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Background There is growing evidence that some devastating biotic invasions are facilitated by microbial symbionts. The red turpentine beetle (RTB), an innocuous secondary insect attacking weakened trees in North America, has formed an invasive complex with the fungus Leptographium procerum in China, and this invasive beetle-fungus symbiotic complex is capable of attacking and killing healthy pines. A previous study demonstrated that three Chinese-resident fungi, newly acquired by RTB in China, induce high levels of a phenolic defensive chemical, naringenin, in pines and this invasive beetle-fungus complex is suppressed by elevated levels of naringenin while the beetle uses its gallery as an external detoxification system in which particular yeast-like fungi and bacterial species biodegrade naringenin. However, the functional roles of key microbial players in the symbiosis, contained within the microbiome of the bark beetle gallery, have not been well elucidated. Results In this report, the symbiotic naringenin-degrading microbiota were found to increase RTB survivorship in the presence of induced host defenses, and potential genes associated with degradation pathways were discovered. While fungi in the gallery microbiota had little involvement in naringenin degradation, bacterial community structure within the beetle gallery was highly correlated to naringenin degrading activity. Phylotypes of the Gram-negative bacterial genus Novosphingobium , which possessed genes involved in degradation pathways, were highly correlated to naringenin degradation activities and RTB associated with an isolated species of this genus acquired protection against naringenin and gained fitness. Conclusions Our results demonstrated that symbiotic bacterial community of RTB galleries enhances the survivorship and overall fitness of invasive beetles by degrading the host phenolic naringenin, ultimately overcoming the tree defenses and facilitating the success of the invasive beetle-fungi complex. This dynamic interplay between the invasive insect pest and multipartite microbes suggests a putative mechanism in invasion ecology for mitigating biotic resistance to symbiotic invasion.

Background Gut symbiotic microbiota plays a critical role in nutrient supply, digestion, and absorption. The bamboo snout beetle, Cyrtotrachelus buqueti, a common pest of several bamboo species, exhibits high lignocellulolytic enzyme activity and contains various CAZyme genes. However, to date, no studies have evaluated the role of gut symbiotic microbiota of the snout beetle on bamboo lignocellulose degradation. Therefore, the present study investigated the role of gut symbiotic microbiota of C. buqueti on bamboo lignocellulose degradation. Results Gut symbiotic microbiota of female (CCJ), male (XCJ), and larvae (YCJ) beetles was used to treat bamboo shoot particles (BSPs) in vitro for 6 days. Scanning electron microscopy (SEM) revealed significant destruction of the lignocellulose structure after treatment, which was consistent with the degradation efficiencies of CCJ, XCJ, and YCJ for cellulose (21.11%, 17.58% and 18.74%, respectively); hemicellulose (22.22%, 27.18% and 34.20%, respectively); and lignin (19.83%, 24.30% and 32.97%, respectively). Gut symbiotic microbiota of adult and larvae beetles was then identified using 16sRNA sequencing, which revealed that four microbes: Lactococcus, Serratia, Dysgonomonas and Enterococcus, comprise approximately 84% to 94% of the microbiota. Moreover, the genomes of 45 Lactococcus, 72 Serratia, 86 Enterococcus and 4 Dysgonomonas microbes were used to analyse resident CAZyme genes. These results indicated that gut symbiotic microbiota of adult and larvae C. buqueti is involved in the lignocellulose degradation traits shown by the host. Conclusions This study shows that the gut symbiotic microbiota of C. buqueti participates in bamboo lignocellulose degradation, providing innovative findings for bamboo lignocellulose bioconversion. Furthermore, the results of this study will allow us to further isolate lignocellulose-degrading microbiota for use in bamboo lignocellulose bioconversion.

