Principles of Language Learning and Teaching

In the post-COVID-19 pandemic era, various antimicrobials have emerged and concentrated in waste-activated sludge (WAS), affecting the biological treatment of WAS. However, there is still a knowledge gap in the dynamic response and adaptive mechanism of anaerobic microbiome under exogenous antimicrobial stress. This study found that methylisothiazolinone (MIT, as a typic antimicrobial) caused an interesting lag effect on the volatile fatty acids (VFAs) promotion in the WAS anaerobic fermentation process. MIT was effective to disintegrate the extracellular polymeric substances (EPS), and those functional anaerobic microorganisms were easily exposed and negatively impacted by the MIT interference after the loss of protective barriers. Correspondingly, the ecological interactions and microbial metabolic functions related to VFA biosynthesis (e.g., pyruvate metabolism) were downregulated at the initial stage. The syntrophic consortia gradually adapted to the interference and attenuated the MIT stress by activating chemotaxis and resistance genes (e.g., excreting, binding, and inactivating). Due to the increased bioavailable substrates in the fermentation systems, the dominant microorganisms (i.e., Clostridium and Caloramator) with both VFAs production and MIT-tolerance functions have been domesticated. Moreover, MIT disrupted the syntrophic interaction between acetogens and methanogens and totally suppressed methanogens' metabolic activities. The VFA production derived from WAS anaerobic fermentation was therefore enhanced due to the interference of antimicrobial MIT stress. This work deciphered dynamic changes and adaptive evolution of anaerobic syntrophic consortia in response to antimicrobial stress and provided guidance on the evaluation and control of the ecological risks of exogenous pollutants in WAS treatment. 

Dynamic microbiome disassembly and evolution induced by antimicrobial methylisothiazolinone in sludge anaerobic fermentation for volatile fatty acids generation.

Anaerobic fermentation is a promising approach for sludge treatment, although it is frequently hindered by the tight structure of extracellular polymeric substances (EPS) and limited metabolic activities. This work firstly discovered that methylisothiazolinone (MIT, a commonly used antimicrobial agent in water treatment) effectively disintegrated the sludge structure and stimulated metabolic pathways, leading to efficient volatile fatty acids (VFAs) production. The presence of MIT (ranging from 10 to 40 mg/g TSS) contributed to the acidogenic process but strongly restrained the methanogenesis, and the distinct interfering effect is highly associated with the MIT dose. The VFAs accumulation reached a maximum of 1776.7 mg COD/L (5.2 times of control) but faced a complete inhibition of methanogenic activity at 40 mg/g TSS. Spectroscopic and molecular docking analysis revealed that MIT interacted with and disrupted the EPS (mainly proteins) structure by forming hydrogen bonds with N-H groups. This disruption facilitated the release of biodegradable organics, which served as fermentation substrates. Furthermore, the MIT-mediated improvement selectively enriched the hydrolytic-acidifying bacteria (i.e., Clostridium and Caloramator) and stimulated the associated metabolic functions, particularly in the uptake, hydrolysis, and metabolism of amino acids considering the high expressions of encoding genes (e.g., oppA, pepP, gdhA). However, methanogens' reproductive and metabolic abilities were suppressed due to their inefficient response and adaptation to MIT. This suppression was evident through downregulated genetic expressions involved in DNA replication and aminoacyl-tRNA synthesis. Consequently, a decline in methanogens abundance (e.g., Methanothrix, and Methanosarcina) and methanogenic activity occurred, impeding the consumption of VFAs. This work provided an innovative niche to promote resource recovery in the sludge anaerobic system and deciphered the underlying mechanisms at both biochemical interactive steps and microbial genetic traits. 

Multifaceted roles of methylisothiazolinone intervention in sludge disintegration and acidogenic and methanogenic pathways for efficient carboxylate production during anaerobic fermentation

Surfactant aggravated the antibiotic's stress on antibiotic resistance genes proliferation by altering antibiotic solubilization and microbial traits in sludge anaerobic fermentation.

Consciousness-Raising Activities:"For and Since"and"Too and Either"

Exogenous contaminants often co-occur in waste-activated sludge (WAS), but their potential mutual interactions and joint effects on the WAS treatment are less concerning. This work revealed that surfactants induced and aggravated the toxicity of Fe2O3 nanoparticles (NPs) in volatile fatty acids (VFAs)’ biosynthesis during WAS anaerobic fermentation. The VFA production exhibited a 40.1 and 20.3% inhibition compared to the individual LAS and CTAB reactors, respectively. A mechanistic exploration implied that the WAS solubilization, hydrolysis, and acidification steps during VFA generation were restrained. Moreover, the Fe2O3 NPs’ and surfactants’ coexistence suppressed the acid-forming bacteria (i.e., Saprospiraceae_uncultured, Bacteroidetes vadinHA17_norank) and the homologous metabolic functions responsible for substrate hydrolysis (e.g., malZ and pepD), intracellular metabolism (e.g., pfkA and gdhA), VFAs’ biosynthesis (e.g., bkdA and ackA), and ATP generation (e.g., atpE and atpH), resulting ultimately in VFAs’ reduction. Furthermore, the surfactants contributed to the dispersibility of coexisting Fe2O3 NPs to maintain the high reactivity of NPs. Besides, the WAS disintegration triggered by surfactants increased the interactions between Fe2O3 NPs and microorganisms, thereby aggravating toxicity. Our study provides novel insights into environmental behaviors of co-occurring contaminants in the anaerobic environment and provides in-depth guidance for practical WAS treatment. 

Surfactants Aggravated the Biotoxicity of Fe2O3 Nanoparticles in the Volatile Fatty Acids’ Biosynthesis during Sludge Anaerobic Fermentation

Grammar teaching has been a heated topic in the field of foreign language learning and teaching. The research of grammar teaching lies between the continuum of a series of grammar teaching dilemmas. This paper first reviews the pendulum movements of researches and their related grammar teaching approaches and methods, discusses three dilemmas involved with grammar teaching, and draws conclusions regarding to how to address with dilemmas. In view of the current situation in second language teaching, a consciousness-raising grammar teaching approach is discussed from the aspects of its concepts, characteristics, patterns and application in foreign language teaching.

/pdf/a-consciousness-raising-grammar-teaching-approach-based-on-47g0m99xa9.pdf

A Consciousness-raising Grammar Teaching Approach Based on Grammar Teaching Dilemmas

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Surfactants Aggravated the Biotoxicity of Fe2O3 Nanoparticles in the Volatile Fatty Acids’ Biosynthesis during Sludge Anaerobic Fermentation

A Consciousness-raising Grammar Teaching Approach Based on Grammar Teaching Dilemmas