Microbial Flora of Pacific Oysters ( Crassostrea gigas ) Subjected to Ultraviolet-Irradiated Seawater

• Published in: Applied Microbiology
• Main Authors: Vasconcelos, G. J., Lee, J. S.
• Format: Article in Journal/Newspaper
• Language: English
• Published: American Society for Microbiology 1972
• Subjects: General Pharmacology, Toxicology and Pharmaceutics; General Immunology and Microbiology; General Biochemistry, Genetics and Molecular Biology; General Medicine; Pacific; Crassostrea gigas
• Online Access: http://dx.doi.org/10.1128/am.23.1.11-16.1972; https://journals.asm.org/doi/pdf/10.1128/am.23.1.11-16.1972

The ability of oysters to purge themselves of microbial contaminants was investigated by identifying the microorganisms retained by oysters after they have been subjected to ultraviolet (UV) light-treated seawater. A UV intensity of 960 μw per min per cm 2 reduced the microbial count of seawater from 263 to 13 per ml. The coliform multitube test (MPN) was reduced from a high of 17 to <0.18 per 100 ml. Over 75% of the microorganisms found in treated seawater were Acinetobacter/Moraxella, Vibrio/Pseudomonas type II, and Flavobacterium/Cytophaga . With the exception of coliforms, the microbial composition of oysters subjected to UV-treated seawater remained at levels comparable to the control oysters held in untreated seawater. Total counts ranged between 10 3 and 10 5 /g. The microorganism most frequently encountered were Flavobacterium/Cytophaga, Vibrio/Pseudomonas type II, Pseudomonas type III or IV, Acinetobacter/Moraxella , gram-positive cocci and Bacillus . Together they comprised over 90% of the flora. Coagulase-positive, deoxyribonuclease-positive, and beta-hemolytic cocci were found in some samples, as were V. parahaemolyticus, V. aliginolyticus , and Aeromonas species.