Proteases with characteristic stabilities are considered attractive candidates for industrial catalysis. In the present study, a potent bacterial strain KT004404, an inhabitant of hydrothermal vents, was isolated and characterized for protease production. Initial screening indicated that this strain produced a hydrolytic zone of 30 mm 16S rRNA-based identification revealed that our isolate was a strain of Bacillus subtilis. Optimum reaction condition for maximum protease production was determined as 55 °C, pH 6, 1 % inoculum size and malt extract as primary growth substrate supplemented with 1 % dextrose. Yield of the enzyme was increased up to 7.53 folds with a specific activity of 55.125 U/mg after gel filtration chromatography. SDS-PAGE analysis confirmed the size of protease as 28.24 kDa. Purified enzyme retained its catalytic activity over a broad range of temperature (5 to 65 °C) and pH [5-8]. Addition of metal ions shown to have a stimulatory effect on catalytic properties while EDTA inhibited the efficiency of the enzyme confirming it as a metalloprotease. Protease exhibited excellent stability and activity in the presence of anionic surfactants, solvents, and detergents. The results of dehairing and destaining experiments suggested that the protease produced by B. subtilis KT004404 could be used in leather and textile industries with ecological benefits.
The distinctive chemical, physical, thermal and mechanical properties of graphene made it widely recognized material in wide-ranging field of science and technology. Generally, the synthesis of graphene or reduced graphene oxide (rGO) requires two main steps. The first step involves the oxidation of graphite to graphene oxide (GO) and in the second step, reducing agents or reductants contribute to the reduction of GO to form rGO. A large number of reducing agents have been applied to synthesize rGO such as hydrazine, hydroxyl amine, sodium borohydride, etc. However, the hazardous nature of such reducers created a space for the research on green reducing agents for rGO synthesis. This study introduces the low-cost green synthesis of rGO via green reducing agents such as eucalyptus hybrid extract, thiourea, lemon extract and starch. Among all the green reductants, eucalyptus hybrid extract exhibited the remarkable reduction of GO, as confirmed by VU-visible spectroscopy, Fourier transform infrared spectroscopy, and X-ray diffraction results. The absorption peak of rGO-eucalyptus is appeared at 272 nm, whereas the d-spacing between layers is determined to be 0.364 nm. The obtained band gap of rGO-eucalyptus (2 eV) is found less as compared with other reducing agents such as thiourea, lemon extract and starch. The stretching vibration of oxygen functionalities appeared in FTIR of GO, is disappeared after reduction with eucalyptus extract. The flavonoid components of eucalyptus extracts are antioxidant in nature and hence, work as reducing agents.
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