Adhesion of Klebsiella oxytoca to bladder or lung epithelial cells is promoted by the presence of other opportunistic pathogens.

The intestinal and respiratory tracts of healthy individuals serve as habitats for a diverse array of microorganisms, among which Klebsiella oxytoca holds significance as a causative agent in numerous community- and hospital-acquired infections, often manifesting in polymicrobial contexts. In specific circumstances, K. oxytoca, alongside other constituents of the gut microbiota, undergoes translocation to distinct physiological niches. In these new environments, it engages in close interactions with other microbial community members. As this interaction may progress to co-infection where the virulence of involved pathogens may be promoted and enhance disease severity, we investigated how K. oxytoca affects the adhesion of commonly co-isolated bacteria and vice versa during co-incubation of different biotic and abiotic surfaces. Co-incubation was beneficial for the adhesion of at least one of the two co-cultured strains. K. oxytoca enhanced the adhesion of other enterobacteria strains to polystyrene and adhered more efficiently to bladder or lung epithelial cell lines in the presence of most enterobacteria strains and S. aureus. This effect was accompanied by bacterial coaggregation mediated by carbohydrate-protein interactions occurring between bacteria. These interactions occur only in sessile, but not planktonic populations, and depend on the features of the surface. The data are of particular importance for the risk assessment of the urinary and respiratory tract infections caused by K. oxytoca, including those device-associated. In this paper, we present the first report on K. oxytoca ability to acquire increased adhesive capacities on epithelial cells through interactions with common causal agents of urinary and respiratory tract infections.

Unraveling the ecological mechanisms of Aluminum on microbial community succession in epiphytic biofilms on Vallisneria natans leaves: Novel insights from microbial interactions.

The extensive use of aluminum (Al) poses an escalating ecological risk to aquatic ecosystems. The epiphytic biofilm on submerged plant leaves plays a crucial role in the regulation nutrient cycling and energy flow within aquatic environments. Here, we conducted a mesocosm experiment aimed at elucidating the impact of different Al concentrations (0, 0.6, 1.2, 2.0 mg/L) on microbial communities in epiphytic biofilms on Vallisneria natans. At 1.2 mg/L, the highest biofilms thickness (101.94 µm) was observed. Al treatment at 2.0 mg/L significantly reduced bacterial diversity, while micro-eukaryotic diversity increased. Pseudomonadota and Bacteroidota decreased, whereas Cyanobacteriota increased at 1.2 mg/L and 2.0 mg/L. At 1.2 and 2.0 mg/L. Furthermore, Al at concentrations of 1.2 and 2.0 mg/L enhanced the bacterial network complexity, while micro-eukaryotic networks showed reduced complexity. An increase in positive correlations among microbial co-occurrence patterns from 49.51% (CK) to 57.05% (2.0 mg/L) was indicative of augmented microbial cooperation under Al stress. The shift in keystone taxa with increasing Al concentration pointed to alterations in the functional dynamics of microbial communities. Additionally, Al treatments induced antioxidant responses in V. natans, elevating leaf reactive oxygen species (ROS) content. This study highlights the critical need to control appropriate concentration Al concentrations to preserve microbial diversity, sustain ecological functions, and enhance lake remediation in aquatic ecosystems.

Bioponic systems with biochar: Insights into nutrient recovery, heavy metal reduction, and microbial interactions in digestate-based bioponics.

