Of 116 chitinolytic actinomycetes, previously isolated from marine sediments, 85 were found to possess antimicrobial activity. A high correlation was noted between chitinolysis and bioactivity. A majority of them suppressed the growth of Gram-positive bacteria but only a few inhibited Gram-negative strains and almost one-half of them exhibited antimycotic activity. Several of the last group yielded polyenes of which heptaenes were the most commonly occurring ones. Other strains synthesized detectable amounts of fl-lactam antibiotics. It is suggested that chitinolysis may serve as an indicator of potential bioactivity among marine actinomycetes.tinomycetes to hydrolyze chitin (Hsu and Lockwood 1975). Based on this observation, we recently surveyed our collection of marine actinomycetes for chitinolytic activity and found that many of the strains share this property. Consequently, part of our collection has been divided into an easily definable cluster based on a common secretory property, namely the elaboration of chitinases.In the present investigation, we have attempted to ascertain if chitinolytic activity may be related to the synthesis of antimicrobial substances. Toward this end, 116 chitinolytic strains were grown in submerged culture and analyzed for the production of antibacterial a n d / o r antifungal compounds.
This is a descriptive study of a series of laboratory exercises on environmental microbiology carried out by students in a general microbiology course during eight of the twelve weeks of the semester. The revised laboratory component is predicated upon seawater and sediment samples collected by student pairs using marine sampling equipment on a field trip aboard a research vessel. Two longitudinal studies were performed: assay for antibiotic production from isolated actinomycetes and construction and observation of Winogradsky columns. Two additional experiments: culturing microalgae and water testing for coliforms also used the samples collected by the students. The advantages of long-term, challenging laboratory experiences actively involving the students in group process, self-direction, and scientific practices are discussed. Also considered are development of laboratory skills, scientific competencies, and students’ self-confidence in carrying out such environmental investigations. Plans for future assessment of student learning are presented.
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