Screening of bioactive compounds produced by streptomyces spp. Isolated from eastern honey bee (apis cerana) and stingless bee (tetragonula laeviceps)

Abstract

In recent years, antibiotic-resistant pathogens have been increasing faster than the numbers of new therapeutic compounds entering clinical use, thus the search for new antibiotics is in need. Apart from diseases caused by pathogenic microorganisms, obesity and overweight are linked to deaths worldwide. The search for drugs that can reduce the number of fat cell is also necessary in public health. One of the widespread sources of antibiotics is Actinomycetes, especially Streptomyces genus. Streptomyces spp. have been extensively isolated from soil but the discovery of novel compound is rare. Therefore, Streptomyces isolation from rare niche, i.e. symbionts of insects, could potentially lead to the discovery of novel bioactive compounds. In this study, Eastern honey bees (Apis cerana) and stingless bees (Tetragonula laeviceps) were used as sources to isolate Streptomyces and total of 125 isolates were obtained from internal and external. We found that five isolates produced the metabolites with broad antimicrobial activity against tested species of Gram positive bacteria, Gram negative bacteria and yeast. The phylogenetic tree based on 16s rRNA gene sequences showed high similarity with previously discovered microorganisms. Moreover, the results implied that the evolution which Streptomyces spp. isolated from the same insect were not root together. We have investigated the effects of the crude metabolites on preadipocytes cell line 3T3-L1 differentiation and found that crude extracted from I-EHB-18, closely related to Streptomyces andamanensis sp. Nov, inhibited adipocyte differentiation of 3T3-L1 cells at the early stage of differentiation with no acute cytotoxicity. Detailed study revealed that this crude extract suppressed expression of Peroxisome proliferator-activated receptor gamma (PPARγ), a master regulator of adipocyte differentiation. This is the first report of bioactive compound possessing anti-adipocyte differentiation activity produced by Streptomyces isolated from Eastern honey bees. Hence, the result may lead to a new compound for developing therapeutic drugs in the future.