Bioponics is a nutrient-recovery technology that transforms nutrient-rich organic waste into plant biomass/bioproducts. Integrating biochar with digestate from anaerobic wastewater treatment process can improve resource recovery while mitigating heavy metal contamination. The overarching goal of this study was to investigate the application of biochar in digestate-based bioponics, focusing on its efficacy in nutrient recovery and heavy metal removal, while also exploring the microbial community dynamics. In this study, biochar was applied at 50 % w/w with 500 g dry weight of digestate during two 28-day crop cycles (uncontrolled pH and pH 5.5) using white stem pak choi (Brassica rapa var. chinensis) as a model crop. The results showed that the digestate provided sufficient phosphorus and nitrogen, supporting plant growth. Biochar amendment improved plant yield and phosphate solubilization and reduced nitrogen loss, especially at the pH 5.5. Furthermore, biochar reduced the heavy metal accumulation in plants, while concentrating these metals in the residual sludge. However, owing to potential non-carcinogenic and carcinogenic health risks, it is still not recommended to directly consume plants cultivated in digestate-based bioponic systems. Additionally, biochar amendment exhibited pronounced impact on the microbial community, promoting microbes responsible for nutrient solubilization and cycling (e.g., Tetrasphaera, Herpetosiphon, Hyphomicrobium, and Pseudorhodoplanes) and heavy metal stabilization (e.g., Leptolinea, Fonticella, Romboutsia, and Desulfurispora) in both the residual sludge and plants. Overall, the addition of biochar enhanced the microbial community and facilitated the metal stabilization and the cycling of nutrients within both residual sludge and root systems, thereby improving the overall efficiency of the bioponics.

Microbial and metabolic profiles unveil mutualistic microbe-microbe interaction in obesity-related colorectal cancer.

Obesity is a risk factor for colorectal cancer (CRC), and the involvement of gut microbiota in the pathogenesis of obesity and CRC is widely recognized. However, the landscape of fecal microbiome and metabolome distinguishing patients with obesity-related CRC from obesity remains unknown. Here, we utilize metagenomic sequencing and metabolomics from 522 patients with CRC and healthy controls to identify the characteristics of obese CRC. Our integrated analysis reveals that obesity-related CRC is characterized by elevated Peptostreptococcus stomatis, dysregulated fatty acids and phospholipids, and altered Kyoto Encyclopedia of Genes and Genomes pathways involving glycerophospholipid metabolism and lipopolysaccharide synthesis. Correlation analysis unveils microbial interactions in obesity, where the probiotic Faecalibacterium prausnitzii and the tumor-promoting species P. stomatis may engage in cross-feeding, thereby promoting tumorigenesis. In vitro experiments affirm enhanced growth under cross-feeding conditions. The mutualistic microbe-microbe interaction may contribute to the association between obesity and elevated CRC risk. Additionally, diagnostic models incorporating BMI-specific microbial biomarkers display promise for precise CRC screening.

Autolysis of Pseudomonas aeruginosa Quorum-Sensing Mutant Is Suppressed by Staphylococcus aureus through Iron-Dependent Metabolism.

Microorganisms usually coexist as a multifaceted polymicrobial community in the natural habitats and at mucosal sites of the human body. Two opportunistic human pathogens, Pseudomonas aeruginosa and Staphylococcus aureus commonly coexist in the bacterial infections for hospitalized and/or immunocompromised patients. Here, we observed that autolysis of the P. aeruginosa quorum-sensing (QS) mutant (lasRmvfR) was suppressed by the presence of the S. aureus cells in vitro. The QS mutant still displayed killing against S. aureus cells, suggesting the link between the S. aureus-killing activity and the autolysis suppression. Independent screens of the P. aeruginosa transposon mutants defective in the S. aureus-killing and the S. aureus transposon mutants devoid of the autolysis suppression revealed the genetic link between both phenotypes, suggesting that the iron-dependent metabolism involving S. aureus exoproteins might be central to both phenotypes. The autolysis was suppressed by iron treatment as well. These results suggest that the interaction between P. aeruginosa and S. aureus might be governed by mechanisms that necessitate the QS circuitry as well as the metabolism involving the extracellular iron resources during the polymicrobial infections in the human airway.

Microplastics shape microbial interactions and affect the dissemination of antibiotic resistance genes in different full-scale wastewater treatment plants.

