Microbial Ecology最新文献

Dynamic social interactions within bacterial biofilms drive distinct spatial organisation and transcriptional responses. Here, we combine fluorescence in situ hybridisation (FISH), confocal laser scanning microscopy (CLSM), and RNA sequencing (RNA-Seq) to investigate a model three-species biofilm community derived from a dairy pasteuriser, comprising Stenotrophomonas rhizophila, Microbacterium lacticum, and Bacillus licheniformis. CLSM revealed species-specific biovolume dynamics and stratified 3D structures over 24 h, with S. rhizophila as the dominant species and M. lacticum exhibiting the lowest abundance yet playing an essential role as the initial coloniser. Spatial patterns reflected known pairwise interactions - commensalism, exploitation, and neutral interaction. Transcriptomic profiling of S. rhizophila revealed extensive gene expression changes in dual-species biofilms with M. lacticum, including upregulation of genes related to flagellar motility, nutrient acquisition, energy metabolism, and TonB-dependent transport. In contrast, co-culture with B. licheniformis induced minimal transcriptional changes in S. rhizophila, consistent with a neutral interaction among the two. Our findings demonstrate how interspecies interactions govern both spatial topology and functional specialisation in mixed-species biofilms which is of relevance to microbial ecology, industrial biofilm control, and the targeting of keystone biofilm species.

As global environmental challenges intensify, enhancing forest health and soil quality has emerged as a crucial area of research. Understanding and application of beneficial bacteria in forestry industry is urgently needed as an environmentally friendly and sustainable approach. Although thousands of patents have been registered for microbial application in agriculture and forestry, the mechanisms and application of beneficial bacteria on the soil nutrient availability have not been well summarized. This review investigated the role of beneficial bacteria in tree growth, particularly their contributions to soil nutrient availability in forest trees. We summarized that beneficial bacteria significantly enhance the availability of essential elements such as nitrogen, phosphorus, potassium, and iron by promoting nutrient cycling and transformation within the soil. This process supports tree growth and improves soil quality. Additionally, beneficial bacteria facilitate plant growth by synthesizing plant hormones and inducing resistance to biotic and abiotic stresses. This review concludes by discussing practical implications of beneficial bacterial colonization and application for enhancing soil nutrient levels, along with potential future research directions. We have enriched the theoretical framework of forest-associated bacteria and provided a scientific basis that can inform forest management and ecological restoration.

Quorum sensing (QS) is a cell-cell communication mechanism mediated by secreted hormone-like signaling molecules that operates in both Gram-positive and Gram-negative bacteria, driving coordinated alterations in gene expression once a critical cell density is reached. In these prokaryotic systems, bacteria produce, release, detect, and respond to small autoinducers, such as acyl-homoserine lactones in Gram-negative bacteria, oligopeptides in Gram-positive bacteria, and the universal autoinducer-2, to regulate community behaviors including biofilm formation, virulence factor production, and stress adaptation. The concept of QS in eukaryotic microbes emerged decades ago, and later investigations confirmed that unicellular fungi and protozoa similarly measure population density to regulate collective activities. In Saccharomyces cerevisiae, aromatic alcohols (2-phenylethanol, tryptophol, tyrosol) serve as QS signals to control filamentous growth, biofilm assembly, and environmental stress responses. Candida albicans employs farnesol to suppress hyphal development while utilizing tyrosol to accelerate germ tube emergence and biofilm maturation. African trypanosomes, including Trypanosoma brucei and related species, generate oligopeptides via secreted peptidases that accumulate as stumpy induction factors (SIFs), triggering a density-dependent shift from proliferative slender forms to transmission-competent stumpy forms essential for tsetse fly infection. QS-based mechanisms influence virulence factors in fungal and protozoan pathogens, affecting their ability to colonize hosts. Exploring QS in eukaryotic organisms opens new possibilities for antifungal treatments and parasite management. By interfering with QS signaling, researchers can disrupt fungal biofilm formation and regulate protozoan development, paving the way for innovative disease control methods.

Climate change is projected to raise sea surface temperatures and intensify diurnal temperature fluctuations (DTF), threatening the survival of both scleractinian corals and octocorals. Litophyton, a common octocoral in Taiwan's shallow reefs, is frequently exposed to large DTF and summer heat stress, making it a suitable model to study thermal resilience. Coral-associated bacterial communities are known to shift under thermal stress, and key bacterial taxa may play crucial roles in host acclimation. This study aimed to address two questions: (1) Can higher DTF mitigate cumulative heat stress in octocorals? (2) If so, what physiological and microbial community changes accompany this effect? To answer these questions, we conducted tank experiments under constant warming and two short-term DTF regimes (± 5 °C and ± 7 °C; baseline 25-27.8 °C), along with a no-fluctuation control. We measured physiological stress indicators, including superoxide dismutase (SOD) and catalase (CAT) activities, and monitored bacterial community dynamics. Our results show that DTF helped maintain stable photosynthetic efficiency (Fv/Fm) compared to constant warming. Notably, significant differences in ROS activity were only observed in the ± 5 °C group, rather than in the larger ± 7 °C group, indicating a measurable alleviation of thermal stress and greater plasticity in Litophyton coping with temperature changes. Moreover, 29.4% more significantly abundant in the ± 7 °C group compared to the control in the core microbiome Endozoicomonas preceded detectable physiological changes in the host, suggesting a potential role in early stress mitigation. These findings deepen our understanding of octocoral holobiont resilience under fluctuating thermal regimes and highlight Endozoicomonas diversity as a potential indicator of Litophyton health.

Microbial necromass carbon (MNC), a key component of soil organic carbon, plays a vital role in aquatic carbon sequestration. Its accumulation and transformation are highly sensitive to environmental changes, particularly in reservoir sediments-critical zones for organic matter storage and biogeochemical cycling. This study investigated the vertical distribution and regulatory mechanisms of MNC in cascade reservoir systems through sediment analysis and metagenomic sequencing. Our findings reveal that MNC constitutes ​​15 ~ 35% of total sediment organic carbon (SeOC)​​, with fungal-derived necromass consistently dominating over bacterial contributions. Metagenomic data highlight distinct functional potentials in carbon cycling, showing that bacterial necromass exhibits higher lability than fungal necromass, as evidenced by shifts in carbohydrate-active enzyme (CAZyme) gene abundances-particularly those involved in glucan and peptidoglycan degradation. Notably, cascade damming introduced ​​spatial heterogeneity in MNC distribution​​, with downstream reservoirs experiencing ​​reduced MNC accumulation​​ due to altered hydrological connectivity and nutrient regimes. These results underscore the ​​pivotal role of MNC in aquatic carbon storage​​ while highlighting the complex interplay between ​​environmental factors, microbial metabolic traits, and anthropogenic disturbances​​ in regulated river systems. Therefore, our findings demonstrate that fungal necromass is a dominant and relatively stable component of sediment carbon, and its dynamics must be integrated to accurately assess and predict carbon sequestration in dammed rivers.