Qiong Xie

Alcohol consumption poses a major global public health challenge, with excessive drinkers showing heightened susceptibility to alcoholic liver disease (ALD) – a condition with complex pathogenesis. In this study, we used male BALB/c mice with identical enterotypes to establish a sustained high-dose alcohol-induced liver injury model. The model was created through daily intragastric administration of 52% (v/v) ethanol (10 mL kg⁻¹) for four consecutive weeks, allowing us to investigate the hepatoprotective effects of probiotic supplementation with Clostridium butyricum and Lacticaseibacillus rhamnosus. Results demonstrated that probiotic treatment significantly reduced serum LPS levels while enhancing the expression of tight junction proteins (ZO-1, claudin-3, and occludin), attenuated alcohol-induced elevations in serum alanine aminotransferase (ALT), aspartate aminotransferase (AST), triglyceride (TG) and serum total cholesterol (TC) levels, and effectively mitigated both hepatic injury and dyslipidemia. Mechanistically, probiotics inhibited hepatic lipid accumulation via AMPK pathway regulation, restructured gut microbiota composition, reduced oxidative stress through gut–liver axis modulation (as evidenced by increased hepatic superoxide dismutase (SOD)/catalase (CAT) activities), strengthened intestinal barrier function, and suppressed inflammatory responses via TLR4/NF-κB pathway inhibition (with the corresponding downregulation of TNF-α, IFN-γ, IL-4, IL-6 and MPO). Notably, the probiotic agent also reversed alcohol-induced cognitive and physical impairments, restoring short-term memory and endurance in alcohol-fed mice.

Cronobacter sakazakii is a food-borne pathogen that can thrive in various environments, including the human body. The human body’s physiological temperature exceeds that of the environment (22–30 °C), necessitating adaptations to heat stress during this transition. Managing heat stress is crucial when transitioning from the environment to the human body. In this study, we explored the effect of human body temperature on the growth of planktonic C. sakazakii, as well as its acid resistance, osmotic stress resistance, autoaggregation, and cell surface hydrophobicity. Our study demonstrated that human body temperature facilitated the growth, acid resistance, and osmotic resistance of C. sakazakii, compared to 28 °C. The relationship between human body temperature and phenotypes was studied by comparing gene expression at human and environmental temperatures (37 to 28 °C) using high-throughput sequencing. The results revealed up-regulation in the expression of 626 genes, including genes involved in arginine and proline metabolism, carbon fixation pathways, and nitrogen metabolism. Further analysis showed that human body temperature is essential for the environmental stress resistance of C. sakazakii. It boosts denitrification, betaine transport, and universal stress proteins, supporting membrane integrity and osmoprotectant transport. This study enhances our understanding of the strategies employed by C. sakazakii during its adaptation to the human body.

The ability of Deinococcus bacteria to survive in harsh environments, such as high radiation, extreme temperature, and dryness, is mainly attributed to the generation of unique pigments, especially carotenoids. Although the limited number of natural pigments produced by these bacteria restricts their industrial potential, metabolic engineering and synthetic biology can significantly increase pigment yield and expand their application prospects. In this study, we review the properties, biosynthetic pathways, and functions of key enzymes and genes related to these pigments and explore strategies for improving pigment production through gene editing and optimization of culture conditions. Additionally, studies have highlighted the unique role of these pigments in antioxidant activity and radiation resistance, particularly emphasizing the critical functions of deinoxanthin in D. radiodurans. In the future, Deinococcus bacterial pigments will have broad application prospects in the food industry, drug production, and space exploration, where they can serve as radiation indicators and natural antioxidants to protect astronauts’ health during long-term space flights.

