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Background: Due to the importance of microbial proteases in biotechnological applications, a number of microorganisms are being explored. The production, purification and characterisation of extracellular metallo-proteases by producing Bacillus sp. KG5 was studied. Material and Methods: Bacterial strain KG5 was isolated from Kös (Bingöl) hot spring. The strain KG5 was identified by morphological, physiological, biochemical and 16S rRNA gene sequencing. The effects of various parameters on protease production, such as time, temperature, pH, carbon and nitrogen sources and CaCl2 were studied. The enzyme was purified by ammonium sulphate precipitation and Sephadex G-75 gel permeation chromatography. Molecular weight was calculated by sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE) and zymographic analysis. The effects of some metal ions, chelators and inhibitors on enzyme activity were determined. Results: The optimum temperature, pH and incubation period for protease production were 40-45°C, 7.0 and 24 h, respectively. It was determined that the best nitrogen sources were yeast extract and urea, while the best carbon sources were lactose and galactose. However, glucose as a source of carbon was found to inhibit the production of the enzyme. The maximum enzyme production was increased in the presence of CaCl2. The molecular weight of purified enzyme was found to be approximately 48 kDa. It was found that the enzyme was fully stable in the presence of 2 mM CaCl2 at 50°C after 120 min. Purified protease was significantly activated by Ca 2+ and Mg 2+ , while it was greatly inhibited by Cu 2+ , Zn 2+ , Hg 2+ and SDS as well as by the metal ion chelators ethylenediaminetetraacetic (EDTA) and 1,10-phenanthroline. Phenylmethylsulfonyl fluoride (PMSF) had a little effect on the enzyme. Conclusions: Our findings suggest the potential of this isolate for protease production and that this enzyme may be suitable for biotechnological applications.

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The polyphenol oxidase (PPD) is an enzyme that is responsible for the enzymatic browning of fruits and vegetables. This is generally undesired process and need to be prevented in food technology. PPD from purslane was purified, characterised and the kinetic parameters for three substrates namely, catechol, L-Dopa and 4-methylcatechol were determined. The optimum pH and temperature values were found to be pH 7.0 and 50 °C, respectively using the catechol as substrate. The apparent molecular weight of the PPD from purslane was determined as high as 163 kDa by partially denaturing SDS-PAGE. Moreover, the inhibition kinetics of the purified PPD were determined, using both synthetic and natural inhibitors. Among inhibitors tested, ascorbic acid was the most effective inhibitor with the lowest Ki value of 0.36 mM. This is the first study on the purification and characterisation of PPD from purslane (Portulaca oleracea) that may provide new insight into how to overcome the enzymatic browning.Keywords: Portulaca oleracea; polyphenol oxidase; purification; kinetics; inhibitors.Practical Applications: Understanding inhibition mechanism of PPD may provide insight into plant browning in food industry.

In this study, the potential biosorption characteristics of the thermophilic Anoxybacillus flavithermus (A. flavithermus) was investigated for the removal of the chlorophenoxy acid derivates, namely, 2,4‐dichlorophenoxy acetic acid (2,4‐D), 2,4‐dichlorophenoxy propanoic acid (2,4‐DP or dichlorprop), and 2,4‐dichlorophenoxy butyric acid (2,4‐DB). The experiments were performed for the simultaneous biosorption of the studied pesticides. Optimum biosorption conditions were determined as a function of contact time, pH of the solution, amount of biomass, and initial pesticides concentrations. The concentrations of the pesticides in the remaining solutions were simultaneously analyzed by high performance thin layer chromatography. The optimum parameters were found as pH: 4.0 for biosorption medium, 60 min of contact time, 50 mg of bacteria, and 50 mg L−1 of initial pesticides concentrations. Langmuir and Freundlich models were applied to describe the biosorption isotherm of the pesticides by A. flavithermus as biomass. Biosorption of pesticides on to A. flavithermus showed pseudo first‐order rate kinetics at different initial concentration of pesticides and different temperatures. The experimental adsorption data were fitted both the Langmuir and Freundlich adsorption models. Fourier‐transform Infrared spectroscopy was used to understand the bonding mechanism of pesticides to biosorbent and surface functionality of the biosorbent The highest pesticide uptake was calculated from Langmuir isotherm and found to be 24.15 mg g−1 for 2,4‐D. Among the studied pesticides, 2,4‐DP showed difference adsorption behavior. According to in your comments the reason of this that 2,4‐DP contain an asymmetric carbon atom, which provide a molecular chirality. © 2011 American Institute of Chemical Engineers Environ Prog, 2011