Amphibians are the most severely threatened vertebrate group in terms of biodiversity. The microbiota that coexist in a mutualistic relationship with amphibians play a crucial role in shaping their health status, reproductive efficiency, and environmental adaptability. Understanding the relationship between amphibians and microbiota is vital for elucidating the causes of amphibian diseases and developing effective prevention and control techniques, which in turn is significant for enhancing the effectiveness of amphibian diversity conservation. The main findings of this article are as follows: Firstly, it provides an overview of the systematic assessment and analysis methods regarding the importance of amphibians and their symbiotic microbiota, detailing the primary research techniques currently employed. Secondly, it discusses the impacts of environmental and biological factors on the characteristics of amphibian symbiotic microbial communities, including dimensions such as altitude, temperature fluctuations, and host dietary habits. Finally, the future directions of research on amphibian symbiotic microbiota are examined, with five recommendations presented: (1) Establish a comprehensive sample library and database of amphibians and their symbiotic microbiota to create a solid foundation for scientific research. (2) Explore the coevolutionary paths between amphibians and symbiotic microbiota to clarify the dynamic evolutionary patterns and principles of their interactions. (3) Strengthen research on specific areas of amphibians, especially the microbial communities in the oral cavity and cloaca. (4) Enhance research on the symbiotic microbiota of the Gymnophiona. (5) Strengthen international cooperation to build cross-border research platforms and jointly promote the rapid development of global amphibian symbiotic microbiology. This article summarizes the current research progress on the interaction between amphibians and their symbiotic microbiota (not necessarily mutualistic). It discusses the conservation of amphibian biodiversity from the perspective of their symbiotic microbial communities and provides a forward-looking analysis of future research directions. It aims to provide rich background information for understanding the complexity of this symbiotic system, while also having significant value in enhancing the effectiveness of amphibian biodiversity conservation.

The synergistic effects of stratospheric ozone depletion and climate change are intensifying surface ultraviolet-B (UVB) radiation, posing a severe threat to amphibians—one of the most endangered vertebrate groups globally. Xenopus laevis, with its cutaneous respiration and limited photoprotective mechanisms, exhibits high sensitivity to UVB, making it a suitable model for ecotoxicological studies. While UVB is known to cause DNA damage, immune suppression, and microbial dysbiosis, its mechanisms in multi-organ interactions, dose–response thresholds, and host–microbiome regulatory networks remain poorly understood. This study employed a gradient UVB exposure regime integrated with histopathology, oxidative stress assays, and 16S rRNA sequencing to systematically evaluate the effects of UVB on (1) cascade damage across skin, liver, and intestinal barriers; (2) immune cell distribution; (3) redox dynamics; and (4) microbial community structure and function. Our findings demonstrate that low-dose UVB activated compensatory antioxidant defenses without structural disruption, whereas exposure beyond a critical threshold induced nonlinear redox collapse, microbial dysbiosis, and multi-organ barrier failure, collectively exacerbating ecological adaptation risks. These results reveal a cross-scale mechanism by which UVB impairs amphibian health via disruption of host–microbe homeostasis, providing a conceptual and empirical framework for assessing species vulnerability under ongoing climate change.

[This corrects the article DOI: 10.1371/journal.pone.0298917.].

Background Symbiotic microbiota in vertebrates play critical roles in establishing and enhancing host resistance to pathogenic infections as well as maintaining host homeostasis. The interactions and mechanisms of commensal microbiota-mediated mucosal immune systems have been extensively studied in mammals and, to a lesser extent, in birds. However, despite several studies emphasizing the role of mucosal microbiota in controlling pathogen infections in teleost fish, limited knowledge exists regarding the core microbiota and the mechanisms by which they contribute to resistance against viral infections. Results Our findings suggest that viral infections shape clinical manifestations of varying severity in infected fish. An increased abundance of Bacillus spp . in the mild phenotype indicates its crucial role in influencing fish immunity during viral infections. To confirm that Bacillus spp. act as a core contributor against viral infection in fish, we isolated a representative strain of Bacillus spp. from largemouth bass ( Micropterus salmoides ), which was identified as Bacillus velezensis (Bv), and subsequently conducted feeding trials. Our study demonstrated that dietary supplementation with Bv significantly reduced mortality from largemouth bass virus (LMBV) infection in bass by enhancing host immunity and metabolism as well as by regulating the microbial community. Furthermore, multi-omics analysis elucidated the mechanism by which Bacillus spp . confer resistance to viral infections by regulating the production of diglyceride (DG) during lipid metabolism. Conclusions Our study provides the first evidence that Bacillus spp. are a core microbiota for combating viral infections in teleost fish, shedding light on the conserved functions of probiotics as a core microbiota in regulating microbial homeostasis and mucosal immunity across the vertebrate lineage.

