Studies in Bacterial Chemoreception. I. The Effect of Biogenic Amines and Cannabinoids on Bacterial Chemoreception. II. Chemotactic and Growth Responses of Marine Bacteria to Algal Extracellular Products.
HARVARD UNIV CAMBRIDGE MASS DIV OF ENGINEERING AND APPLIED PHYSICS
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The chemotactic response of Pseudomonas fluorescens was significantly enhanced by the stimulants d-1-amphetamine and epinephrine. Acetylcholine, a physiological antagonist of epinephrine, and the cannabinoid tetrahydrocannabinol inhibited bacterial chemotaxis. It may be possible to use bacterial chemotaxis as a bioassay in biochemical studies of drug action. The possibility that planktonic algae possess a phycosphere, a zone surrounding them created by the production of extracellular products which may serve as bacterial nutrients, is examined. Bacterial growth in algal cultures to which no additional organic material is added is greatest only as the cultures age and algal cell lysis becomes obvious. Marine bacterial isolates are chemotactic to filtrates from algal cultures, but the response is significant only to filtrates from old cultures. Specific compounds known to occur as algal extracellular products attract bacteria. The validity of the phycosphere concept and its potential importance to marine microorganisms is discussed. Modified author abstract