Characterization of <em>Alcaligenes faecalis</em> GPA-1 producing thermostable extracellular α-amylase

Abstract

The bacterium coded GPA-1(isolated by Dr V Thankamani in 1990) was characterized by standard methods including microscopy, special stains, biochemical tests and growth on various types of media for systematic identification up to genus level. With 16S rRNA gene sequencing, the isolate was identified as Alcaligenes faecalis and deposited in NCBI with GenBank Accession number HQ 848384. The isolate was screened for the production of enzymes like amylase, protease and carboxy methyl  cellulase (CMC). This isolate showed a clear zone of lysis on starch agar, yellow zone on CMC agar when stained with Congo red and a clear zone of casein hydrolysis in skim milk agar indicating amylase, cellulose and proteolytic activity respectively. Preliminary characterization of extra  cellular amylase was done. The strain was found to be alkalophilic as it grew well in pH 9.0 and 10.0. The optimum temperature and salinity were found to be 37oC and 3% respectively. Growth curve experiments of the organism in nutrient broth containing 1% starch at varying physical and nutritional parameters were done up to 72 hrs, and the samples were also  tested for pH changes, biomass, total protein, reducing sugars and  α-amylase activity. Soluble starch (1%) in standard nutrient broth and pH 8.0, 37oC, shaking at100 rpm and 40-44 hours incubation were found to be the optimum conditions for maximal enzyme production.