Nitrogen inhibition of nitrogenase activity involves the modulation of cytosolic invertase in soybean nodule.

Legume symbiotic nitrogen fixation (SNF) is suppressed by inorganic N in the soil. High N inhibition of nitrogenase activity is associated with the deprivation of carbon allocation and metabolism in nodules. However, the underlying molecular mechanisms remain unclear. Here, we identify GmCIN1 which encodes a cytosolic invertase, as a gateway for the N-tuning of sucrose utilization in nodules. GmCIN1 is enriched in mature soybean nodules and its expression is regulated by nitrogen status. The knockout of GmCIN1 using genome editing partially mimicks the inhibitory effects of N on nitrogenase activity and sugar content and the impact of high N on nodule transcriptomes. This indicates that GmCIN1 partially mediates the high N inhibition of nodule activity. Moreover, ChIP-qPCR and EMSA reveal that SNAP1/2 transcription factors directly bind to the GmCIN1 promoter. In addition, SNAP1/2 may be involved in the repression of GmCIN1 expression in mature nodules at high N concentrations. Our findings provide insights into the involvement of the transcriptional tuning of C metabolism genes by N-signaling modulators in the N-induced inhibition of nitrogenase activity.

Reviewing bryophyte-microorganism association: insights into environmental optimization.

Bryophytes, the second-largest group of plants, play a crucial role as early colonizers of land and are a prolific source of naturally occurring substances with significant economic potential. Microorganisms, particularly bacteria, cyanobacteria, fungi form intricate associations with plants, notably bryophytes, contributing to the ecological functioning of terrestrial ecosystems and sometimes it gives negative impact also. This review elucidates the pivotal role of endophytic bacteria in promoting plant growth, facilitating nutrient cycling, and enhancing environmental health. It comprehensively explores the diversity and ecological significance of fungal and bacterial endophytes across various ecosystems. Furthermore, it highlights the moss nitrogen dynamics observed in select moss species. Throughout the review, emphasis is placed on the symbiotic interdependence between bryophytes and microorganisms, offering foundational insights for future research endeavors. By shedding light on the intricate bryophyte-microorganism associations, this study advances our understanding of the complex interplay between plants, microbes, and their environment, paving the way for further research and applications in environmental and biotechnological realms.

Alleviation of H2O2 toxicity by extracellular catalases in the phycosphere of Microcystis aeruginosa.

High levels of environmental H2O2 represent a threat to many freshwater bacterial species, including toxic-bloom-forming Microcystis aeruginosa, particularly under high-intensity light conditions. The highest extracellular catalase activity-possessing Pseudoduganella aquatica HC52 was chosen among 36 culturable symbiotic isolates from the phycosphere in freshly collected M. aeruginosa cells. A zymogram for catalase activity revealed the presence of only one extracellular catalase despite the four putative catalase genes (katA1, katA2, katE, and srpA) identified in the newly sequenced genome (∼6.8 Mb) of P. aquatica HC52. Analysis of secreted catalase using liquid chromatography-tandem mass spectrometry was identified as KatA1, which lacks a typical signal peptide, although the underlying mechanism for its secretion is unknown. The expression of secreted KatA1 appeared to be induced in the presence of H2O2. Proteomic analysis also confirmed the presence of KatA1 inside the outer membrane vesicles secreted by P. aquatica HC52 following exposure to H2O2. High light intensities (> 100 µmol m-2 s-1) are known to kill catalase-less axenic M. aeruginosa cells, but the present study found that the presence of P. aquatica cells supported the growth of M. aeruginosa, while the extracellular catalases in supernatant or purified form also sustained the growth of M. aeruginosa under the same conditions. Our results suggest that the extracellular catalase secreted by P. aquatica HC52 enhances the tolerance of M. aeruginosa to H2O2, thus promoting the formation of M. aeruginosa blooms under high light intensities.

Surviving the stress: Understanding the molecular basis of plant adaptations and uncovering the role of mycorrhizal association in plant abiotic stresses.