Wastewater treatment plants (WWTPs) pose a potential threat to the environment because of the accumulation of antibiotic resistance genes (ARGs) and microplastics (MPs). However, the interactions between ARGs and MPs, which have both indirect and direct effects on ARG dissemination in WWTPs, remain unclear. In this study, spatiotemporal variations in different types of MPs, ten ARGs (sul1, sul2, tetA, tetO, tetM, tetX, tetW, qnrS, ermB, and ermC), class 1 integron integrase (intI1) and transposon Tn916/1545 in three typical WWTPs were characterized. Sul1, tetO, and sul2 were the predominant ARGs in the targeted WWTPs, whereas the intI1 and transposon Tn916/1545 were positively correlated with most of the targeted ARGs. Saccharimonadales (4.15 %), Trichococcus (2.60 %), Nitrospira (1.96 %), Candidatus amarolinea (1.79 %), and SC-I-84 (belonging to phylum Proteobacteria) (1.78 %) were the dominant genera. Network and redundancy analyses showed that Trichococcus, Faecalibacterium, Arcobacter, and Prevotella copri were potential hosts of ARGs, whereas Candidatus campbellbacteria and Candidatus kaiserbacteria were negatively correlated with ARGs. The potential hosts of ARGs had a strong positive correlation with polyethylene terephthalate, silicone resin, and fluor rubber and a negative correlation with polyurethane. Candidatus campbellbacteria and Candidatus kaiserbacteria were positively correlated with polyurethane, whereas potential hosts of ARGs were positively correlated with polypropylene and fluor rubber. Structural equation modeling highlighted that intI1, transposon Tn916/1545 and microbial communities, particularly microbial diversity, dominated the dissemination of ARGs, whereas MPs had a significant positive correlation with microbial abundance. Our study deepens the understanding of the relationships between ARGs and MPs in WWTPs, which will be helpful in designing strategies for inhibiting ARG hosts in WWTPs.

Multi-omics analysis reveals the microbial interactions of S. cerevisiae and L. plantarum on Suanyu, Chinese traditional fermented fish.

S. cerevisiae and L. plantarum play important roles in Suanyu fermentation. This study investigated the interaction between S. cerevisiae and L. plantarum during fermentation and its impact on metabolic pathways. Co-culturing S. cerevisiae and L. plantarum increased pH to 5.72, reduced TVB-N to 9.47 mg/mL, and achieved high utilization rates of sugars (98.9%) and proteins (73.7%). During microbial interactions, S. cerevisiae and L. plantarum produced antibiotics, including phenyllactate and Gentamicin C1a, inhibiting the growth of each other. S. cerevisiae used S-adenosyl-l-methionine to counteract acid production of L. plantarum, establishing dominance in Suanyu fermentation. Microbial interactions influenced carbohydrate and energy metabolism pathways, such as nicotinate and nicotinamide metabolism and purine metabolism. S. cerevisiae significantly impacted gene expression in protein synthesis and cell growth pathways, including ribosome, SNARE interactions, basal transcription factors, and MAPK signaling. These findings offer insights into microbial interactions and metabolic processes during Suanyu fermentation.

A meta-analysis of tissue microbial biomarkers for recurrence and metastasis in multiple cancer types.

Background. Local recurrence and distant metastasis are the main causes of death in patients with cancer. Only considering species abundance changes when identifying markers of recurrence and metastasis in patients hinders finding solutions.Hypothesis. Consideration of microbial abundance changes and microbial interactions facilitates the identification of microbial markers of tumour recurrence and metastasis.Aim. This study aims to simultaneously consider microbial abundance changes and microbial interactions to identify microbial markers of recurrence and metastasis in multiple cancer types.Method. One thousand one hundred and six non-RM (patients without recurrence and metastasis within 3 years after initial surgery) tissue samples and 912 RM (patients with recurrence or metastasis within 3 years after initial surgery) tissue samples representing 11 cancer types were collected from The Cancer Genome Atlas (TCGA).Results. Tumour tissue bacterial composition differed significantly among 11 cancers. Among them, the tissue microbiome of four cancers, head and neck squamous cell carcinoma (HNSC), lung squamous cell carcinoma (LUSC), stomach adenocarcinoma (STAD) and uterine corpus endometrial carcinoma (UCEC), showed relatively good performance in predicting recurrence and metastasis in patients, with areas under the receiver operating characteristic curve (AUCs) of 0.78, 0.74, 0.91 and 0.93, respectively. Considering both species abundance changes and microbial interactions for the four cancers, a combination of nine genera (Niastella, Schlesneria, Thioalkalivibrio, Phaeobacter, Sphaerotilus, Thiomonas, Lawsonia, Actinobacillus and Spiroplasma) performed best in predicting patient survival.Conclusion. Taken together, our results imply that comprehensive consideration of microbial abundance changes and microbial interactions is helpful for mining bacterial markers that carry prognostic information.

