Title

PRODUCTION AND PARTIAL PURIFICATION OF THREE LYTIC ENZYMES FROM AN ARTHROBACTER SP. LYSING CELLS OF FUSARIUM ROSEUM

Date of Completion

January 1981

Keywords

Biology, Microbiology

Degree

Ph.D.

Abstract

The extracellular enzyme complex from an Arthrobacter sp. was investigated. The bacteria, designated Arthrobacter P-35, was previously shown to actively lyse Fusarium roseum hyphae and was correlated with biological control of carnation stem rot caused by Fusarium roseum. Heat-killed Fusarium cells were lysed by cell-free culture fluid of Arthrobacter P-35 after the organism had been grown on the same material. Examination of the culture fluid yielded significant levels of enzyme activities of chitinase, laminarinase, protease, n-acetyl-(beta)-D-hexosaminidase, and (beta)-D-glucosidase. The chitinase, laminarinase and protease were regarded as primary in their mode of attack and were studied in detail using batch culture techniques. Significant production of the enzymes did not occur until the late logarithmic or early stationary phase. Maximum chitinase production resulted after 7 days when Arthrobacter P-35 was grown on Fusarium cells at a concentration of 20 mg/ml. Likewise, maximum laminarinase and protease production took place at 10 mg/ml after 4 and 7 days respectively. The amount of n-acetylglucosamine, glucose and protein found in the culture supernatant was correlated with the levels of lytic enzymes produced. Chitinase, laminarinase and protease were partially purified through ammonium sulfate precipitation followed by Sephadex gel filtration. These results indicate that Arthrobacter P-35 possesses the enzymatic capacity to lyse Fusarium roseum cells and lends support to heterolysis as a mechanism of biological control. ^