Environmental stresses severely impair plant growth, resulting in significant crop yield and quality loss. Among various abiotic factors, salt and drought stresses are one of the major factors that affect the nutrients and water uptake by the plants, hence ultimately various physiological aspects of the plants that compromises crop yield. Continuous efforts have been made to investigate, dissect and improve plant adaptations at the molecular level in response to drought and salinity stresses. In this context, the plant beneficial microbiome presents in the rhizosphere, endosphere, and phyllosphere, also referred as second genomes of the plant is well known for its roles in plant adaptations. Exploration of beneficial interaction of fungi with host plants known as mycorrhizal association is one such special interaction that can facilitates the host plants adaptations. Mycorrhiza assist in alleviating the salinity and drought stresses of plants via redistributing the ion imbalance through translocation to different parts of the plants, as well as triggering oxidative machinery. Mycorrhiza association also regulates the level of various plant growth regulators, osmolytes and assists in acquiring minerals that are helpful in plant's adaptation against extreme environmental stresses. The current review examines the role of various plant growth regulators and plants' antioxidative systems, followed by mycorrhizal association during drought and salt stresses.

Insights into the Early Steps of the Symbiotic Interaction between Soybean (Glycine max) and Sinorhizobium fredii Symbiosis Using Transcriptome, Small RNA, and Degradome Sequencing.

Symbiotic nitrogen fixation carried out by the soybean-rhizobia symbiosis increases soybean yield and reduces the amount of nitrogen fertilizer that has been applied. MicroRNAs (miRNAs) are crucial in plant growth and development, prompting an investigation into their role in the symbiotic interaction of soybean with partner rhizobia. Through integrated small RNA, transcriptome, and degradome sequencing analysis, 1215 known miRNAs, 314 of them conserved, and 187 novel miRNAs were identified, with 44 differentially expressed miRNAs in soybean roots inoculated with Sinorhizobium fredii HH103 and a ttsI mutant. The study unveiled that the known miRNA gma-MIR398a-p5 was downregulated in the presence of the ttsI mutation, while the target gene of gma-MIR398a-p5, Glyma.06G007500, associated with nitrogen metabolism, was upregulated. The results of this study offer insights for breeding high-efficiency nitrogen-fixing soybean varieties, enhancing crop yield and quality.

Elizabethkingia anophelis MSU001 Isolated from Anopheles stephensi: Molecular Characterization and Comparative Genome Analysis.

Elizabethkingia anophelis MSU001, isolated from Anopheles stephensi in the laboratory, was characterized by matrix-assisted laser desorption/ionization time of flight mass spectrometry (MALDI-ToF/MS), biochemical testing, and genome sequencing. Average nucleotide identity analysis revealed 99% identity with the type species E. anophelis R26. Phylogenetic placement showed that it formed a clade with other mosquito-associated strains and departed from a clade of clinical isolates. Comparative genome analyses further showed that it shared at least 98.6% of genes with mosquito-associated isolates (except E. anophelis As1), while it shared at most 88.8% of common genes with clinical isolates. Metabolites from MSU001 significantly inhibited growth of E. coli but not the mosquito gut symbionts Serratia marcescens and Asaia sp. W12. Insect-associated E. anophelis carried unique glycoside hydrolase (GH) and auxiliary activities (AAs) encoding genes distinct from those of clinical isolates, indicating their potential role in reshaping chitin structure and other components involved in larval development or formation of the peritrophic matrix. Like other Elizabethkingia, MSU001 also carried abundant genes encoding two-component system proteins (51), transcription factor proteins (188), and DNA-binding proteins (13). E. anophelis MSU001 contains a repertoire of antibiotic resistance genes and several virulence factors. Its potential for opportunistic infections in humans should be further evaluated prior to implementation as a paratransgenesis agent (by transgenesis of a symbiont of the vector).

Orchid Mycorrhizal Association of Cultivated Dendrobium Hybrid and Their Role in Seed Germination and Seedling Growth.

