Plattner, B. L. | Search bioRxiv

bioRxiv2025

The potential of Clonostachys rosea as a biolarvicide against Anopheles gambiae

Mosquitoes vector multiple disease-causing pathogens detrimental to humans, imposing a high public health and economic burden. Chemical and biological larvicides are used in some settings to reduce mosquito populations as a supplement to adult population control. In this study, we assessed the larvicidal potential of a newly isolated strain of the hypocrealean fungus, Clonostachys rosea, by modifying a previously established laboratory-based experimental design. This design allowed us to distinguish between the larvicidal impact of the fungal culture supernatant and conidia. Our data show that C. rosea efficiently kills larvae of the African malaria mosquito, Anopheles gambiae, at an LC50 of 7.78 x 106 for culture supernatant and 7.13 x 107 conidia/mL for washed conidia. Fungal culture supernatant retained over 95% of its activity upon autoclaving, suggesting a temperature stable non-proteinaceous mycotoxin is responsible for larvicidal activity in the supernatant. Conidia were readily ingested, remained in the gut lumen, and did not germinate or translocate to the ectoperitrophic space nor the hemocoel. UV and heat-killed conidia retained larvicidal activity, demonstrating that no active secretion of toxins, fungal growth, or infection is required for killing mosquito larvae. However, autoclaving conidia abolished larvicidal activity, suggesting that larvae may not be killed via a mechanical mechanism, such as occlusion. Instead, our data demonstrate that C. rosea conidia kill An. gambiae larvae via the passive release of intracellular mycotoxins and have potential as a fungal biolarvicide to control An. gambiae populations. HighlightsO_LIClonostachys rosea is a potent larvicide of Anopheles gambiae mosquitoes. C_LIO_LILarvicidal activity from C. rosea culture supernatant is heat stable. C_LIO_LIC. rosea conidia are ingested but remain in the gut lumen and do not germinate. C_LIO_LIC. rosea conidia passively release toxins ultimately leading to larval death. C_LI

microbiology↗

bioRxiv2024

Eubacterium rectale detoxification mechanism increases resilience of the gut environment

Lachnospiraceae members were highly detected in dysbiotic IL-10 KO mice that displayed similar physiological outcomes as control mice. Lachnospiraceae is a highly diverse family of microbes that have been shown to display both commensal and pathogenic characteristics in the colon environment. We investigated the impact of genetic variation in five Lachnospiraceae strains on lowering cellular inflammation and ROS levels. Cell free spent media (CFSM) from Eubacterium rectale resulted in lowered ROS, and nitric oxide levels in stressed colon cells. We demonstrated through an array of multi omics and molecular techniques that glutathione (GSH) biosynthesized by E. rectale was able to alleviate host ROS damage. We further showed downregulation of cell stress and immune response genes by host RNA sequencing, which is evidence that E. rectale microbial products promote recovery and alleviate ROS stress. HighlightsO_LILachnospiraceae detection correlated with lower host inflammation in vertically transmitted dysbiotic mice C_LIO_LICell free spent media from E. rectale lowered ROS and nitric oxide levels when introduced to stressed Caco-2 cells more effectively than 4 other strains of Lachnospiraceae C_LIO_LIEubacterium rectale spent media products include high levels of glutathione (GSH), carbohydrates, and amino acids C_LIO_LIEubacterium rectale potential gene function for glutathione biosynthesis and metabolism found in the genome C_LIO_LILower expression of repair and stress genes of intestinal cells treated with hydrogen peroxide was observed with E. rectale CFSM as well as treatment with 15 mM GSH C_LI

microbiology↗