Functional sustainability of nutrient accumulation by periphytic biofilm under temperature fluctuations

Temperature can fluctuate widely between different seasons, and this may greatly impact many biological processes. However, little is known about its influence on the functioning of benthic microbial communities. Here we investigated the nutrient accumulation capability of periphytic biofilm under temperature fluctuations (17–35°C). Periphytic biofilm maintained the same nutrient accumulation capacity after experiencing the ‘warming-hot-cooling’ temperature fluctuation under both lab and outdoor conditions as those without temperature disturbance. In response to temperature increase, both community composition and species richness changed greatly and the increase in biodiversity was identified as being the underlying mechanism boosting the sustainable function in nutrient accumulation, indicating zero net effects of community changes. These findings provide insights into the underlying mechanisms of how benthic microbial communities adapt to temperature fluctuations to maintain nutrient accumulation capacity and elucidate that periphytic biofilm plays important roles in influencing nutrient cycling in aquatic ecosystems under temperature changes such as seasonal fluctuations

Contribution of periphytic biofilm of paddy soils to carbon dioxide fixation and methane emissions

Rice paddies are major contributors to anthropogenic greenhouse gas emissions via methane (CH4) flux. The accurate quantification of CH4 emissions from rice paddies remains problematic, in part due to uncertainties and omissions in the contribution of microbial aggregates on the soil surface to carbon fluxes. Herein, we comprehensively evaluated the contribution of one form of microbial aggregates, periphytic biofilm (PB), to carbon dioxide (CO2) and CH4 emissions from paddies distributed across three climatic zones, and quantified the pathways that drive net CH4 production as well as CO2 fixation. We found that PB accounted for 7.1%–38.5% of CH4 emissions and 7.2%–12.7% of CO2 fixation in the rice paddies. During their growth phase, PB fixed CO2 and increased the redox potential, which promoted aerobic CH4 oxidation. During the decay phase, PB degradation reduced redox potential and increased soil organic carbon availability, which promoted methanogenic microbial community growth and metabolism and increased CH4 emissions. Overall, PB acted as a biotic converter of atmospheric CO2 to CH4, and aggravated carbon emissions by up to 2,318 kg CO2 equiv ha−1 season−1. Our results provide proof-of-concept evidence for the discrimination of the contributions of surface microbial aggregates (i.e., PB) from soil microbes, and a profound foundation for the estimation and simulation of carbon fluxes in a potential novel approach to the mitigation of CH4 emissions by manipulating PB growth

How Microbial Aggregates Protect against Nanoparticle Toxicity

The increasing use and discharge of nanoparticles (NPs) pose risks to microorganisms that maintain the health of aquatic ecosystems. Although NPs are toxic to microorganisms, they tend to form microbial aggregates to protect themselves. Two main mechanisms account for the reduced toxicity: the dense physical structure acts as a barrier to NP exposure in the interior of the aggregate, and aggregation stabilizes a complex microbial ecosystem that enhances the ability of the community to adapt to prolonged NP exposure. We highlight the opportunities and challenges for managing microbial aggregates in wastewater treatment to remove or control NPs. For example, understanding the resistance mechanisms can help to design smart NPs that are less toxic to useful microorganisms or more toxic towards pathogenic microorganisms

Wide range in estimates of hydrogen emissions from infrastructure

Hydrogen holds tremendous potential to decarbonize many economic sectors, from chemical and material industries to energy storage and generation. However, hydrogen is a tiny, leak-prone molecule that can indirectly warm the climate. Thus, hydrogen emissions from its value chain (production, conversion, transportation/distribution, storage, and end-use) could considerably undermine the anticipated climate benefits of a hydrogen economy. Several studies have identified value chain components that may intentionally and/or unintentionally emit hydrogen. However, the amount of hydrogen emitted from infrastructure is unknown as emissions have not yet been empirically quantified. Without the capacity to make accurate direct measurements, over the past two decades, some studies have attempted to estimate total value chain and component-level hydrogen emissions using various approaches, e.g., assumptions, calculations via proxies, laboratory experiments, and theory-based models (simulations). Here, we synthesize these studies to provide an overview of the available knowledge on hydrogen emissions across value chains. Briefly, the largest ranges in estimated emissions rates are associated with liquefaction (0.15% to 10%), liquid hydrogen transporting and handling (2% to 20%), and liquid hydrogen refueling (2% to 15%). Moreover, present and future value chain emission rate estimates vary widely (0.2% to 20%). Field measurements of hydrogen emissions throughout the value chain are critically needed to sharpen our understanding of hydrogen emissions and, with them, accurately assess the climate impact of hydrogen deployment

MOESM1 of The effects of CO2 and H2 on CO metabolism by pure and mixed microbial cultures

Additional file 1. Pictures of the batch membrane reactor and additional results: qPCR analysis, growth with CO and yeast extract, community structure of the mixed culture, fermentation of CO in non-buffered medium, and carbon balance