidant and anticarcinogenic activity. Due to this importance the leaf was analyzed for preliminary phytochemical studies to find the presence of phytoconstituents such as alkaloids, flavonoids, steroidal compounds, sponins, tannins, phenols, and cardiac glycosides. In this study, the crude plant extract from three different extractions (ethanol, methanol, and water) were collected and tested for the presence of phytochemicals. Comparative analysis of the antimicrobial activity of the extracts was investigated against four bacterial strains (Bacillus subtilis, Staphylococcus aureus, Streptococus peneumoniae and Shigella flexnari). This was done using agar diffusion method and as controls kanamycin, tetracycline and chloramphenicol were used. The diameter of the clear zone of inhibition surrounding the disc was measured in millimeters. The results showed that methanolic and ethanolic extracts of Stevia rebaudiana contained the highest amounts of phytochemicals. Antibacterial activity results showed there is no inhibitory effect of stevia against S.aureus and S.flexnari. The highest amount inhibition was formed against B.subtilis and S.pneumoniae. It can be concluded from the results that methanolic, ethanolic and aqueous extracts of Stevia rebaudiana may be considered as an antibacterial agent against S.pneumoniae and B.subtilis and be used to source antibiotic substances.
In silico structural analysis, physicochemical characterization and homology modeling of Arabidopsis thaliana Na+/H+ exchanger 1 protein
(BRAC University, 2015-09) Feisal, Mohammad Rafid; Islam, Dr. Aparna
Climate changes have detrimental effects on the plants such as an increased susceptibility towards pathogens or ill health leading to food insecurity. This is eminently observed in developing countries such as Bangladesh. Hence, it is of crucial importance to comprehend the mechanisms the plants use to adapt to environmental stresses, such as, salinity. NHX-type antiporter facilitates the exchange of Na+ for H+ across the membranes. It sequesters Na+ form the cytoplasm to vacuoles via the electrochemical H+ gradient generated by two H+- pumps. In Arabidopsis thaliana, NHX1 encodes the vacuolar sodium or proton antiporter and it is identified as a significant salt tolerance determinant that is able to catalyze Na+ accumulation in vacuoles. As such, it is necessary to determine the structure of the protein encoded by the NHX1 gene in Arabidopsis thaliana. This would allow us to establish the regions (e.g. active sites and secondary structural motifs) in the protein that affect the function and protein-protein interaction network in regard to the mechanisms involved in salinity tolerance. The objective of this study is to predict the three-dimensional structure of Arabidopsis thaliana sodium/hydrogen exchanger 1 protein via homology modeling and examine its physicochemical properties using in silico approaches. Biocomputational analyses of the target protein were performed using an array of online bioinformatics tools and databases and the homology model was developed using 3 different softwares (I-TASSER, Phyre2 and Easymodeller) and the best model was selected upon evaluation. In addition, the secondary structural motifs were identified within the model. The results suggested that the EasyModeller model, EM_Model 01, was the best amongst the three. It had the highest stereochemical quality scores and was considered to be the least unusual. The model consisted of α/β/γ topology where a single β-sheet constituted the β-hairpin as observed in the secondary structure schematic and topology diagrams. It was predicted that the presence of the β-hairpin allowed the protein to act as a membrane channel protein to facilitate the exchange of Na+ and H+.
Extraction of secondary metabolites, phytochemical screening and the analysis of antibacterial activity in Spirulina platensis
(BRAC University, 2015-10) Ferdaaus, Jannaatul; Chowdhury, Jebunnesa
Spirulina platenis is a multicellular and filamentous blue-green microalgae which is most well-known and broadly accessible. It develops in water, can be reaped and prepared effortlessly and has fundamentally high large scale and micronutrient substance. In numerous nations of Africa, it is utilized as human nourishment as a critical wellspring of protein and is gathered from normal water, dried and eaten. It has increased impressive prevalence in the human wellbeing nourishment industry and in numerous nations of Asia it is utilized as protein supplement and as human wellbeing sustenance. Spirulina has been utilized as a reciprocal dietary element of food for poultry and progressively as a protein and vitamin supplement to aquafeeds. Spirulina seems to have significant potential for improvement, particularly as a little scale crop for wholesome upgrade, employment advancement and ecological alleviation. In the current research work , the crude extracts of Spirulina platensis were collected using three solvents namely- Methanol , Ethanol and Distilled Water and phytochemical assay was performed on it to identify the secondary metabolites present in them. Antimicrobial activity was performed on the three types of crude extracts (which were initially diluted with Dimethyl Sulfoxide -DMSO) against Bacillus subtilis, Enterococcus faecalis , Staphylococcus aureus , Escherichia coli, using a positive (antibiotic disk) and negative control (0.25% DMSO), The antimicrobial tests were carried in agar diffusion technique using Mueller Hinton Agar (M-H) media. The results obtained from this study can act as a stepping stone in investigating the antimicrobial properties of Spirulina platensis extracts. This study could be the beginning of discovering a new microbial agent against certain bacterial species.