Ecological Studies On The Bacteria In Semi-closed Hatchery Of Penaeus Chinensis Larvae And Inhibition Of Diseased Bacteria By Microalage

In the semi-closed hatchery studied in the present investigation,the number of adhered bacteria on the Chinese shrimp eggs is about 140 17.1 cfu/egg. Bacteria Pseudomonas sp.,Aeromonas sp. and Cytophage sp. were the most general.when treated using ozone ,the number of bacteria descended to 35 5.6 cfu/egg in 1 minute,and all were removed in 3 minutes.In larval rearing water of semi-closed hatchery,total viable heterotrophic bacteria counts ranged from 0.5 104 to 2.95 105 cfu./ml.At the preliminary stage,the number of heterotrophic bacteria descened ,but asscended totally in the latter.Among them,Pseudomonas. sp. is the most frequently encountered genera, the following is Aeromonas sp., Vibrio Sp.and Flavobacterium sp..About the relationship between microalage and bacteria, Isochrysis galbana, Phaeodactylum tricornutum Bohlin and Tetraselmis chuii's extracellular products, aqueous phase and Tetraselmis chuii's organic phase can inhibit pathogenic strains of Vibro anguillarum. Isochrysis galbana and Phaeodactylum tricornutum Bohlin's aqueous phase, Isochrysis galbana, Phaeodactylum tricornutum Bohlin and Tetraselmis chuii's organic phase can inhibit pathogenic strains of Pseudomonas sp..Towards pathogenic strains of Vibro Harvey,only Isochrysis galbana's organic phase show inhibitory activity.When the microalage' s density is about 10,000 cell/ml in larval rearing water, Isochrysis galbana, Phaeodactylum tricornutum Bohlin and Tetraselmis chuiishow great inhibitory activity on bacteria.