Background: Deinococcus radiodurans (D. radiodurans) is best known for its extreme resistance to diverse environmental stress factors, including ionizing radiation (IR), ultraviolet (UV) irradiation, oxidative stress, and high temperatures. Robust DNA repair system and antioxidant system have been demonstrated to contribute to extreme resistance in D. radiodurans. However, practically all studies on the mechanism underlying D. radiodurans’s extraordinary resistance relied on the treated strain during the post-treatment recovery lag phase to identify the key elements involved. The direct gene or protein changes of D. radiodurans after stress have not yet been characterized. Results: In this study, we performed a proteomics profiling on D. radiodurans right after the heavy ion irradiation treatment, to discover the altered proteins that were quickly responsive to IR in D. radiodurans. Our study found that D. radiodurans shown exceptional resistance to ¹²C⁶⁺ heavy ion irradiation, in contrast to Escherichia coli (E.coli) strains. By using iTRAQ (Isobaric Tags for Relative and Absolute Quantitation)-based quantitative mass spectrometry analysis, the kinetics of proteome changes induced by various dosages of ¹²C⁶⁺ heavy ion irradiation were mapped. The results revealed that 452 proteins were differentially expressed under heavy ion irradiation, with the majority of proteins being upregulated, indicating the upregulation of functional categories of translation, TCA cycle (Tricarboxylic Acid cycle), and antioxidation regulation under heavy ion irradiation. Conclusions: This study shows how D. radiodurans reacts to exposure to ¹²C⁶⁺ heavy ion irradiation in terms of its overall protein expression profile. Most importantly, comparing the proteome profiling of D. radiodurans directly after heavy ion irradiation with research on the post-irradiation recovery phase would potentially provide a better understanding of mechanisms underlying the extreme radioresistance in D. radiodurans.

Confined experiments are carried out to simulate the closed environment of space capsule on the ground. The Chinese Controlled Ecological Life Support System (CELSS) is designed including a closed-loop system supporting 4 healthy volunteers surviving for 180 days, and we aim to reveal the temporal characteristics of the oropharyngeal and nasal microbiota structure in crewmembers stayed 180 days in the CELSS, so as to accumulate the information about microbiota balance associated with respiratory health for estimating health risk in future spaceflight. We investigated the distribution of microorganisms and their dynamic characteristics in the nasal cavity and oropharynx of occupants with prolonged confinement. Based on the 16S rDNA v3–v4 regions using Illumina high-throughput sequencing technology, the oropharyngeal and nasal microbiota were monitored at eight time points during confinement. There were significant differences between oropharyngeal and nasal microbiota, and there were also individual differences among the same site of different volunteers. Analysis on the structure of the microbiota showed that, in the phylum taxon, the nasal bacteria mainly belonged to Actinobacteria, Firmicutes, Proteobacteria, Bacteroidetes, etc. In addition to the above phyla, in oropharyngeal bacteria Fusobacterial accounted for a relatively high proportion. In the genus taxon, the nasal and oropharyngeal bacteria were independent. Corynebacterium and Staphylococcus were dominant in nasal cavity, and Corynebacterium, Streptococcus, and Neisseria were dominant in oropharynx. With the extension of the confinement time, the abundance of Staphylococcus in the nasal cavity and Neisseria in the oropharynx increased, and the index Chao fluctuated greatly from 30 to 90 days after the volunteers entered the CELSS.Conclusion: The structure and diversity of the nasal and oropharyngeal microbiota changed in the CELSS, and there was the phenomenon of migration between occupants, suggesting that the microbiota structure and health of the respiratory tract could be affected by living in a closed environment for a long time.

During a spaceflight, astronauts need to live in a spacecraft on orbit for a long time, and the relationship between humans and microorganisms in the closed environment of space is not the same as on the ground. The dynamic study of microorganisms in confined space shows that with the extension of the isolation time, harmful bacteria gradually accumulate. Monitoring and controlling microbial pollution in a confined environment system are very important for crew health and the sustainable operation of a space life support system. Culture‐based assays have been used traditionally to assess the microbial loads in a spacecraft, and uncultured‐based techniques are already under way according to the NASA global exploration roadmap. High‐throughput sequencing technology has been used generally to study the communities of the environment and human on the ground and shows its broad prospects applied onboard. We here review the recent application of high‐throughput sequencing on space microbiology and analyze its feasibility and potential as an on‐orbit detection technology.

Deinococcus radiodurans is a robust bacterium best known for its capacity to resist to radiation. In this study, the SDS‐PAGE coupled with high‐precision LC‐MS/MS was used to study the D. radiodurans proteome. A total of 1951 proteins were identified which covers 63.18% protein‐coding genes. