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The aim of this study was to characterize the organic solvent and detergent tolerant properties of recombinant lipase isolated from thermotolerant Bacillus sp. RN2 (Lip-SBRN2). The isolation of the lipase-coding gene was achieved by the use of inverse and direct PCR. The complete DNA sequencing of the gene revealed that the lip-SBRN2 gene contains 576 nucleotides which corresponded to 192 deduced amino acids. The purified enzyme was homogeneous with the estimated molecular mass of 19 kDa as determined by SDS-PAGE and gel filtration. The Lip-SBRN2 was stable in a pH range of 9–11 and temperature range of 45–60 °C. The enzyme was a non metallo-monomeric protein and was active against pNP-caprylate (C8) and pNP-laurate (C12) and coconut oil. The Lip-SBRN2 exhibited a high level of activity in the presence of 108% benzene, 102.4% diethylether and 112% SDS. It is anticipated that the organic solvent and detergent tolerant enzyme secreted by Bacillus sp. RN2 will be applicable as catalysts for reaction in the presence of organic solvents and detergents.

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A superoxide dismutase gene from thermotolerant Bacillus sp. MHS47 (MnSOD47) was cloned, sequenced, and expressed. The gene has an open reading frame of 612 bp, corresponding to 203 deduced amino acids, with high homology to the amino acid sequences of B. thuringiensis (accession no. EEN01322), B. anthracis (accession no. NP_846724), B. cereus (accession no. ZP_04187911), B. weihenstephanensis (accession no. YP_001646918), and B. pseudomycoides. The conserved manganese-binding sites (H28, H83, D165, and H169) show that MnSOD47 has the specific characteristics of the manganese superoxide dismutase (MnSOD) enzymes. MnSOD47 expressed an enzyme with a molecular weight of approximately 22.65 kDa and a specific activity of 3537.75 U/mg. The enzyme is active in the pH range 7–8.5, with an optimum pH of 7.5, and at temperatures in the range 30–45 °C, with an optimum temperature of 37 °C. Tests of inhibitors and metal ions indicated that the enzyme activity is inhibited by sodium azide, but not by hydrogen peroxide or potassium cyanide. These data should benefit future studies of MnSODs in other microorganisms and the biotechnological production of MnSOD47, and could also be used to develop a biosensor for the detection of antioxidants and free radical activity. In the future, this basic knowledge could be applicable to the detection of cancer risks in humans and therapeutic treatments.

ABSTRACT:Gene encoding for endo-1,4-β-mannanase (EC 3.2.1.78) from Bacillus licheniformis THCM 3.1 was cloned and over-expressed in pET 100/D TOPO vector. The molecular weight of the purified enzyme was about 40 kDa. This enzyme had an optimum pH of 9 and an optimum temperature of 45°C and retained up to 77% of its activity after incubation for 48 h. The activity of the enzyme was inhibited by 10 mM of Pb 2+ , Ag + , Fe 3+ , Sn 2+ , Cu 2+ , and EDTA. Although partially inhibited, the enzyme retained much of its activity when the reaction solution was mixed with 15% (v/v) of the organic solvents acetone, toluene, benzene, dimethyl sulphoxide, 2-propanol, acetonitrile, or cyclohexane.

The Cu/Zn superoxide dismutase gene from Wuchereria bancrofti (Cu/Zn WbSOD) was isolated by PCR using degeneracy primers. The complete Cu/Zn WbSOD consisted of 1,032 nucleotides containing 4 exons (477 nucleotides) and 3 introns. The molecular phylogenetic analysis of the Cu/Zn WbSOD gene in comparison with those from other organisms revealed that the gene was classified in the same clade to those of filarial Brugia malayi and Brugia pahangi (bootstrap value at 90). The nucleotide and deduced amino acid sequences of Cu/Zn WbSOD exhibited the similarity to those of intracellular Cu/Zn SOD of B. malayi and B. pahangi. The amino acid comparison of Cu/Zn WbSOD to others revealed that the binding sites and active sites were conserved. The expression of this gene yielded 16.366 kDa in size. After Ni-IDA column purification, the enzyme showed specific activity of 8.5 U/mg and 42.1% yield. The enzyme activity was inhibited when 6 mM KCN was added.

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