Spontaneous body wall contractions stabilize the fluid microenvironment that shapes host-microbe associations.

The freshwater polyp Hydra is a popular biological model system; however, we still do not understand one of its most salient behaviors, the generation of spontaneous body wall contractions. Here, by applying experimental fluid dynamics analysis and mathematical modeling, we provide functional evidence that spontaneous contractions of body walls enhance the transport of chemical compounds from and to the tissue surface where symbiotic bacteria reside. Experimentally, a reduction in the frequency of spontaneous body wall contractions is associated with a changed composition of the colonizing microbiota. Together, our findings suggest that spontaneous body wall contractions create an important fluid transport mechanism that (1) may shape and stabilize specific host-microbe associations and (2) create fluid microhabitats that may modulate the spatial distribution of the colonizing microbes. This mechanism may be more broadly applicable to animal-microbe interactions since research has shown that rhythmic spontaneous contractions in the gastrointestinal tracts are essential for maintaining normal microbiota.

LRBmat: A novel gut microbial interaction and individual heterogeneity inference method for colorectal cancer.

The gut microbial community has been shown to play a significant role in various diseases, including colorectal cancer (CRC), which is a major public health concern worldwide. The accurate diagnosis and etiological analysis of CRC are crucial issues. Numerous methods have utilized gut microbiota to address these challenges; however, few have considered the complex interactions and individual heterogeneity of the gut microbiota, which are important issues in genetics and intestinal microbiology, particularly in high-dimensional cases. This paper presents a novel method called Binary matrix based on Logistic Regression (LRBmat) to address these concerns. The binary matrix in LRBmat can directly mitigate or eliminate the influence of heterogeneity, while also capturing information on gut microbial interactions with any order. LRBmat is highly adaptable and can be combined with any machine learning method to enhance its capabilities. The proposed method was evaluated using real CRC data and demonstrated superior classification performance compared to state-of-the-art methods. Furthermore, the association rules extracted from the binary matrix of the real data align well with biological properties and existing literature, thereby aiding in the etiological analysis of CRC.

Pulcherriminic acid modulates iron availability and protects against oxidative stress during microbial interactions.

Siderophores are soluble or membrane-embedded molecules that bind the oxidized form of iron, Fe(III), and play roles in iron acquisition by microorganisms. Fe(III)-bound siderophores bind to specific receptors that allow microbes to acquire iron. However, certain soil microbes release a compound (pulcherriminic acid, PA) that, upon binding to Fe(III), forms a precipitate (pulcherrimin) that apparently functions by reducing iron availability rather than contributing to iron acquisition. Here, we use Bacillus subtilis (PA producer) and Pseudomonas protegens as a competition model to show that PA is involved in a peculiar iron-managing system. The presence of the competitor induces PA production, leading to precipitation of Fe(III) as pulcherrimin, which prevents oxidative stress in B. subtilis by restricting the Fenton reaction and deleterious ROS formation. In addition, B. subtilis uses its known siderophore bacillibactin to retrieve Fe(III) from pulcherrimin. Our findings indicate that PA plays multiple roles by modulating iron availability and conferring protection against oxidative stress during inter-species competition.

Aspergillus co-cultures: A recent insight into their secondary metabolites and microbial interactions.

There is an urgent need for novel antibiotics to combat emerging resistant microbial strains. One of the most pressing resources is Aspergillus microbial cocultures. The genome of Aspergillus species comprises a far larger number of novel gene clusters than previously expected, and novel strategies and approaches are essential to exploit this potential source of new drugs and pharmacological agents. This is the first review consulting recent developments and chemical diversity of Aspergillus cocultures and highlighting its untapped richness. The analyzed data revealed that cocultivation of several Aspergillus species with other microorganisms, including bacteria, plants, and fungi, is a source of novel bioactive natural products. Various vital chemical skeleton leads were newly produced or augmented in Aspergillus cocultures, among which were taxol, cytochalasans, notamides, pentapeptides, silibinin, and allianthrones. The possibility of mycotoxin production or complete elimination in cocultivations was detected, which pave the way for better decontamination strategies. Most cocultures revealed a remarkable improvement in their antimicrobial or cytotoxic behavior due to their produced chemical patterns; for instance, weldone and asperterrin whose antitumor and antibacterial activities, respectively, were superior. Microbial cocultivation elicited the upregulation or production of specific metabolites whose importance and significance are yet to be revealed. With more than 155 compounds isolated from Aspergillus cocultures in the last 10 years, showing overproduction, reduction, or complete suppression under the optimized coculture circumstances, this study filled a gap for medicinal chemists searching for new lead sources or bioactive molecules as anticancer agents or antimicrobials.

Electric-Inducive Microbial Interactions in a Thermophilic Anaerobic Digester Revealed by High-Throughput Sequencing of Micron-Scale Single Flocs.

Although conductive materials have been shown to improve efficiency in anaerobic digestion (AD) by modifying microbial interactions, the interacting network under thermophilic conditions has not been examined. To identify the true taxon-taxon associations within thermophilic anaerobic digestion (TAD) microbiome and reveal the influence of carbon cloth (CC) addition, we sampled micron-scale single flocs (40-70 µm) randomly isolated from lab-scale thermophilic digesters. Results revealed that CC addition not only significantly boosted methane yield by 25.3% but also increased the spatial heterogeneity of the community in the sludge medium. After CC addition, an evident translocation of Pseudomonas from the medium to the biofilm was observed, showing their remarkable capacity for biofilm formation. Additionally, Clostridium and Thermotogaceae tightly aggregated and steadily co-occurred in the medium and biofilm of the TAD microbiome, which might be associated with their unique extracellular sugar metabolizing style. Finally, CC induced syntrophic interaction between Syntrophomonas and denitrifiers of Rhodocyclaceae. The upregulated respiration-associated electron transferring genes (Cyst-c, complex III) on the cellular membranes of these collaborating partners indicated a potential coupling of the denitrification pathway with syntrophic acetate oxidation via direct interspecies electron transfer (DIET). These findings provide an insight into how conductive materials promote thermophilic digestion performance and open the path for improved community monitoring of biotreatment systems.

Effector-Dependent and -Independent Molecular Mechanisms of Soybean-Microbe Interaction.

Soybean is a pivotal staple crop worldwide, supplying the main food and feed plant proteins in some countries. In addition to interacting with mutualistic microbes, soybean also needs to protect itself against pathogens. However, to grow inside plant tissues, plant defense mechanisms ranging from passive barriers to induced defense reactions have to be overcome. Pathogenic but also symbiotic micro-organisms effectors can be delivered into the host cell by secretion systems and can interfere with the immunity system and disrupt cellular processes. This review summarizes the latest advances in our understanding of the interaction between secreted effectors and soybean feedback mechanism and uncovers the conserved and special signaling pathway induced by pathogenic soybean cyst nematode, Pseudomonas, Xanthomonas as well as by symbiotic rhizobium.

New insights into microbial interactions and putative competitive mechanisms during the hydrogen production from tequila vinasses.

This study aimed to characterize the prokaryotic community and putative microbial interactions involved in hydrogen (H2) production during the dark fermentation (DF) process, applying principal components analysis (PCA) to correlate changes in operational, physicochemical, and biological variables. For this purpose, a continuous stirred-tank reactor-type digester fed with tequila vinasses was operated at 24, 18, and 12 h of hydraulic retention times (HRTs) to apply organic loading rates of 20, 36, and 54 g-COD L-1 d-1, corresponding to stages I, II, and III, respectively. Results indicated high population dynamics for Archaea during the DF process toward a decrease in total sequences from 6299 to 99. Concerning the Bacteria community, lactic acid bacteria (LAB) were dominant reaching a relative abundance of 57.67%, while dominant H2-producing bacteria (HPB) decreased from 25.76% to 21.06% during stage III. Putative competitive exclusion mechanisms such as competition for substrates, bacteriocins production, and micronutrient depletion carried out by Archaea and non-H2-producing bacteria (non-HPB), especially LAB, could negatively impact the dominance of HPB such as Ethanoligenens harbinense and Clostridium tyrobutyricum. As a consequence, low maximal volumetric H2 production rate (672 mL-H2 L-1 d-1) and yield (3.88 mol-H2 assimilated sugars-1) were obtained. The global scenario obtained by PCA correlations suggested that C. tyrobutyricum positively impacted H2 molar yield through butyrate fermentation using the butyryl-CoA:acetate CoA transferase pathway, while the most abundant HPB E. harbinense decreased its relative abundance at the shortest HRT toward the dominance of non-HPB. This study provides new insights into the microbial interactions and helps to better understand the DF performance for H2 production using tequila vinasses as substrate. KEY POINTS: • E. harbinense and C. tyrobutyricum were responsible for H2 production. • Clostridiales used acetate and butyrate fermentations for H2 production. • LAB won the competition for sugars against Clostridiales during DF. • Putative bacteriocins production and micronutrients depletion could favor LAB.

Host-mycobiome metabolic interactions in health and disease.

Fungal communities (mycobiome) have an important role in sustaining the resilience of complex microbial communities and maintenance of homeostasis. The mycobiome remains relatively unexplored compared to the bacteriome despite increasing evidence highlighting their contribution to host-microbiome interactions in health and disease. Despite being a small proportion of the total species, fungi constitute a large proportion of the biomass within the human microbiome and thus serve as a potential target for metabolic reprogramming in pathogenesis and disease mechanism. Metabolites produced by fungi shape host niches, induce immune tolerance and changes in their levels prelude changes associated with metabolic diseases and cancer. Given the complexity of microbial interactions, studying the metabolic interplay of the mycobiome with both host and microbiome is a demanding but crucial task. However, genome-scale modelling and synthetic biology can provide an integrative platform that allows elucidation of the multifaceted interactions between mycobiome, microbiome and host. The inferences gained from understanding mycobiome interplay with other organisms can delineate the key role of the mycobiome in pathophysiology and reveal its role in human disease.

Small molecule modulation of microbiota: a systems pharmacology perspective.

BACKGROUND: Microbes are associated with many human diseases and influence drug efficacy. Small-molecule drugs may revolutionize biomedicine by fine-tuning the microbiota on the basis of individual patient microbiome signatures. However, emerging endeavors in small-molecule microbiome drug discovery continue to follow a conventional "one-drug-one-target-one-disease" process. A systematic pharmacology approach that would suppress multiple interacting pathogenic species in the microbiome, could offer an attractive alternative solution. RESULTS: We construct a disease-centric signed microbe-microbe interaction network using curated microbe metabolite information and their effects on host. We develop a Signed Random Walk with Restart algorithm for the accurate prediction of effect of microbes on human health and diseases. With a survey on the druggable and evolutionary space of microbe proteins, we find that 8-10% of them can be targeted by existing drugs or drug-like chemicals and that 25% of them have homologs to human proteins. We demonstrate that drugs for diabetes can be the lead compounds for development of microbiota-targeted therapeutics. We further show that the potential drug targets that specifically exist in pathogenic microbes are periplasmic and cellular outer membrane proteins. CONCLUSION: The systematic studies of the polypharmacological landscape of the microbiome network may open a new avenue for the small-molecule drug discovery of the microbiome. We believe that the application of systematic method on the polypharmacological investigation could lead to the discovery of novel drug therapies.

Interbacterial Antagonism Mediated by a Released Polysaccharide.

