Diversity Analysis And Screening Of Antimicrobial And Antitumor Halophiles

The aim of this study was to exploit cultivable halophiles from solar saltern and to investigate their potential antimicrobial and antitumor activities.Halophiles were isolated from sediment and saline water collected from Weihai Solar Saltern in Weihai of Shandong Province. The effect of salt concentration on the growth of isolated halophilic strains was determined in order that all the strains can be classified into one of three groups of halophiles. The identification and phylogenetic analysis of the isolated halophiles were determined by their morphological characteristics and molecular identification. The potential antimicrobial activities of the isolated halophilic strains for different indicator strains were screened. MTT analysis was performed to determine the potential cytotoxic activity of the crude extract of the isolated halophiles.A total of 45 bacterial strains, 28 fungal strains and 38 actinomycetic strains were isolated and most of them displayed moderately halophilic characteristics. Phylogenetic analysis of halophilic bacteria indicated that 17 of the isolated strains were related to the phylum Firmicutes and belonged to four genera, Bacillus, Halobacillus, Planococcus and Salinicoccus. The other strains identified as genus of Halomonas belonged to the phylumγ-Proteobacteria. All the halophilic fungi were related to the subphylum Deuteromycotina belonged to the phylum Eumycota, and there were 9 and 19 fungal strains belonged to two genera, Aspergillus and Penicillium, respectively. All the halophilic actinomycetes were related to the phylum Actinobacteria, and a majority of halophilic actinomycetes belonged to genus of Streptomyces.Most of the halophilic bacterial strains showed potent activities against Gram-positive bacteria, human pathogenic fungi and plant pathogenic fungi. The halophilic fungal strains showed potent activities against Gram-positive and Gram-negative bacteria. In addition, the crude extracts from 14 halophilic bacterial strains, 13 halophilic fungal strains and 20 halophilic actinomycetic strains showed cytotoxic activity against tumor cells Bel 7402.Our results suggest that the halophiles may be developed as promising sources for the discovery of novel bioactive substances.