Symbiotic bacteria play a pivotal role in the biology and ecology of herbivorous insects, affecting host growth and adaptation. However, the effects of host identity on the symbiotic microbiota of gall-inducing insects remain less explored. In this study, we utilized high-throughput sequencing to investigate the effects of different oak hosts on the structure and diversity of the symbiotic microbial community in the asexual larvae of the gall-inducing wasp Trichagalma acutissimae. Host plant species significantly altered the alpha and beta diversity of symbiotic microbiota of T. acutissimae. At the phylum level, Proteobacteria was the predominant microflora in both groups, with significantly higher abundance in larvae parasitizing Quercus acutissima than in those parasitizing Q. variabilis. Pseudomonas, which has been identified as responsible for tannin decomposition, was the most dominant genus in T. acutissimae larvae infesting both hosts. LEfSe analysis revealed substantial differences in the symbiotic microbial communities between the two hosts while also highlighting some commonalities. Functional prediction analysis indicated no significant difference in the functional roles of symbiotic bacteria between larvae infesting the two hosts. These findings suggest that the symbiotic microbiome of T. acutissimae larvae is influenced by host plant species, yet different microbial compositions may perform similar functions, implying the potential role of symbiotic microbiota in the adaptation to high-tannin oak leaves. This research enhances our understanding of the symbiotic relationship between forest pests and their associated microbes.

Symbiotic microbiota significantly influence the development, physiology, and behavior of their hosts, and therefore, they are widely studied. However, very few studies have investigated the changes in symbiotic microbiota across generations. Daphnia magna originating from the Qinghai–Tibetan Plateau were cultured through seven generations in our laboratory, and the symbiotic microbiota of D. magna were sequenced using a 16S rRNA amplicon to analyze changes in the structure and functional properties of the symbiotic microbiota of D. magna from a harsh environment to an ideal environment. We detected substantial changes in the symbiotic microbiota of D. magna across generations. For example, the genus Nevskia, a member of the gamma-subclass Proteobacteria, had the highest abundance in the first generation (G1), followed by a decrease in abundance in the fourth (G4) and seventh (G7) generations. The gene functions of the microbiota in different generations of D. magna also changed significantly. The fourth generation was mainly rich in fatty acyl-CoA synthase, acetyl-CoA acyltransferase, phosphoglycerol phosphatase, etc. The seventh generation was mainly rich in osmotic enzyme protein and ATP-binding protein of the ABC transport system. This study confirms that the alterations in the structure and functional properties of the symbiotic microbiota of D. magna under changing environments are typical responses of D. magna to environmental changes.

Paddlefish has high economic and ecological value. In this study, microbial diversity and community structure in intestine, stomach, and mouth of paddlefish were detected using high-throughput sequencing. The results showed that the diversity and richness indices decreased along the digestive tract, and significantly lower proportion of those were observed in intestine. Firmicutes, Bacteroidetes and Proteobacteria were the dominant phyla. In top 10 phyla, there was no significant difference in mouth and stomach. But compared with intestine, there were significant differences in 8 of the 10 phyla, and Firmicutes and Bacteroidetes increased significantly, while Proteobacteria decreased significantly. There was no dominant genus in mouth and stomach, but Clostridium_sensu_stricto_1 and uncultured_bacterium_o_Bacteroidales was predominant in intestine. In conclusion, the species and abundance of microbiota in the mouth and stomach of paddlefish were mostly the same, but significantly different from those in intestine. Moreover, there was enrichment of the dominant bacteria in intestine.