Inter-bacterial mutualism promoted by public goods in a system characterized by deterministic temperature variation.

Mutualism is commonly observed in nature but not often reported for bacterial communities. Although abiotic stress is thought to promote microbial mutualism, there is a paucity of research in this area. Here, we monitor microbial communities in a quasi-natural composting system, where temperature variation (20 °C-70 °C) is the main abiotic stress. Genomic analyses and culturing experiments provide evidence that temperature selects for slow-growing and stress-tolerant strains (i.e., Thermobifida fusca and Saccharomonospora viridis), and mutualistic interactions emerge between them and the remaining strains through the sharing of cobalamin. Comparison of 3000 bacterial pairings reveals that mutualism is common (~39.1%) and competition is rare (~13.9%) in pairs involving T. fusca and S. viridis. Overall, our work provides insights into how high temperature can favour mutualism and reduce competition at both the community and species levels.

Risk Factors of Hypoxemia in the Postanesthesia Care Unit After General Anesthesia in Children.

PURPOSE: To investigate the incidence and risk factors of hypoxemia in the postanesthesia care unit (PACU) after general anesthesia in children. DESIGN: A retrospective observational study. METHODS: Elective surgical patients (N = 3,840 patients) treated in a pediatric hospital were divided into a hypoxemia group and a nonhypoxemia group according to the presence of hypoxemia following transport to the PACU. The clinical data of the 3,840 patients were compared between these two groups to evaluate factors that were linked to the development of postoperative hypoxemia. Factors that showed a statistically significant difference (P < .05) in single-factor tests were then examined in multivariate regression analyses to identify hypoxemia risk factors. FINDINGS: In our study group of 3,840 patients, 167 (4.35%) patients developed hypoxemia, with an incidence of 4.35%. Univariate analysis indicated that age, weight, anesthesia method, and operation type were significantly associated with hypoxemia. Logistic regression analysis indicated that operation type was associated with hypoxemia. CONCLUSIONS: Surgery type is a primary risk factor for pediatric hypoxemia in the PACU following general anesthesia. Patients undergoing oral surgery are more prone to hypoxemia and should be more intensively monitored to ensure timely treatment if required.

Core fungal species strengthen microbial cooperation in a food-waste composting process.

In ecosystem engineering research, the contribution of microbial cooperation to ecosystem function has been emphasized. Fungi are one of the predominant decomposers in composting, but thus far, less attention has been given to fungal than to bacterial cooperation. Therefore, network and cohesion analyses were combined to reveal the correlation between fungal cooperation and organic matter (OM) degradation in ten composting piles. Positive cohesion, reflecting the cooperation degree, was positively linked to the degradation rate of OM. From the community perspective, core species (i.e., Candida tropicalis, Issatchenkia orientails, Kazachstania exigua, and Dipodascus australiensis) with high occurrence frequency and abundance were the key in regulating positive cohesion. These species were highly relevant to functional genera associated with OM degradation in both fungal and bacterial domains. Therefore, focusing on these core fungal species might be an appropriate strategy for targeted regulation of functional microbes and promotion of degradation rates.

Microbial cooperation promotes humification to reduce antibiotic resistance genes abundance in food waste composting.

Antibiotic resistance genes (ARGs) fate in a full-scale Food waste (FW) facility was investigated. Results showed that with the changes in ARGs, microbial networks could be naturally divided into two clusters, named as the ARGs increasing group (AI group) and the ARGs decreasing group (AD group). The significant difference between two groups (i.e. stronger microbial competition in the AI group and stronger microbial cooperation in the AD group) implied that the variation in ARGs over time were caused by a switch between competition and cooperation. These results indicated that microbial competition might increase ARGs abundance, while cooperation might reduce it. Meanwhile, structural-equation-model (SEM model) showed that humification indexes (e.g. GI value) was an indicator for characterizing microbial interactions and ARGs. The results of the linear model further confirmed that mature compost (GI values > 92.6 %) could reduce the risk of ARGs.

Interval aeration improves degradation and humification by enhancing microbial interactions in the composting process.

Five full-scale food waste composts were conducted under different aeration frequencies (no aeration, aeration at different intervals, and continuous aeration) to reveal the optimal strategy and its microbial mechanisms. The highest degradation rate (77.2%) and humus content (29.3%) were observed in Treatment D with interval aeration (aeration 20 min, pause 10 min). Aeration influenced the degradation and humification rate by regulating microbial interactions. The microbial interactions peaked in Treatment D, with a 1.30-fold increase. In terms of the microbial community, Thermobifida was a key genus for improving positive cohesion, fulfilling three criteria (high abundance, high occurrence frequency, and significant differences between treatments). The aeration strategy employed in Treatment D not only increased relative abundance of Thermobifida (1.2 times higher) but also strengthened interaction between it and functional genera (34 nodes). Overall, interval aeration, featured by 20 min aeration and 10 min pause, could increase microbial interactions and improve composting efficiency.