Viruses are ubiquitous in natural systems. By influencing bacterial abundance (BA) and community structure through lysis-lysogenic conversion, viruses are involved in various ecological processes. In agricultural management, nitrogen addition and irrigation should be considered as important factors that can modify soil viral dynamics but have been ignored. In our study, short-term dynamics of autochthonous soil viral and bacterial abundance and diversity after irrigation and urea application were examined in a long-term experimental paddy field. Urea addition delayed the emergence of peak viral abundance for three days, suggesting that viruses are sensitive to N addition. Under short-term eutrophic conditions through urea application, viruses undertake a lysogenic-biased strategy. Moreover, nitrogen-fixing bacteria were most likely specifically lysed in urea-treated soil, which suggests that soil viruses block N accumulation by killing nitrogen-fixing bacteria. To the best of our knowledge, this study is the first to investigate dynamic changes in autochthonous viruses in paddy fields.

Inulin is considered an efficient prebiotic and is beneficial for metabolic diseases via promoting intestinal probiotic enrichment and the metabolites of short-chain fatty acids (SCFAs). However, the effect of inulin on patients with InR deficiencies has seldom been reported. In this study, the lifespan, related gene expression, and gut microbiota of InR^p5545/TM3 (insulin receptor mutant) Drosophila melanogaster under inulin treatment were investigated. The results showed that the lifespan was extended in only males and not in females. Furthermore, distinctly different patterns of gene expression were found between males and females, especially in the insulin/insulin-like growth factor (IGF)-like signalling (IIS) and target of rapamycin (TOR) pathways. Additionally, as a link between inulin and lifespan responses, the gut microbiota was distinctly separated by gender in both the standard diet group and the inulin treatment group, and the relationship between lifespan and the gut microbiota community was stronger in male flies than in females. This study provides preliminary evidence for the gender-dependent lifespan responses to inulin in insulin signalling-deficient Drosophila. However, controls such as wild-type and TM3 flies, and more InR mutant strains with different genetic backgrounds need to be further investigated to elucidate the mechanisms underlying the phenomenon.

Salt stress has long been a prominent obstacle that restricts crop growth, and increasing the L-ascorbic acid (ASA) content of crops is an effective means of alleviating this stress. 2-Keto-L-gulonic acid (2KGA) is a precursor used in industrial ASA production as well as an ASA degradation product in plants. However, to date, no study has investigated the effects of 2KGA on ASA metabolism and salt stress. Here, we evaluated the potential of using 2KGA to improve crop resistance to salt stress (100mM NaCl) through a cultivation experiment of non-heading Chinese cabbage (Brassica campestris ssp. chinensis). The results showed that the leaf and root biomass were significantly improved by 2KGA application. The levels of metabolites and enzymes related to stress resistance were increased, whereas the hydrogen peroxide (H₂O₂) and malondialdehyde (MDA) contents were decreased. Lipid peroxidation and cell membrane damage were alleviated following 2KGA treatment. Positive correlations were found between photosynthetic pigments and organic solutes, ASA and photosynthetic pigments, and ASA and antioxidant enzymes. In contrast, negative correlations were observed between antioxidant enzymes and H₂O₂/MDA. Moreover, the expression levels of L-gulono-1,4-lactone oxidase, GDP-mannose pyrophosphorylase, dehydroascorbate reductase-3, and ascorbate peroxidase were increased by 2KGA treatment. These results suggested that exogenous 2KGA application can relieve the inhibitory effect of salt stress on plant growth, and the promotion of ASA synthesis may represent a critical underlying mechanism. Our findings have significant implications for the future application of 2KGA or its fermentation residue in agriculture.

2-Keto-l-gulonic acid (the precursor of vitamin C) is bio-converted from l-sorbose by mixed fermentation of Ketogulonicigenium vulgare and a helper strain. The helper strain promotes the conversion of 2-KLG by enhancing the growth of K. vulgare, but its growth is greatly inhibited by high concentration of l-sorbose, which consequently influence the 2-KLG production. The aim of this study is to obtain l-sorbose-tolerant helper strain (LHS) by experimental evolution for reduced l-sorbose-inhibition-effect and enhanced 2-KLG productivity in high concentration of l-sorbose. After three steps screening by using our devised screening strategy, three strains (i.e., Bc 21, Bc 47, Bc 50) with high resistance to high concentration of l-sorbose were obtained. The fermentation tests by co-culturing Bc 21 and K. vulgare 418 showed that the production of 2-KLG was increased by 17.9% in 11% l-sorbose medium than that in 8% after 55 h of fermentation and the conversion rate was 89.5%. The results suggested that Bc 21 could be an ideal helper strain for 2-KLG production under high concentration of l-sorbose and demonstrated the feasibility of using experimental evolution to breed LHS for vitamin C production.

Laboratory animals with human microbiome have increasingly been used to study the role of bacteria and host interaction. Drosophila melanogaster, as a model of microbiota-host interaction with high reproductive efficiency and high availability, has always been lacking studies of interaction with human gut microbiome. In this study, we attempted to use antibiotic therapy and human fecal exposure strategy to transfer the human microbiome to the drosophila. The method includes depleting the original intestinal bacteria using a broad-spectrum antibiotic and then introducing human microorganisms by a diet supplemented with donor’s fecal samples. The sequencing results showed that 80–87.5% of the OTUs (Operational Taxonomic Units) from donor feces were adopted by the recipient drosophila following 30 days of observation. In comparison to females, the male recipient drosophila inherited more microbiota from the donor feces and had significantly increased lifespan as well as improved vertical climbing ability. Furthermore, distinctly differential expression patterns for age and insulin-like signaling-related genes were obtained for the male vs. female recipients. Only the male drosophila offspring acquired the characteristics of the donor fecal microbiota.