Agarase, amylase, cellulase, and chitinase activity at deep-sea pressures

Abstract

An agarase produced by a marine bacterium, a bacterial amylase, a fungal cellulase, and an actinomycetal chitinase were examined for their stability and hydrolytic activity at hydrostatic pressures existing in the deep sea. All four enzymes were from barophobic organisms which fail to grow at pressures exceeding 400 to 500 atm, but some observations were made on the hydrolase activity of barophilic bacteria grown at 500 to 1,150 atm. Al-though differing in the rates at which they catalyzed the hydrolysis of agar, starch, cellulose, and chitin respectively, all four enzymes were found to be active at deep-sea pressures and temperatures. These glycoside hydrolases were found to be much more baroduric than most oxidoreductases, transferases, and ligases (synthetases) which have been investigated. The chitinase andα-amylase were about as stable at 1,000 atm as at 1 atm. Cellulase was also baroduric and active at 1,000 atm at pH 4.2, its pH optimum at 1 atm. The pressure tolerance of cellulase was much less at higher pH values characteristic of normal sea water, i.e., near pH 8.2. The activity of agarase (synthesized at 1 atm) was retarded by increased pressure, due largely to the inactivation of this enzyme system. However, barophilic bacteria, isolated from the deep sea, synthesize agarases which are active at 1,000 atm as indicated by the hydrolysis of agar.