Md. Nur Hossain

Nucleic acid amplification: Alternative methods of polymerase chain reaction.

Nucleic acid amplification is a valuable molecular tool not only in basic research but also in application oriented fields, such as clinical medicine development, infectious diseases diagnosis, gene cloning and industrial quality control. A comperehensive review of the literature on the principles, applications, challenges and prospects of different alternative methods of polymerase chain reaction (PCR) was performed. PCR was the first nucleic acid amplification method. With the advancement of research, a no of alternative nucleic acid amplification methods has been developed such as loop mediated isothermal amplification, nucleic acid sequence based amplification, strand displacement amplification, multiple displacement amplification. Most of the alternative methods are isothermal obviating the need for thermal cyclers. Though principles of most of the alternate methods are relatively complex than that of PCR, they offer better applicability and sensitivity in cases where PCR has limitations. Most of the alternate methods still have to prove themselves through extensive validation studies and are not available in commercial form; they pose the potentiality to be used as replacements of PCR. Continuous research is going on in different parts of the world to make these methods viable technically and economically.

Critical Factors Affecting the Success of Cloning, Expression, and Mass Production of Enzymes by Recombinant E. coli

E. coli is the most frequently used host for production of enzymes and other proteins by recombinant DNA technology. E. coli is preferable for its relative simplicity, inexpensive and fast high-density cultivation, well-known genetics, and large number of compatible molecular tools available. Despite all these advantages, expression and production of recombinant enzymes are not always successful and often result in insoluble and nonfunctional proteins. There are many factors that affect the success of cloning, expression, and mass production of enzymes by recombinant E. coli. In this paper, these critical factors and approaches to overcome these obstacles are summarized focusing controlled expression of target protein/enzyme in an unmodified form at industrial level.

Screening of Lactobacillus spp. from Buffalo Yoghurt for Probiotic and Antibacterial Activity

Since the beneficial effects of viable probiotic bacteria as dietary supplements have gained huge research interest, Lactobacillus spp. with probiotic characteristics are widely used to prepare fermented dairy products such as yoghurts, milk-shakes etc. In this study, eight (08) homemade yoghurt samples were collected from different regions in the country for isolation of probiotic Lactobacillus spp. Among the samples, four (04) isolates were identified as Lactobacillus plantarum based on their growth and biochemical characteristics. The Isolates were resistant to NaCl (1-9%) and bilesalt (0.05-0.3%) and showed good growth in the acidic condition, while maximum growth was observed at pH around 6.0. The isolates were examined for their antibacterial activity against nine (09) different test pathogens and found all pathogens are inhibited their growth to some extent but maximum zone of inhibition was observed against Bacillus cereus (53.20 mm) and minimum was against Staphylococcus aureus (19 mm) after 72 hour incubation. The results of the present study indicate that, homemade yoghurts in Bangladesh are potential source of probiotic Lactobacillus spp. Further extensive research on isolation and characterization of probiotic organisms from local fermented foods and their growth optimization might be required for development of probiotic enriched food supplements in our country.

Quality comparison and acceptability of yoghurt with different fruit juices.

Yoghurt is consumed worldwide for its nutritional and health benefits. The research was conducted to prepare fruit yoghurt with different level of fruit juice (5%, 10% and 15%) of different fruits (strawberry, orange and grape). Different physico-chemical and microbiological characteristics were analyzed to assay the quality of the yoghurts. Yoghurts fortified with 10% orange juice was the best in quality among the others. The smell and taste, body and consistency and color and texture of the fruit yoghurts were equally acceptable. 10% and 15% strawberry fruit yoghurt contain more acid and its texture was cracked down in refrigeration temperature. The moisture and acidity content of fruit yoghurts were increased than plain yoghurt because of high content of these in the fruits. The fat, protein, carbohydrates and ash content of strawberry and orange fruit yoghurt were decreased than normal plain yoghurt. But the carbohydrates content of grape yoghurt were increased because grape contains more sugar than milk and other two fruits. Statistical analysis showed that yoghurt with 10% orange juice was more acceptable than others comparing all quality characteristics. The microbiological quality of the fruit yoghurts was also acceptable because of acid content of the fruits. In case of strawberry yoghurt, fruit juice concentration more than 5% was not suitable for fruit yoghurt because that are highly acidic and curd was cracked down at refrigerated condition. This formulation and quality findings will be helpful to set up fruit yoghurt industry.

Antimicrobial and antioxidant activities of Saccharomyces cerevisiae IFST062013, a potential probiotic

BackgroundProbiotic yeast has become a field of interest to scientists in recent years.MethodsConventional cultural method was employed to isolate and identify yeast and standard methods were used to determine different probiotic attributes, antimicrobial and antioxidant properties.ResultsThis study reports potential probiotic properties of a strain of S. cerevisiae IFST 062013 isolated from fruit. The isolate is tolerant to a wide range of temperature and pH, high concentration of bile salt and NaCl, gastric juice, intestinal environment, α-amylase, trypsin and lysozyme. It can produce organic acid and showed resistance against tetracycline, ampicillin, gentamycin, penicillin, polymixin B and nalidixic acid. It can assimilate cholesterol, can produce killer toxin, vitamin B12, glutathione, siderophore and strong biofilm. It showed moderate auto-aggregation ability and cell surface hydrophobicity. The isolate can produce enzymes such as amylase, protease, lipase, cellulose, but unable to produce galactosidase. The isolate can’t produce gelatinase and DNase. The isolate showed moderate anti-microbial activity against bacteria and fungi and cell lysate showed better antimicrobial activity than whole cell and culture supernatant. Again, the isolate showed better anti-bacterial activity against gram negative bacteria than gram positive. The isolate showed strong antioxidant activity, reducing power, nitric oxide and hydroxyl radical scavenging activity, significant brine shrimp cytotoxicity and acute toxicity and metal ion chelating activity. The isolate did not induce any detectable change in general health of mice upon oral toxicity testing and found to be safe in mouse model. The isolate improve lymphocyte proliferation and cytokine production in treated mice.ConclusionsSuch isolate could be potential as probiotic to be used therapeutically.

Formulation and nutritional evaluation of a healthy vegetable soup powder supplemented with soy flour, mushroom, and moringa leaf

Abstract The research study was conducted to develop a healthy vegetables soup powder supplemented with soy flour, mushroom, moringa leaf and compare its nutritional facts with locally available soup powders. Proximate analysis and sensory evaluation were done by standard method. In this study, moisture, ash, protein, fat, fiber, carbohydrate, and energy content were ranged from 2.83% to 5.46%, 9.39% to 16.48%, 6.92% to 16.05%, 4.22% to 6.39%, 0.22% to 1.61%, 58.81% to 75.41%, and 337.42 to 386.72 kcal/100 g, respectively. Highest content of vitamin D, minerals, protein, and fiber and lowest content of moisture, fat, and carbohydrate were found in the presently developed soy–mushroom–moringa soup powder compare to locally available soup powders. Vitamin C was also found significantly higher than locally available soup powders S1, S2, and S3. Heavy metals were not found in any of the soup powders. On the sensory and microbiological point of view, the presently developed soup powder was found highly acceptable up to 6 months. So, the developed soy–mushroom–moringa soup powder is nutritionally superior to locally available soup powders and sufficient to meet day‐to‐day nutritional requirements as a supplement.