Aims: The aims were to isolate a raw starch-degrading a-amylase gene baqA from Bacillus aquimaris MKSC 6.2, and to characterize the gene product through in silico study and its expression in Escherichia coli.
Methods and Results:A 1539 complete open reading frame of a starchdegrading a-amylase gene baqA from B. aquimaris MKSC 6Á2 has been determined by employing PCR and inverse PCR techniques. Bioinformatics analysis revealed that B. aquimaris MKSC 6.2 a-amylase (BaqA) has no starchbinding domain, and together with a few putative a-amylases from bacilli may establish a novel GH13 subfamily most closely related to GH13_1. Two consecutive tryptophans (Trp201 and Trp202, BaqA numbering) were identified as a sequence fingerprint of this novel GH13 subfamily. Escherichia coli cells produced the recombinant BaqA protein as inclusion bodies. The refolded recombinant BaqA protein degraded raw cassava and corn starches, but exhibited no activity with soluble starch. Conclusions: A novel raw starch-degrading B. aquimaris MKSC 6.2 a-amylase BaqA is proposed to be a member of new GH13 subfamily. Significance and Impact of the Study: This study has contributed to the overall knowledge and understanding of amylolytic enzymes that are able to bind and digest raw starch directly.
Partially purified α‐amylase from Bacillus aquimaris MKSC 6.2, a bacterium isolated from a soft coral Sinularia sp., Merak Kecil Island, West Java, Indonesia, showed an ability to degrade raw corn, rice, sago, cassava, and potato starches with adsorption percentage in the range of 65–93%. Corn has the highest degree of hydrolysis followed by cassaca, sago potato and rice, consecutively. The end products of starch hydrolysis were a mixture of maltose, maltotriose, maltotetraose, maltopentaose, maltohexaose, and small amount of glucose.
Inulin degrading bacteria is a potential source of inulin degrading enzymes, an enzyme which convert inulin into fructose and fructooligo-saccharides (FOS) prebiotic. The purpose of the study was to find inulin degrading bacteria. The methods that used to find inulin degrading bacteria were indirect and direct isolation method using inulin as the sole carbon source. Bacteria was characterized colony morphology. Inulin degrading bacteria were screened from two rizosphere dahlia tuber in West Sumatera (Solok and Padang Panjang). In the research has been found five inulin degrading bacteria isolates. Isolate bacteria RZ-01, RZ-02 from rizosphere dahlia tuber in Padang Panjang, isolate bacteria A1-KG, A2-KG and UKG from rizosphere dahlia tuber in Solok. All isolates grow at room temperature and 40ºC. All isolates were classified as mesophilic bacteria. Shape and colour of RZ-01, A2-KG and UKG colonies were circular and white respectively. RZ-02, A1-KG colonies were circular and yellowish.
Glucoamylase from the yeast Saccharomycopsis fibuligera R64 (GLL1) has successfully been purified and characterized. The molecular mass of the enzyme was 56,583 Da as determined by mass spectrometry. The purified enzyme demonstrated optimum activity in the pH range of 5.6-6.4 and at 50• C. The activity of the enzyme was inhibited by acarbose with the IC50 value of 5 µM. GLL1 shares high amino acid sequence identity with GLU1 and GLA1, which are Saccharomycopsis fibuligera glucoamylases from the strains HUT7212 and KZ, respectively. The properties of GLL1, however, resemble that of GLU1. The elucidation of the primary structure of GLL1 contributes to the explanation of this finding.
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