The street foods play an important socioeconomic role in meeting food and nutritional requirements of city consumers at affordable prices to the lower and middle income people. The number of food poisoning notifications rose steadily worldwide since the inception ofE. coliO157:H7 outbreak in the 1980s to date. This may be partly attributed to improved surveillance, increased global trade and travel, changes in modern food production, the impact of modern lifestyles, changes in food consumption, and the emergence of new pathogens. Consumer’s knowledge and attitude may influence food safety behavior and practice. For the sake of public health, it is important to understand the epidemiology of foodborne illnesses that help in prevention and control efforts, appropriately allocating resources to control foodborne illness, monitoring and evaluation of food safety measures, development of new food safety standards, and assessment of the cost-effectiveness of interventions. This review paper described the sociodemographic characteristics, common hazards, and occupational hazards of street food vendors, microbial risk associated with street food, food safety interventions and control measures, regulatory aspects and legal requirements, financial constraints, and attitudes.

This study demonstrated that glucose-induced proton release from yeast cells was more sensitive to various inhibitors than cell proliferation. In this study the inhibition of glucose-induced proton release was determined on the basis of color change of pH indicator, methyl red, from pH 5 to pH6 at cell density of 2.5 × 10⁷ cells/ml. When yeast cells were incubated with the inhibitors of glucose intake, glycolysis, and plasma membrane H ⁺ -ATPase for 1 h, these cytotoxic effects were observed by following the change in absorbance at 527 nm due to methyl red for 5 min. The cytotoxic effects of heavy metal ions, detergents and quinones were observed in the same manner. The above method was superior in sensitivity and measurement time to cell proliferation measurement that required 9 h. This visual cytotoxicity test (methyl red test) is expected to be useful as simple and rapid cytotoxicity test with yeast cells.

An alkaline protease from Bacillus licheniformis MZK05M9 (BlM9), a mutant strain developed in our laboratory, has been partially purified and characterized for its robustness and eco-friendly application potential in processing of hides and skins for leather manufacturing and detergent industries. The enzyme was purified 2.70 fold with specific activity of 1624U/mg in comparison to crude enzyme extract by using ammonium sulfate precipitation, dialysis and Sephadex G-75 column chromatography. The molecular mass of the enzyme was 27.2 kDa as judged by SDS–PAGE. The purified protease had a pH optimum of 8.5 and temperature optimum of 55°C. According to the inhibition profiles obtained with the various protease inhibitors, it was confirmed that the partially purified protease belongs to the serine protease type. The activity of partially purified enzyme was enhanced by calcium, magnesium, barium, potassium and manganese ions and strongly inhibited by mercury ion. In addition, the protease showed remarkable stability in the presence of 1% SDS; 1, 3 and 5% Triton X-100 and H₂O₂, which comprise the common bleach-based detergent formulation. The enzyme was found equally efficient to a commercial enzyme Oropon K (one of the commercial enzymes imported into Bangladesh for bating purpose) in bating of animal hide as proved by different comparative qualitative tests such as tensile strength, percent of elongation, stitch tears strength, water vapor permeability, grain crack strength and tongue tear strength tests. In addition, the stability profile (pH, temperature and surfactants) and blood stain removal data also revealed its suitability for application in detergent industry. An alkaline protease from Bacillus licheniformis MZK05M9 (BlM9), a mutant strain developed in our laboratory, has been partially purified and characterized for its robustness and eco-friendly application potential in processing of hides and skins for leather manufacturing and detergent industries. The enzyme was purified 2.70 fold with specific activity of 1624U/mg in comparison to crude enzyme extract by using ammonium sulfate precipitation, dialysis and Sephadex G-75 column chromatography. The molecular mass of the enzyme was 27.2 kDa as judged by SDS–PAGE. The purified protease had a pH optimum of 8.5 and temperature optimum of 55°C. According to the inhibition profiles obtained with the various protease inhibitors, it was confirmed that the partially purified protease belongs to the serine protease type. The activity of partially purified enzyme was enhanced by calcium, magnesium, barium, potassium and manganese ions and strongly inhibited by mercury ion. In addition, the protease showed remarkable stability in the presence of 1% SDS; 1, 3 and 5% Triton X-100 and H₂O₂, which comprise the common bleach-based detergent formulation. The enzyme was found equally efficient to a commercial enzyme Oropon K (one of the commercial enzymes imported into Bangladesh for bating purpose) in bating of animal hide as proved by different comparative qualitative tests such as tensile strength, percent of elongation, stitch tears strength, water vapor permeability, grain crack strength and tongue tear strength tests. In addition, the stability profile (pH, temperature and surfactants) and blood stain removal data also revealed its suitability for application in detergent industry.

Bacillus licheniformis MZK05 was subjected to mutation by ultraviolet radiation for enhanced production of keratinase. Of 750 isolates from irradiated plates, 200 colonies that showed zone of casein hydrolysis on Skim Milk Agar were cultured in liquid Feather Meal Medium containing digested feather as carbon and nitrogen source in shake culture at 37ºC. The mutant B. licheniformis MZK05M9 (BlM9) exhibited highest enzyme activity of 170 ± 5.63 U/ml as compared to 74 ± 5.29 U/ml by the wild MZK05. Both the strains were examined for the presence of gene encoded for keratinase (kerA gene) by PCR using primer which showed the product sizes 1156 bp and 520 bp, respectively for MZK05 and BlM9. The keratinase from both strains exhibited a thermal stability of about 97% for 2 hrs at 40°C whereas the keratinase of the mutant strain showed less stability (55%) at 50°C. The BlM9 while cultivated in batch culture in 7 litre bioreactor for production of the keratinase in the Feather Meal Medium, the productivity was found to be double (17,608 U/L/hr) than that of in the shake flask culture (8,525 U/L/hr). This improved strain thus will be very useful for large scale production of keratinase enabling its technical applications in industry. Dhaka Univ. J. Biol. Sci. 24(1): 17-23, 2015 (January)

Thrombosis leads to myocardial infarction, stroke and other cardiovascular complications. Microbial thrombolytic agents such as urokinase, streptokinase etc. are used to treat complications related to thrombosis. To search for new microbial enzymes as thrombolytics having better efficacy and specificity, Bacillus licheniformis EMS-O-1 mutant strain was cultured in modified urea-molasses media followed by purification using ammonium sulphate precipitation and ultrafiltration through centricon tube of 100 MWCO value. The yield of crude enzyme was 11129.14 U/mg and after purification 40180.46 U/mg. Purification process increased the specific activity of purified enzyme to 12.28 fold with a recovery of 17.79%. The purified enzyme was a serine protease with molecular weight of 25.5 kDa as confirmed by irreversible inhibition of activity with phenylmethylsulfonyl fluoride (PMSF) followed by SDS-PAGE gel image and by LC-MS analyses. In vitro clot lysis assay of the purified enzyme exhibited 38.30% thrombolytic activity. The crude enzymes from the mutant strain EMS-O-1 were found to be stable up to 50oC and showed maximum stability between pH range 7.5 to 8.5. These findings signify that proteases produced by B. licheniformis mutant have the potential to be developed as a viable thrombolytic agent.Dhaka Univ. J. Pharm. Sci. 15(2): 135-141, 2016 (December)