Bioactive stilbenes from a Bacillus sp. N strain associated with a novel rhabditid entomopathogenic nematode

Abstract

Aims: The aim of the present study was to purify and characterize a natural antimicrobial compound from Bacillus sp. strain N associated with a novel rhabditid entomopathogenic nematode. Methods and Results: The cell‐free culture filtrate of a bacterium associated with a novel entomopathogenic nematode (EPN), Rhabditis (Oscheius) sp. exhibited strong antimicrobial activity. The ethyl acetate extract of the bacterial culture filtrate was purified by column chromatography, and two bioactive compounds were isolated and their chemical structures were established based on spectral analysis. The compounds were identified as 3,4′,5‐trihydroxystilbene (1) and 3,5‐dihydroxy‐4‐isopropylstilbene (2). The presence of 3,4′,5‐trihydroxystilbene (resveratrol) is reported for the first time in bacteria. Compound 1 showed antibacterial activity against all the four test bacteria, whereas compound 2 was effective against the Gram‐positive bacteria only. Compounds 1 and 2 were active against all the five fungi tested and are more effective than bavistin, the standard fungicide. The antifungal activity of the compounds against the plant pathogenic fungi, Rhizoctonia solani is reported for the first time. Conclusions: Cell‐free extract of the bacterium and isolated stilbenes demonstrated high antibacterial activity against bacteria and fungi especially against plant pathogenic fungi. We conclude that the bacterium‐associated EPN are promising sources of natural bioactive secondary metabolites. Significance and Impact of the Study: Stilbene compounds can be used for the control of fungi and bacteria.

Molecular characterization and amplified ribosomal DNA restriction analysis of entomopathogenic bacteria associated with Rhabditis (Oscheius) spp.

“…Two stilbenes viz 3,4′,5-trihydroxystilbene and 3,5-dihydroxy-4-isopropylstilbene with antimicrobial activity were also isolated from the same bacterium associated with Rhabditis ( Oscheius ) sp. (Kumar et al 2012b ). Tryptophan containing diketopiperazines viz cyclo-( l -Trp- l -Pro), cyclo-( l -Trp- l -Tyr), cyclo-( l -Trp- l -Ile), cyclo-( l -Trp- l -Leu) and cyclo-( l -Trp- l -Phe) with antibacterial activity against human pathogenic bacteria were isolated from Comamonas testosteroni associated with R. ( Oscheius ) sp.…”

Resveratrol—Potential Antibacterial Agent against Foodborne Pathogens

“…It is a compound present in grape skins and wine, and is known to exhibit multi-spectrum therapeutic applications having been reported to exhibit anticancer, antiangiogenic, immunomodulatory, cardioprotective, and antioxidant activity. Although there is still very limited work on the antibacterial activity of resveratrol, it has been shown that resveratrol exhibits antibacterial activity against several Gram-positive and Gram-negative foodborne bacteria (Chan, 2002 ; Tegos et al, 2002 ; Paulo et al, 2010 ; Paolillo et al, 2011 ; Alvarez et al, 2012 , 2013 ; Kumar et al, 2012b ; Plumed-Ferrer et al, 2013 ; Augustine et al, 2014 ; Ferreira et al, 2014 ; Moran et al, 2014 ; Promgool et al, 2014 ; Subramanian et al, 2014 ; Duarte et al, 2015 ; Kim et al, 2015 ; Makwana et al, 2015 ; Ferreira and Domingues, 2016 ; Liu et al, 2016 ; Seukep et al, 2016 ; Silva et al, 2016 ; Surendran Nair et al, 2016 ; Klancnik et al, 2017 ; Lai et al, 2017 ; Lee and Lee, 2017 ; Oliveira et al, 2017 ). This review aims to provide an overview of the published data on the antibacterial activity of resveratrol against foodborne pathogens, its mechanisms of action as well as its possible applications in food packing and processing; in addition we also summarize the current data on its potential synergism with known antibacterials and future research and applications.…”

Regulation of stilbene biosynthesis in plants

“…from Vitis vinifera, Shi et al 2012; Alternaria sp. from a mangrove plant Myoporum bontioides; Wang et al 2014b), emtomopathogenic bacteria (Photorhabdus luminescens, Eleftherianos et al 2007; Bacillus sp., Kumar et al 2012), several edible mushrooms (Peng et al 2015), sponge (Antarctic sponge Kirkpatrickia variolosa, Jayatilake and Baker 1995), and moth larva (dried silkworm larva of Bombyx mori, Kikuchi et al 2004). A recent transcriptome analysis provided the evidence at the gene level that stilbenes in the endophytic fungus Alternaria could be synthesized by CHS (Che et al 2016), and a recent structural analysis revealed that the stilbene 2-isoprpyl-5-[(E)-2-phenylvinyl] benzene-1,3-diol in bacteria Photorhabdus is synthesized by the collaboration of two enzymes, the unusual b-ketosynthase StlD and the aromatase StlC (Mori et al 2016).…”