Carbohydrate-Active Enzymes of a Novel Halotolerant Alkalihalobacillus Species for Hydrolysis of Starch and Other Algal Polysaccharides

Halotolerant bacteria capable of starch hydrolysis by their amylases will benefit various industries, specifically since the hydrolytic activity of current industrial amylases is inhibited or even absent in salt-rich or alkaline environments. Seeking novel enzymes, we analyzed the entire genome content of a marine bacterium isolated from the gut of sea urchins to compare it against other bacterial genomes. Conditions underlying a-amylase activity were examined in vitro at various salinities (0 to 4%) and temperatures (25°C to 37°C). Genomic analyses revealed the isolated bacterium as a new species of Alkalihalobacillus. Comparative analysis of the contents of carbohydrate-active enzymes revealed various a-amylases, each with its respective carbohydrate-binding module for starch hydrolysis. Functional analysis identified the hydrolysis of starch and the maltooligosaccharides maltose and dextrin into D- and UDP-glucose. The fastest growth and a-amylase production occurred at 3% salinity at a temperature of 30°C. The Alkalihalobacillus sp. consists of exclusive contents of a-amylases and other enzymes that may be valuable in the hydrolysis of the algal polysaccharides cellulose and laminarin.