Bacillus thuringiensis (Bt) biopesticides, a recognized eco-friendly pest control agent, can be used to reduce many problems associated with indiscriminate use of chemical pesticides such as environmental pollutions, public health problems, emergence of resistance among pests in many developing countries etc. Bt strains were, therefore, isolated from different ecosystems of Bangladesh and characterized based on biochemical typing, 16S rRNA gene analysis, plasmid and cry genes profiles. Bt index was calculated 0.86 in this study and variations in abundance and distribution pattern of 16 different biotypes were demonstrated within 316 indigenous Bt strains which was compared to the other parts of the world. Bt indiana (17.8%), Bt kurstaki (16.7%) and Bt thuringiensis (12.7%) were found to be the most prevalent in Bangladesh among other biotypes. Hemolytic activity was variable among the biotypes and it was maximum for Bt biotype 10 (100%). Plasmids in the biotypes indiana, kurstaki, thuringiensis and israelensis were observed to occupy a wider range than other biotypes. The screening for insecticidal genes viz. cry1, cry2, cry3, cry4A, cry8, cry9, cry10 and cry11 in the native Bt strains revealed their presence in varied proportion rendering cry1, cry2 and cry3 the most abundant. The abundance of Bt strains, their diversities and the cry genes profile were thus analyzed in this study which will be the basis for further research development with Bt biopesticide in Bangladesh.

Pasteurization of Milk through Direct Heating up to 75°C over Kitchen Stove at Home

The present study was aimed to develop an enzyme assisted dehairing method as an alternative and ecofriendly technique to reduce the use of harsh chemicals in leather manufacturing. For this purpose, two proteases namely alkaline protease (601 U/ml) and keratinase (132 U/ml) were produced by Bacillus licheniformis MZK05M9 (BlM9) in Soya molasses medium and Feather mill medium respectively, in 7.0 L bioreactor at pH 7.5 and 37°C. The cell free enzyme preparations were used together at 2.5% level in dehairing experiments. Three sets of experiments for dehairing of goat skins were performed with (1) enzymes; (2) enzymes and 5% lime (CaO) and (3) 2% sodium sulfide (Na2S) and 5% lime. The treatment with enzymes removed 85% of hair from goat skin after 24 hrs under mild shaking condition at room temperature where as the treatment with enzymes and 5% lime together resulted in 100% dehairing under similar conditions. Sodium sulfide along with lime also removed 100% hair faster (with 20 hrs) than other two treatments. The grain surface of the enzyme treated skin was smoother and silkier than that of the chemicals treatment as revealed by Scanning Electron Microscopy. Thus these results indicated that, the enzyme assisted method can be applied in largescale dehairing trial to reduce the use of harsh sodium sulfide.Bangladesh J Microbiol, Volume 32, Number 1-2,June-Dec 2015, pp 33-37

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.

Pasteurization of Milk through Direct Heating up to 75°C over Kitchen Stove at Home