Orchids are crucial for the horticulture industry. Mycorrhizal fungi benefit crops by improving nutrition, plant growth, and disease resistance. However, the mycorrhizal association of horticultural hybrid orchids is poorly understood. To address this, we investigated mycorrhizal colonization in the entire root system and assessed the mycorrhizal community using a Dendrobium cultivar, D. Stardust 'Firebird', obtained from three nurseries. Additionally, we isolated and tested mycorrhizal fungi in symbiotic culture to assess their role in the seed germination and growth of Dendrobium species. All plants were colonized by mycorrhizal fungi, with a higher colonization rate in mature than in juvenile plants. Molecular identification of mycorrhizal fungi by Sanger and high-throughput sequencing revealed that the cultivar was associated with a phylogenetically diverse group of fungi, including mycorrhizal fungi from Tulasnellaceae, and several wood-decaying fungi. The Tulasnellaceae isolates significantly enhanced the seed germination of three Dendrobium species and increased the survival rate and growth of asymbiotic seedlings of D. moniliforme. This study is the first comprehensive examination of mycorrhizal associations in horticultural orchid hybrids, providing valuable insights for commercial production.

Preliminary Screening on Antibacterial Crude Secondary Metabolites Extracted from Bacterial Symbionts and Identification of Functional Bioactive Compounds by FTIR, HPLC and Gas Chromatography-Mass Spectrometry.

Secondary metabolites, bioactive compounds produced by living organisms, can unveil symbiotic relationships in nature. In this study, soilborne entomopathogenic nematodes associated with symbiotic bacteria (Xenorhabdus stockiae and Photorhabdus luminescens) were extracted from solvent supernatant containing secondary metabolites, demonstrating significant inhibitory effects against E. coli, S. aureus, B. subtilus, P. mirabilis, E. faecalis, and P. stutzeri. The characterization of these secondary metabolites by Fourier transforms infrared spectroscopy revealed amine groups of proteins, hydroxyl and carboxyl groups of polyphenols, hydroxyl groups of polysaccharides, and carboxyl groups of organic acids. Furthermore, the obtained crude extracts were analyzed by high-performance liquid chromatography for the basic identification of potential bioactive peptides. Gas chromatography-mass spectrometry analysis of ethyl acetate extracts from Xenorhabdus stockiae identified major compounds including nonanoic acid derivatives, proline, paromycin, octodecanal derivatives, trioxa-5-aza-1-silabicyclo, 4-octadecenal, methyl ester, oleic acid, and 1,2-benzenedicarboxylicacid. Additional extraction from Photorhabdus luminescens yielded functional compounds such as indole-3-acetic acid, phthalic acid, 1-tetradecanol, nemorosonol, 1-eicosanol, and unsaturated fatty acids. These findings support the potential development of novel natural antimicrobial agents for future pathogen suppression.

A Symbiotic Meal Containing Extruded Sorghum and Probiotic (Bifidobacterium longum) Ameliorated Intestinal Health Markers in Individuals with Chronic Kidney Disease: A Secondary Analysis of a Subsample from a Previous Randomized and Controlled Clinical Trial.

BACKGROUND: Chronic kidney disease increases uremic toxins concentrations, which have been associated with intestinal dysbiosis. Sorghum bicolor L. Moench has dietary fiber and bioactive compounds, while Bifidobacterium longum can promote beneficial health effects. METHODS: It is a controlled, randomized, and single-blind clinical trial. Thirty-nine subjects were randomly separated into two groups: symbiotic group (SG), which received 100 mL of unfermented probiotic milk with Bifidobacterium longum strain and 40 g of extruded sorghum flakes; and the control group (CG), which received 100 mL of pasteurized milk and 40 g of extruded corn flakes for seven weeks. RESULTS: The uremic toxins decreased, and gastrointestinal symptoms improved intragroup in the SG group. The acetic, propionic, and butyric acid production increased intragroup in the SG group. Regarding α-diversity, the Chao1 index was enhanced in the SG intragroup. The KEGG analysis revealed that symbiotic meal increased the intragroup energy and amino sugar metabolism, in addition to enabling essential amino acid production and metabolism, sucrose degradation, and the biosynthesis of ribonucleotide metabolic pathways. CONCLUSIONS: The consumption of symbiotic meal reduced BMI, improved short-chain fatty acid (SCFA) synthesis and gastrointestinal symptoms, increased diversity according to the Chao1 index, and reduced uremic toxins in chronic kidney disease patients.

