Heterotrophic Bacterial Population in Tropical Coastal Waters

Abstract

In shallow coastal waters of tropical areas, bacteria are believed to play an important role in the recycling of matter. Astudy concerning bacterial population in the tropical coastal waters of the East Johore Strait, Singapore was carried out from May to November 1977.
The viable bacteria was enumerated by the spread agar plate technique; their numbers ranged from less than 1.0×10³ to 1.8×10⁵ c. f. u./ml. Pseudomonas, Vibrio and Flavobacterium are the dominant genera in the Strait. They comprised 57.1% of the isolated bacteria.
Most (90.3%) of the 93 strains were asporogenous gram-negative rods and 78.5% required NaCl for growth. Motile bacteria (83.9%) with polar or peritrichous flagella were more plentiful than non-motile bacteria. Almost 42% of the isolates were chromogenic and about 31% could reduce nitrate to nitrite. About 46% of the bacterial strains were capable of decomposing tri-butyrin, 20% could degrade casein, 22% liquefy gelation, and only 12% hyfrolyse starch.