Warmer is better for evolutionary rescue, driving a warm-to-cold bias in habitat colonization dynamics.

Evolutionary rescue occurs when populations survive lethal environmental stresses through the rising and fixation of tolerant genotypes. Temperature has long been believed to determine the evolutionary speed of populations and species. Here, we suggest that warmer temperatures can facilitate evolutionary rescue. Moreover, with dispersal among habitats, the advantage in evolutionary rescue for warmer populations may cause a bias in habitat colonization dynamics towards the warm-to-cold direction. We experimentally tested these hypotheses with a model microbial system. Our first experiment showed that bacterial populations at warmer temperatures had a greater chance to evolve resistance and escape the fate of extinction under an antibiotic treatment. In the second experiment, metapopulations that consisted of warm and cold habitats were exposed to the antibiotic stress; local populations that went extinct might be recolonized, and such recolonization events were biased to the warm-to-cold direction. We also examined possible mechanisms underlying the temperature effect on the rapid evolution of resistance in our study system. Our results may help to understand the mechanisms of maintenance of biodiversity and patterns of gene flow among climatic regions, particularly in pest species subject to chemical control treatments.

Enhanced the energy conversion of corn stalk via co-production of photo-fermentation biohydrogen and bioethanol.

Hydrogen-ethanol co-production can significantly improve the energy conversion efficiency of corn stalk (CS). In this study, with CS as the raw material, the co-production characteristics of one-step and two-step photo-fermentation hydrogen production (PFHP) and ethanol production were investigated. In addition, the gas and liquid characteristics of the experiment were analyzed. The kinetics of hydrogen-ethanol co-production was calculated, and the economics of hydrogen and ethanol were analyzed. Results of the experiments indicated that the two-step hydrogen-ethanol co-production had the best hydrogen production performance when the concentration of CS was 25 g/L. The total hydrogen production was 350.08 mL, and the hydrogen yield was 70.02 mL/g, which was 2.45 times higher than that of the one-step method. The efficiency of hydrogen-ethanol co-production was 17.79 %, which was 2.76 times more efficient than hydrogen compared to fermentation with hydrogen. The result provides technical reference for the high-quality utilization of CS.

Preparation of porous lignocellulose biochar adsorbent by cold isostatic pressing pretreatment and study on Hg (II) adsorption properties of C and N dual activity sites.

Utilizing corn straw (CS) mainly composed of lignocellulose to prepare physically modified biochar (PCSB) via cold isostatic pressing (CIP) in order to increase the biochar' s Hg (II) adsorption capacity. The results of the characterization indicated that CIP pretreatment renders PCSB-400' s structure more porous and higher N content of 16.65 %, leading to more N-containing functional groups partaking in the adsorption process. PCSB-400 adsorbed Hg (II) primarily via C/N synergistic complexation and electrostatic attraction between pores, in addition to the presence of redox reactions of surface functional groups on PCSB-400. The adsorption experiment reveals that PCSB-400 has a high selectivity for the adsorption of Hg (II). The adsorption process of Hg (II) by PCSB-400 more closely resembles the Langmuir model and pseudo-first-order adsorption kinetics equation. The adsorption quantity at saturation is 282.52 mg/g at 25 °C. This paper provided an effective idea to selectively remove Hg (II) in wastewater.

Suffering makes you weaker: Limited evolutionary adaptation in competitively inferior populations.

Interspecific competition can hinder populations from evolutionarily adapting to abiotic environments, particularly by reducing population size and niche space; and feedback may arise between competitive ability and evolutionary adaptation. Here we studied populations of two model bacterial species, Escherichia coli and Pseudomonas fluorescens, that evolved in monocultures and cocultures for approximately 2400 generations at three temperatures. The two species showed a reversal in competitive dominance in cocultures along the temperature gradient. Populations from cocultures where they had been competitively dominant showed the same magnitude of fitness gain as those in monocultures. However, competitively inferior populations in cocultures showed limited abiotic adaptation compared with those in monocultures. The inferior populations in cocultures were also more likely to evolve weaker interspecific competitive ability, or go extinct. The possible competitive ability-adaptation feedback may have crucial consequences for population persistence.

Nanobubble technology to enhance energy recovery from anaerobic digestion of organic solid wastes: Potential mechanisms and recent advancements.

Nanobubble (NB) technology has gained popularity in the environmental field owing to its distinctive characteristics and ecological safety. More recently, the application of NB technology in anaerobic digestion (AD) systems has been proven to promote substrate degradation and boost the production of biogas (H2 and/or CH4). This review presents the recent advancements in the application of NB technology in AD systems. Meanwhile, it also sheds light on the underlying mechanisms of NB technology that contribute to the enhanced biogas production from AD of organic solid wastes. Specifically, the working principles of the NB generator are first summarized, and then the structure of the NB generator is optimized to accommodate the demand for NB characteristics in the AD system. Subsequently, it delves into a detailed discussion of how the addition of nanobubble water (NBW) affects AD performance and the different factors that NB can potentially contribute. As a simple and environmentally friendly additive, NBW was commonly used in the AD process to enhance the fluidity and mass transfer characteristics of digestate. Additionally, NB has the potential to enhance the functionality of different types of microbial enzymes that play crucial roles in the AD process. This includes boosting extracellular hydrolase activities, optimizing coenzyme F420, and improving cellulase function. Finally, it is proposed that NBW has development potential for the pretreatment of substrate and inoculum, with future development being directed towards this aim.

