Alkaliphilic, Alkalitolerant Microorganisms

Abstract

AbstractAlkaliphilic microorganisms are those microbes that require alkaline pH for growth with optimum growth at pH 9.0. They cannot grow or grow only slowly at near neutral pH. Alkalitolerant microorganisms can grow at alkaline pH at 9–10 but can also grow at neutral pH. They occur in soda lakes, alkaline wastewaters, commercial process effluents, etc. To cope up with the alkaline environment, they maintain internal pH 7.0–8.5, possess acidic polymers in cell wall components, and use sodium ions for solute transport through membrane. Alkaliphilic bacteria are widely distributed in nature and represented by Bacillus alcalophilus, cyanobacteria, Proteobacteria, and archaea. Alkaliphilic bacteria are more explored for their alkaline enzymes, exopolysaccharides (EPS), polyhydroxyalkanoate (PHA), and bioremediation of alkaline wastewaters.In India, alkaliphilic microorganisms have been extensively studied from the alkaline soda lake of Lonar and explored for production of EPS, PHA, hydrolytic enzymes and antimicrobial compounds, and bioremediation of alkaline wastewaters. Alkaliphilic microorganisms have also been reported from alkaline soils, alkaline wastewaters from chemical industries, etc. from different parts of India. Three new genera and nine novel species of alkaliphilic microorganisms have been described, thus contributing to the knowledge of alkaliphiles, new to Science, from India.KeywordsAlkaliphilicAlkalitolerantSoda lakesAlkaline wastewaterspH homeostasisAcidic polymers Alkalibacillus CyanobacteriaAlkaline enzymesLonar LakePolyhydroxyalkanoateExopolysaccharide