Antibacterial and cytotoxic metabolites produced by Streptomyces tanashiensis BYF-112 isolated from Odontotermes formosanus

Chemical investigations of the termite-associated Streptomyces tanashiensis BYF-112 resulted in the discovery of four novel alkaloid derivatives: vegfrecines A and B(1 and 2), exfoliazone A(3), and venezueline H(7), in addition to nine known metabolites(4-6, 8-13). The structures of these compounds were elucidated through comprehensive spectroscopic analysis and comparison with existing literature data. Antibacterial assays revealed that viridomycin A(11) exhibited potent antibacterial activity against Staphylococcus aureus, with a zone of inhibition(ZOI) of 12.67 mm, in comparison to a ZOI of 17.67 mm for the positive control gentamicin sulfate. Viridomycin A(11) showed moderate activity against Micrococcus tetragenus and Pseudomonas syringae pv. actinidae, with ZOI values of 15.50 and 14.33 mm, respectively, which were inferior to those of gentamicin sulfate(34.67 and 24.00mm). Viridomycin F(12) also exhibited moderate antibacterial effects against S. aureus, M. tetragenus, and P. syringae pv. actinidae,with ZOI values of 8.33, 16.50, and 10.83 mm, respectively. Cytotoxicity assays demonstrated that viridobruunine A(5), exfoliazone(6), viridomycin A(11), and X-14881E(13) exhibited significant cytotoxicity against human malignant melanoma(A375), ovarian cancer(SKOV-3), and gastric cancer(MGC-803) cell lines, with IC_(50) values ranging from 4.61 to 19.28 μmol·L^(-1). Furthermore, bioinformatic analysis of the complete genome of S. tanashiensis suggested a putative biosynthetic gene cluster(BGC) responsible for the production of compounds 1-12. These findings indicate that the secondary metabolites of insect-associated S. tanashiensis BYF-112hold promise as potential sources of novel antibacterial and anticancer agents.

Exploring the region-wise diversity and functions of symbiotic bacteria in the gut system of wood-feeding termite,Coptotermes formosanus,toward the degradation of cellulose,hemicellulose,and organic dyes

The wood-feeding termite Coptotermes formosanus represents a unique and impressive system for lignocellulose degradation.The highly efficient digestion of lignocellulose is achieved through symbiosis with gut symbionts like bacteria.Despite extensive research during the last three decades,diversity of bacterial symbionts residing in individual gut regions of the termite and their associated functions is still lacking.To this end,cellulose,xylan,and dye-decolorization bacteria residing in foregut,midgut,and hindgut regions of C.formosanus were enlisted by using enrichment and culture-dependent molecular methods.A total of 87 bacterial strains were successfully isolated from different gut regions of C.formosanus which belonged to 27 different species of 10 genera,majorly affiliated with Proteobacteria(80%)and Firmicutes(18.3%).Among the gut regions,37.9%of the total bacterial isolates were observed in the hindgut that demonstrated predominance of cellulolytic bacteria(47.6%).The majority of the xylanolytic and dye-decolorization bacteria(50%)were obtained from the foregut and midgut,respectively.Actinobacteria represented by Dietza sp.was observed in the hindgut only.Based on species richness,the highest diversity was observed in midgut and hindgut regions each of which harbored seven unique bacterial species.The members of Enterobacter,Klebsiella,and Pseudomonas were common among the gut regions.The lignocellulolytic activities of the selected potential bacteria signpost their assistance to the host for lignocellulose digestion.The overall results indicate that C.formosanus harbors diverse communities of lignocellulolytic bacteria in different regions of the gut system.These observations will significantly advance our understanding of the termite–bacteria symbiosis and their microbial ecology uniquely existed in different gut regions of C.formosanus,which may further shed a light on its potential values at termite-modeled biotechnology.

Evaluation of Tung Oil(Vernicia fordii(Hemsl.))for Controlling Termites

In worldwide,the use of chemical pesticides to protect wood has been greatly restricted.In recent years,a large number of researchers devoted to the search for natural,safe and non-polluting bioactive chemical compounds from plants as an alternative to synthetic organic chemical preservative.In Chinese folk,tung oil can be used as paint for wooden furniture to protect them from pests.This study aimed to evaluate the chemical compositions of raw and heated tung oil and their activity against termite.In choice bioassays,weight loss of wood treated with 5%raw or heated tung oil after 4 weeks was significantly less than that of the control group.In no-choice bioassays,there was a significant difference in termite survival and wood weight loss on raw and heated tung oil-treated wood.When tung oil-treatment concentrations increased to 5%,wood weight loss was less than 10%.There was no significant difference in termite survival and wood weight loss between raw and heated tung oil-treated wood.Survival of termites in both tung oil wood treatments was significantly lower than that in the starvation control after 4 weeks.Raw and heated tung oil significantly improved the resistance of pine wood to termites,and have the potential for the development of natural wood preservatives.