Biological fermentation pilot-scale systems and evaluation for commercial viability towards sustainable biohydrogen production.

Featuring high caloric value, clean-burning, and renewability, hydrogen is a fuel believed to be able to change energy structure worldwide. Biohydrogen production technologies effectively utilize waste biomass resources and produce high-purity hydrogen. Improvements have been made in the biohydrogen production process in recent years. However, there is a lack of operational data and sustainability analysis from pilot plants to provide a reference for commercial operations. In this report, based on spectrum coupling, thermal effect, and multiphase flow properties of hydrogen production, continuous pilot-scale biohydrogen production systems (dark and photo-fermentation) are established as a research subject. Then, pilot-scale hydrogen production systems are assessed in terms of sustainability. The system being evaluated, consumes 171,530 MJ of energy and emits 9.37 t of CO2 eq when producing 1 t H2, and has a payback period of 6.86 years. Our analysis also suggests future pathways towards effective biohydrogen production technology development and real-world implementation.

Enhancement of biohydrogen production by photo-fermentation of corn stover via visible light catalyzed titanium dioxide/activated carbon fiber.

In this study, titanium dioxide/activated carbon fiber (TiO2/ACF) was synthesized by liquid-phase deposition method and the effect of TiO2/ACF on the performance of photo-fermentation biohydrogen production (PFHP) from corn stover under visible light catalysis was discussed. Results show the maximum cumulative hydrogen yield (CHY) obtained under the optimal conditions was 74.0 ± 1.3 mL/g TS with TiO2/ACF addition of 100 mg/L, which was twice that without TiO2/ACF addition (36.9 ± 1.0 mL/g TS). Initial pH value had the most significant effect on CHY. The addition of TiO2/ACF promoted the metabolic pathway of nitrogenase to reduce H+ produced by consuming acetic acid and butyric acid to hydrogen, and also shortened the photo-fermentation period. By scanning electron microscopy and X-ray diffraction analysis, the morphology and phase structure of TiO2/ACF after PFHP did not change significantly. This study laid the foundation for the reuse of TiO2 and its practical application in PFHP.

Loss and recovery of ecological diversity associated with evolutionary rescue in abruptly and gradually deteriorating environments.

Populations may survive environmental deterioration by evolutionary adaptation. However, such evolutionary rescue events may be associated with ecological costs, such as reduction in growth performance and loss of ecologically important genetic diversity. Those negative ecological consequences may be mitigated by additional adaptive evolution. Both the ecological costs and the opportunities for additional evolution are contingent on the severity of environmental deterioration. Here, we hypothesize that populations evolutionarily rescued from faster, relative to slow, environmental deterioration suffer more severe long-term fitness decline and diversity loss. An experiment with the model adaptive radiation of bacterium Pseudomonas fluorescens exposed to abruptly or gradually increased antibiotic stress supported our hypothesis. The effect of additional adaptive evolution in recovering population size and ecological diversity was far from perfect. Cautions are therefore needed in predicting the role of rapid evolution for mitigating the impacts of environmental changes, in particular very fast environmental deterioration. We also found that bacterial populations rescued from gradually increased antibiotic stress evolved higher levels of antibiotic resistance, lending more support to aggressive chemotherapy in pathogen control.

Bio-hydrogen-producing Potential Evaluation and Capacity Enhancement from Tobacco Processing Leftovers by Photo-fermentation Under Diverse Initial pH.

The use of tobacco growing and processing residues for bio-hydrogen production is an effective exploration to broaden the source of bio-hydrogen production raw materials and realize waste recycling. In this study, bio-hydrogen-producing potential was evaluated and the effect of diverse initial pH on hydrogen production performance was investigated. The cumulative hydrogen yield (CHY) and the properties of fermentation liquid were monitored. The modified Gompertz model was adopted to analyze the kinetic characteristics of photo-fermentation bio-hydrogen production process. Results showed that CHY increased firstly and then decreased with the increase of initial pH. Highest CHY and hydrogen production rate of appeared at the initial pH of 8, which were 257.7 mL and 6.15 mL/h, respectively. The acidic initial pH was found to severely limit the bio-hydrogen production capacity. The correlation coefficients (R2) of hydrogen production kinetics parameters were all greater than 0.99, meaning that the fitting effect was good. The main metabolites of bacteria in the system were acetic acid, butyric acid, and ethanol, and the consumption of acetic acid was promoted with the increase of initial pH.

The effectiveness of artificial microbial community selection: a conceptual framework and a meta-analysis.

The potential for artificial selection at the community level to improve ecosystem functions has received much attention in applied microbiology. However, we do not yet understand what conditions in general allow for successful artificial community selection. Here we propose six hypotheses about factors that determine the effectiveness of artificial microbial community selection, based on previous studies in this field and those on multilevel selection. In particular, we emphasize selection strategies that increase the variance among communities. We then report a meta-analysis of published artificial microbial community selection experiments. The reported responses to community selection were highly variable among experiments; and the overall effect size was not significantly different from zero. The effectiveness of artificial community selection was greater when there was no migration among communities, and when the number of replicated communities subjected to selection was larger. The meta-analysis also suggests that the success of artificial community selection may be contingent on multiple necessary conditions. We argue that artificial community selection can be a promising approach, and suggest some strategies for improving the performance of artificial community selection programs.