Legume-grass mixtures improve biological nitrogen fixation and nitrogen transfer by promoting nodulation and altering root conformation in different ecological regions of the Qinghai-Tibet Plateau.

Introduction: Biological nitrogen fixation (BNF) plays a crucial role in nitrogen utilization in agroecosystems. Functional characteristics of plants (grasses vs. legumes) affect BNF. However, little is still known about how ecological zones and cropping patterns affect legume nitrogen fixation. This study's objective was to assess the effects of different cropping systems on aboveground dry matter, interspecific relationships, nodulation characteristics, root conformation, soil physicochemistry, BNF, and nitrogen transfer in three ecological zones and determine the main factors affecting nitrogen derived from the atmosphere (Ndfa) and nitrogen transferred (Ntransfer). Methods: The 15N labeling method was applied. Oats (Avena sativa L.), forage peas (Pisum sativum L.), common vetch (Vicia sativa L.), and fava beans (Vicia faba L.) were grown in monocultures and mixtures (YS: oats and forage peas; YJ: oats and common vetch; YC: oats and fava beans) in three ecological regions (HZ: Huangshui Valley; GN: Sanjiangyuan District; MY: Qilian Mountains Basin) in a split-plot design. Results: The results showed that mixing significantly promoted legume nodulation, optimized the configuration of the root system, increased aboveground dry matter, and enhanced nitrogen fixation in different ecological regions. The percentage of nitrogen derived from the atmosphere (%Ndfa) and percentage of nitrogen transferred (%Ntransfer) of legumes grown with different legume types and in different ecological zones were significantly different, but mixed cropping significantly increased the %Ndfa of the legumes. Factors affecting Ndfa included the cropping pattern, the ecological zone (R), the root nodule number, pH, ammonium-nitrogen, nitrate-nitrogen, microbial nitrogen mass (MBN), plant nitrogen content (N%), and aboveground dry biomass. Factors affecting Ntransfer included R, temperature, altitude, root surface area, nitrogen-fixing enzyme activity, organic matter, total soil nitrogen, MBN, and N%. Discussion: We concluded that mixed cropping is beneficial for BNF and that mixed cropping of legumes is a sustainable and effective forage management practice on the Tibetan Plateau.

The Compact Root Architecture 2 systemic pathway is required for the induction of cytokinins and of the miR399 in Medicago truncatula N-satisfied plants.

Plants use a combination of sophisticated local and systemic pathways to optimize growth depending on heterogeneous nutrient availability in the soil. Legume plants can acquire mineral nitrogen (N) either through their roots or via a symbiotic interaction with N-fixing rhizobia bacteria housed in so-called root nodules. To identify shoot-to-root systemic signals acting in Medicago truncatula plants at N-deficit or N-satiety, plants were grown in a split-root experimental design, in which either high or low N was provided to a half of the root system, allowing the analysis of systemic pathways independently of any local N response. Among the plant hormone families analyzed, the cytokinin trans-Zeatin accumulated in plants at N-satiety. Cytokinin application by petiole feeding led to an inhibition of both root growth and nodulation. In addition, an exhaustive analysis of miRNAs revealed that miR2111 accumulates systemically under N-deficit in both shoots and non-treated distant roots, whereas a miRNA related to inorganic Phosphate (Pi)-acquisition, the miR399, does so in plants grown at N-satiety. These two accumulation patterns are dependent on CRA2 (Compact Root Architecture 2), a receptor required for CEP (C-terminally Encoded Peptide) signaling. Constitutive ectopic expression of the miR399 reduced nodule numbers and root biomass depending on Pi availability, suggesting that the miR399-dependent Pi-acquisition regulatory module controlled by N-availability affects the development of the whole legume plant root system.

Breaking barriers: bacterial-microalgae symbiotic systems as a probiotic delivery system.

