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Research Journal of Microbiology
  Year: 2017 | Volume: 12 | Issue: 4 | Page No.: 218-228
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Antimicrobial and Insecticidal Activities of n-Butanol Extracts from Some Streptomyces Isolates

Maher Obeidat , Saeed Abu-Romman, Nidal Odat, Moawiya Haddad, Amal Al-Abbadi and Azmi Hawari

Background: Increasing antibiotic resistance and the appearance of multidrug-resistant pathogenic strains of bacteria and fungi are becoming a serious global problem. The use of biological insecticides instead of the chemical insecticides has been increased because of their safety, specificity and biodegradability. Objectives: The objectives of the study were to identify Streptomyces isolates screened from soil and to determine their antibacterial, antifungal and insecticidal activities. Materials and Methods: Streptomyces isolates collected from soils in various habitats of Jordan were cultured on Starch-Casein-Nitrate Agar (SCNA) medium and identified based on their morphological and cultural characteristics. Tryptone Soy Broth (TSB) cultures of isolates were extracted by n-butanol and screened for their antibacterial and antifungal activities using the agar-well diffusion method. Furthermore, the extracts were examined for their insecticidal activity against Drosophila melanogaster using conventional bioassay protocol. The LC50 values of extracts at 95% confidence interval were determined by probit analysis. Results: In total, 127 Streptomyces isolates were isolated from Jordanian soils with white aerial mycelia and rectus-flexous sporophores being dominant. It was found that the n-butanol extracts of 37 Streptomyces isolates prepared from cultures that were grown in TSB medium, which was considered as the most suitable medium in this study for the production of antimicrobial activity, exhibited antibacterial and/or antifungal activities on multidrug resistant microorganisms. Interestingly, it was observed that 11 isolates exhibited antibacterial activity on MRSA. It was also found that none of the isolates which displayed orange, red and yellow aerial mycelia produced antimicrobial activity. On the other hand, 19 isolates divided into seven color series exhibited insecticidal activity against D. melanogaster. The insecticidal activity of combined crudes of the most significantly toxic Streptomyces isolate S2 and Bacillus thuringiensis subsp. israelensis J63 was higher than that produced from either S2 or J63. Based on the interspacer region 16S-23S rRNA gene sequence analysis, the sequence alignment of the selected isolates had the greatest possible identity to Streptomyces and are grouped into two subclusters in the phylogenetic tree. Conclusion: Streptomyces cultures obtained from TSB medium have an increased and a promising antimicrobial activity against multidrug-resistant pathogens. Combined crudes of Streptomyces and B. thuringiensis produced competitive insecticidal activity.
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How to cite this article:

Maher Obeidat, Saeed Abu-Romman, Nidal Odat, Moawiya Haddad, Amal Al-Abbadi and Azmi Hawari, 2017. Antimicrobial and Insecticidal Activities of n-Butanol Extracts from Some Streptomyces Isolates. Research Journal of Microbiology, 12: 218-228.




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