Pseudomonas aeruginosa and Staphylococcus aureus are two common pathogens causing chronic infections in the lungs of people with cystic fibrosis (CF) and in wounds, suggesting that these two organisms coexist in vivo. However, P. aeruginosa utilizes various mechanisms to antagonize S. aureus when these organisms are grown together in vitro. Here, we suggest a novel role for Psl in antagonizing S. aureus growth. Psl is an exopolysaccharide that exists in both cell-associated and cell-free forms and is important for biofilm formation in P. aeruginosa. When grown in planktonic coculture with a P. aeruginosa psl mutant, S. aureus had increased survival compared to when it was grown with wild-type P. aeruginosa. We found that cell-free Psl was critical for the killing, as purified cell-free Psl was sufficient to kill S. aureus. Transmission electron microscopy of S. aureus treated with Psl revealed disrupted cell envelopes, suggesting that Psl causes S. aureus cell lysis. This was independent of known mechanisms used by P. aeruginosa to antagonize S. aureus. Cell-free Psl could also promote S. aureus killing during growth in in vivo-like conditions. We also found that Psl production in P. aeruginosa CF clinical isolates positively correlated with the ability to kill S. aureus. This could be a result of P. aeruginosa coevolution with S. aureus in CF lungs. In conclusion, this study defines a novel role for P. aeruginosa Psl in killing S. aureus, potentially impacting the coexistence of these two opportunistic pathogens in vivo. IMPORTANCE Pseudomonas aeruginosa and Staphylococcus aureus are two important opportunistic human pathogens commonly coisolated from clinical samples. However, P. aeruginosa can utilize various mechanisms to antagonize S. aureus in vitro. Here, we investigated the interactions between these two organisms and report a novel role for P. aeruginosa exopolysaccharide Psl in killing S. aureus. We found that cell-free Psl could kill S. aureus in vitro, possibly by inducing cell lysis. This was also observed in conditions reflective of in vivo scenarios. In accord with this, Psl production in P. aeruginosa clinical isolates positively correlated with their ability to kill S. aureus. Together, our data suggest a role for Psl in affecting the coexistence of P. aeruginosa and S. aureus in vivo.

Microbial interactions enhanced environmental fitness and expanded ecological niches under dibutyl phthalate and cadmium co-contamination.

Co-contamination of organic pollutants and heavy metals is universal in the natural environment. Dibutyl phthalate (DBP), a typical plasticizer, frequently coexists with cadmium (Cd) in nature. However, little attention has been given to the impacts of co-contamination by DBP and Cd on microbial communities or the responses of microbes. To address this, a microcosm experiment was conducted by supplying the exogenous DBP-degrading bacterium Glutamicibacter nicotianae ZM05 to investigate the interplay among DBP-Cd co-contamination, the exogenous DBP-degrading bacterium G. nicotianae ZM05, and indigenous microorganisms. To adapt to co-contamination stress, microbial communities adjust their diversity, interactions, and functions. The stability of the microbial community decreased under co-contamination, as evidenced by lower diversity, simpler network, and fewer ecological niches. Microbial interactions were strengthened, as evidenced by enriched pathways related to microbial communications. Meanwhile, interactions between microorganisms enhanced the environmental fitness of the exogenous DBP-degrading bacterium ZM05. Based on co-occurrence network prediction and coculture experiments, metabolic interactions between the non-DBP-degrading bacterium Cupriavidus metallidurans ZM16 and ZM05 were proven. Strain ZM16 utilized protocatechuic acid, a DBP downstream metabolite, to relieve acid inhibition and adsorbed Cd to relieve toxic stress. These findings help to explain the responses of bacterial and fungal communities to DBP-Cd co-contamination and provide new insights for the construction of degrading consortia for bioremediation.

Hydra and the hair follicle - An unconventional comparative biology approach to exploring the human holobiont.

The microbiome of human hair follicles (HFs) has emerged as an important player in different HF and skin pathologies, yet awaits in-depth exploration. This raises questions regarding the tightly linked interactions between host environment, nutrient dependency of host-associated microbes, microbial metabolism, microbe-microbe interactions and host immunity. The use of simple model systems facilitates addressing generally important questions and testing overarching, therapeutically relevant principles that likely transcend obvious interspecies differences. Here, we evaluate the potential of the freshwater polyp Hydra, to dissect fundamental principles of microbiome regulation by the host, that is the human HF. In particular, we focus on therapeutically targetable host-microbiome interactions, such as nutrient dependency, microbial interactions and host defence. Offering a new lens into the study of HF - microbiota interactions, we argue that general principles of how Hydra manages its microbiota can inform the development of novel, microbiome-targeting therapeutic interventions in human skin disease.