The gut microbiota is one of the essential contributors of the pathogenesis and progress of inflammatory bowel disease (IBD). Compared with first-line drug therapy, probiotic supplementation has emerged as a viable and secure therapeutic approach for managing IBD through the regulation of both the immune system and gut microbiota. Nevertheless, the efficacy of oral probiotic supplements is hindered by their susceptibility to the gastrointestinal barrier, leading to diminished bioavailability and restricted intestinal colonization. Here, we developed a bacteria-microalgae symbiosis system (EcN-SP) for targeted intestinal delivery of probiotics and highly effective treatment of colitis. The utilization of mircroalge Spirulina platensis (SP) as a natural carrier for the probiotic Escherichia coli Nissle 1917 (EcN) demonstrated potential benefits in promoting EcN proliferation, facilitating effective intestinal delivery and colonization. The alterations in the binding affinity of EcN-SP within the gastrointestinal environment, coupled with the distinctive structural properties of the SP carrier, served to overcome gastrointestinal barriers, minimizing transgastric EcN loss and enabling sustained intestinal retention and colonization. The oral administration of EcN-SP could effectively treat IBD by reducing the expression of intestinal inflammatory factors, maintaining the intestinal barrier and regulating the balance of gut microbiota. This probiotic delivery approach is inspired by symbiotic interactions found in nature and offers advantages in terms of feasibility, safety, and efficacy, thus holding significant promise for the management of gastrointestinal disorders.

Enhancing Seed Germination of Cremastra appendiculata: Screening and Identification of Four New Symbiotic Fungi in the Psathyrellaceae Family.

Several coprinoid fungi have been identified as promotors of Cremastra appendiculata seed germination, while others appear ineffective. This study aimed to discern which genera within the Psathyrellaceae family exhibit this capability and to identify the most effective coprinoid fungi for the cultivation of C. appendiculata. We collected 21 coprinoid fungi from diverse sources and symbiotically cultured them with C. appendiculata seeds. 9 fungi were found to induce seed germination and support seed development, specifically within the genera Coprinellus, Tulosesus, and Candolleomyces. In contrast, fungi that failed to promote germination predominantly belonged to the genera Coprinopsis and Parasola. Notably, four fungi-Coprinellus xanthothrix, Coprinellus pseudodisseminatus, Psathyrella singeri, and Psathyrella candolleana-were documented for the first time as capable of enhancing C. appendiculata seed germination. Strain 218LXJ-10, identified as Coprinellus radians, demonstrated the most significant effect and has been implemented in large-scale production, underscoring its considerable practical value. These findings contribute vital scientific insights for the conservation and sustainable use of C. appendiculata resources.

Nitrogen deficiency modulates carbon allocation to promote nodule nitrogen fixation capacity in soybean.

Previously, the effect of soil mineral N deficiency on nodule nitrogen fixation capacity (NFC) is unclear. In this study, we found that N deficiency would enhance sucrose allocation to nodules and PEP allocation to bacteroid to promote nodule NFC. Our findings provide new insights into the design of leguminous crops with improved adaptation to fluctuating N levels in the soil.

Elucidating the structure, and composition of bacterial symbionts in the gut regions of wood-feeding termite, Coptotermes formosanus and their functional profile towards lignocellulolytic systems.

