Isolation and screening of antibacterial and enzyme producing marine actinobacteria to approach probiotics against some pathogenic vibrios in shrimp Litopenaeus vannamei
Description:1-Persian Gulf and Oman Sea Ecological Research Center, Iranian Fisheries Science Research Institute (IFSRI), Agricultural Research, Education and Extension Organization (AREEO), Bandar Abbas, Tehran, Iran. 2-Department of Microbiology- College of Science, Agriculture and Modern Technologies- Shiraz Branch- Islamic Azad University- Shiraz- Iran. 3-Iranian Fisheries Science Research Institute (IFSRI), Agricultural Research, Education and Extension Organization (AREEO), Tehran- Iran * Corresponding author's Email:
The application of new probiotics is a good strategy in the biological control of infectious diseases in aquaculture. Approximately 100 marine actinobacteria isolates were obtained from 10 sediment samples of shrimp farms. Heat treatment of sediment samples resulted in a selective reduction of the non actinobacterial heterotrophic microflora. Starch nitrate agar mediumexhibited more efficacy than glycerol arginine agar medium for isolation. Twenty seven percent of actinobacterial isolates showed antagonistic activities against pathogenicVibriospp.All the antagonistic isolates showed the typical morphology of genusStreptomyces. Exoenzymatic activity screening showed that 44%, 26%, 37% of antagonistic isolates represented amylase, lipase and protease activities, respectively. MNM-1400 strain exhibited highest antagonistic and exoenzymatic activity. The pathogenicity experiment revealed that MNM-1400 strain did not cause disease inLitopenaeus vannamei larvae. Extraction of produced antibacterial compounds by MNM-1400 strain showed that the active constituent didn’t have non polar property. Morphological, physiological and biochemical identification confirmed that MNM-1400 strain belonged to the genusstreptomyces. Phylogenetic analysis by 16S rRNA gene sequencing showed a high similarity between MNM-1400 strain andStreptomyces californicus (similarity: 99%). These results suggest that the MNM-1400 strain can be considered as a potential probiotic in aquaculture.
Keywords: Probiotic, Marine actinobacteria, Biological control, Shrimp,Litopenaeus vannamei
Author:Gozari M.1, 2*; Mortazavi M.S.1; Bahador N.2; Tamadoni jahromi S.1; Rabbaniha M.3
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