The survey of molecular and antimicrobial activity of isolated bacteria from the Caspian sea

Background and Aim: Marine microorganisms have an astonishing potential for producing antimicrobial substances against pathogenic bacteria. In this study, isolation and measurement of antimicrobial activity among these microorganisms against some pathogenic bacteria was carried out. Materials and methods: Samples were collected in autumn from the west of the Caspian Sea. Isolated samples were purified and antimicrobial activity among these samples against some pathogenic bacteria were measured by the use of two methods. At the end, genetic substance (DNA) of the strains with antimicrobial effect against pathogenic bacteria was extracted and polymerase chain reaction with universal primers was carried out. Isolated strains were identified by molecular method (16SrDNA PCR sequencing) and the strains were submitted and registered as new marine strains in the NCBI. Results: Results showed, the strains with antimicrobial activity had a noticeable effect on gram positive bacteria. So that gram positive bacteria were nearly inhibited in all cases but antimicrobial activity was restricted against gram negative bacteria, because gram negative bacteria were inhibited only in few cases. Finally, identification of stains with antimicrobial effect showed, the strains belong to Bacillus genus. Conclusion: According to this result; we can use marine bacteria for controlling growth of pathogenic bacteria that are resistant to drugs and as a big threat for the human health. Also we can optimize conditions for producing antimicrobial substances among them and we can extract them in industrial conditions for increasing quality and quantity antimicrobial substances in these bacteria for the use in different industries such as pharmaceutical industry

Measurement of antimicrobial activity of isolated bacteria from the Caspian sea and molecular identification of strains with antimicrobial effect

Introduction: Easy access and wide use of antimicrobial compounds led to the emergence of resistance among microorganisms. Therefore, screening and identifying antimicrobial compound with high effect of microorganisms in different environments is necessary and vital . Using microorganisms for biological aims change them to an important tool to control pathogens. Streptomyces griseus is one of them. The aim of this study is isolation of marine bacteria with antimicrobial effect against gram positive and negative bacteria. Finally, molecular identification of strains with antimicrobial activity. Materials and methods: In this study, 162 strains were isolated from the Caspian Sea .The strains were cultured on special medium and finally antimicrobial activity on references strains as measured. Among them four strains with remarkable antimicrobial activity were identified and selected. The strains were subjected to 16S rDNA PCR sequencing. The strains were submitted to NCBI as new Streptomyces griseus strains. Results: Among 162 strains, 4 strains had the most antimicrobial activity. The result showed, the strains were the most effective on Bacillus subtilis and Staphylococcus aureus (Gram positive bacteria) and the least effect were observed on Escherichia coli and Pseudomonas aeruginosa (Gram negative bacteria). After sequencing, the strains were classified to sterptomyces griseus genu. Discussion and conclusion: In this study, 4 strains with antimicrobial activity were identified. According to the strength of these bacteria for controlling pathogenic bacteria resistant to antibiotic, we can have more pure microorganisms in optimized and controlled conditions for using in pharmaceutical industries and also for the treatment of dangerous pathogenic bacteria