The wood-feeding termite, Coptotermes formosanus, presents an efficient lignocellulolytic system, offering a distinctive model for the exploration of host-microbial symbiosis towards lignocellulose degradation. Despite decades of investigation, understanding the diversity, community structure, and functional profiles of bacterial symbionts within specific gut regions, particularly the foregut and midgut of C. formosanus, remains largely elusive. In light of this knowledge gap, our efforts focused on elucidating the diversity, community composition and functions of symbiotic bacteria inhabiting the foregut, midgut, and hindgut of C. formosanus via metagenomics. The termite harbored a diverse community of bacterial symbionts encompassing 352 genera and 26 known phyla, exhibiting an uneven distribution across gut regions. Notably, the hindgut displayed a higher relative abundance of phyla such as Bacteroidetes (56.9%) and Spirochetes (23.3%). In contrast, the foregut and midgut were predominantly occupied by Proteobacteria (28.9%) and Firmicutes (21.2%) after Bacteroidetes. The foregut harbored unique phyla like Candidate phylum_TM6 and Armatimonadetes. At the family level, Porphyromonadaceae (28.1, 40.6, and 53.5% abundance in foregut, midgut, and hindgut, respectively) and Spirochaetaceae (foregut = 9%, midgut = 16%, hindgut = 21.6%) emerged as dominant families in the termite's gut regions. Enriched operational taxonomic units (OTUs) were most abundant in the foregut (28), followed by the hindgut (14), while the midgut exhibited enrichment of only two OTUs. Furthermore, the functional analyses revealed distinct influences of bacterial symbionts on various metabolic pathways, particularly carbohydrate and energy metabolisms of the host. Overall, these results underscore significant variations in the structure of the bacterial community among different gut regions of C. formosanus, suggesting unique functional roles of specific bacteria, thereby inspiring further investigations to resolve the crosstalk between host and microbiomes in individual gut-regions of the termite.

Metabolic relationships between marine red algae and algae-associated bacteria.

Mutualistic interactions between marine phototrophs and associated bacteria are an important strategy for their successful survival in the ocean, but little is known about their metabolic relationships. Here, bacterial communities in the algal sphere (AS) and bulk solution (BS) of nine marine red algal cultures were analyzed, and Roseibium and Phycisphaera were identified significantly more abundantly in AS than in BS. The metabolic features of Roseibium RMAR6-6 (isolated and genome-sequenced), Phycisphaera MAG 12 (obtained by metagenomic sequencing), and a marine red alga, Porphyridium purpureum CCMP1328 (from GenBank), were analyzed bioinformatically. RMAR6-6 has the genetic capability to fix nitrogen and produce B vitamins (B1, B2, B5, B6, B9, and B12), bacterioferritin, dimethylsulfoniopropionate (DMSP), and phenylacetate that may enhance algal growth, whereas MAG 12 may have a limited metabolic capability, not producing vitamins B9 and B12, DMSP, phenylacetate, and siderophores, but with the ability to produce bacitracin, possibly modulating algal microbiome. P. purpureum CCMP1328 lacks the genetic capability to fix nitrogen and produce vitamin B12, DMSP, phenylacetate, and siderophore. It was shown that the nitrogen-fixing ability of RMAR6-6 promoted the growth of P. purpureum, and DMSP reduced the oxidative stress of P. purpureum. The metabolic interactions between strain RMAR6-6 and P. purpureum CCMP1328 were also investigated by the transcriptomic analyses of their monoculture and co-culture. Taken together, potential metabolic relationships between Roseibium and P. purpureum were proposed. This study provides a better understanding of the metabolic relationships between marine algae and algae-associated bacteria for successful growth. Supplementary Information: The online version contains supplementary material available at 10.1007/s42995-024-00227-z.

Phylogenomics corroborates morphology: New discussions on the systematics of Trichostomatia (Ciliophora, Litostomatea).

The subclass Trichostomatia (Ciliophora, Litostomatea) constitutes a well-supported monophyletic group, which includes ciliates exclusively found as symbionts of vertebrates, primarily herbivorous mammals. Recent molecular analyses reinforce the subclass monophyly, though almost all orders, suborders, families, and genera are found to be non-monophyletic. Here, we reconstructed the evolutionary history of the subclass Trichostomatia using a phylogenomic approach and discussed some systematic inconsistencies. We propose a new Ophryoscolecidae genus, Dagostonium, to include Diplodinium polygonale. Monoposthium cynodontum is transferred to the genus Cycloposthium.

Cutaneous shedding in amphibians causes shifts in bacterial microbiomes.

Considerable research has focused on microbes on amphibian skin, as they act as the first line of defense against invading pathogens. This effort has generated substantial data on patterns across species, space, time, and ontogeny, alongside a growing list of beneficial antifungal symbionts. Though there is evidence of stability in amphibian skin microbial communities, there is also an indication that regular skin shedding reduces cultivable bacteria, with regrowth and recolonization in the period between sheds. This suggests that skin communities are in constant flux, and we lack an understanding of how the membership and structure of those communities are affected by shedding events. In this study, we conducted experiments on cane toads (Rhinella marina) to investigate the influence of shedding on skin microbiomes. We first used quantitative PCR to verify a positive correlation between bacterial loads and time in the days after shedding. We then resampled individuals over time to describe changes in community composition in the 38 h after shedding using amplicon sequencing. Similar to trends of bacterial loads, we found increases in alpha diversity over time after shedding, suggesting that shedding reduces bacterial diversity as it knocks down bacterial loads. During the 38-h period, community structure became similar to pre-shed communities in some individuals, but there was no consistent pattern in structural changes among individuals. In light of the amphibian chytridiomycosis pandemic, understanding how physiological events such as skin shedding affect beneficial bacteria and communities on amphibians would provide important insight into amphibian ecology.

Untangling the interplay of dissolved organic matters variation with microbial symbiotic network in sludge anaerobic fermentation triggered by various pretreatments.

Various pretreatments are commonly adopted to facilitate dissolved organic matter (DOM) release from waste activated sludge (WAS) for high-valued volatile fatty acids (VFAs) promotion, while the interplay impact of DOM dynamics transformation on microbial population and metabolic function traits is poorly understood. This work constructed "DOM-microorganisms-metabolism-VFAs" symbiotic ecologic networks to disclose how DOM dynamics variation intricately interacts with bacterial community networks, assembly processes, and microbial traits during WAS fermentation. The distribution of DOM was altered by different pretreatments, triggering the release of easily biodegradable compounds (O/C ratio > 0.3) and protein-like substance. This alteration greatly improved the substrates biodegradability (higher biological index) and upregulated microbial metabolism capacity (e.g., hydrolysis and fatty acid synthesis). In turn, microbial activity modifications augment substance metabolism level and expedite the conversion of highly reactive compounds (proteins-like DOM) to VFAs, leading to 1.6-4.2 fold rise in VFAs generation. Strong correlations were found between proteins-like DOM and topological properties of DOM-bacteria associations, suggesting that high DOM availability leads to more intricate ecological networks. A change in the way communities assemble, shifting from stronger uniform selection in pH10 and USp reactors to increased randomness in heat reactor, was linked to DOM composition alterations. The ecologic networks further revealed metabolic synergy between hydrolytic-acidogenic bacteria (e.g., Bacteroidota and Firmicutes) and biodegradable DOM (e.g., proteins and amino sugars) leading to higher VFAs generation. This study provides a deeper knowledge of the inherent connections between DOM and microbial traits for efficient VFAs biosynthesis during WAS anaerobic fermentation, offering valuable insights for effective WAS pretreatment strategies.

Managing Super Pests: Interplay between Pathogens and Symbionts Informs Biocontrol of Whiteflies.

Bemisia tabaci is distributed globally and incurs considerable economic and ecological costs as an agricultural pest and viral vector. The entomopathogenic fungus Metarhizium anisopliae has been known for its insecticidal activity, but its impacts on whiteflies are understudied. We investigated how infection with the semi-persistently transmitted Cucurbit chlorotic yellows virus (CCYV) affects whitefly susceptibility to M. anisopliae exposure. We discovered that viruliferous whiteflies exhibited increased mortality when fungus infection was present compared to non-viruliferous insects. High throughput 16S rRNA sequencing also revealed significant alterations of the whitefly bacterial microbiome diversity and structure due to both CCYV and fungal presence. Specifically, the obligate symbiont Portiera decreased in relative abundance in viruliferous whiteflies exposed to M. anisopliae. Facultative Hamiltonella and Rickettsia symbionts exhibited variability across groups but dominated in fungus-treated non-viruliferous whiteflies. Our results illuminate triangular interplay between pest insects, their pathogens, and symbionts-dynamics which can inform integrated management strategies leveraging biopesticides This work underscores the promise of M. anisopliae for sustainable whitefly control while laying the groundwork for elucidating mechanisms behind microbe-mediated shifts in vector competence.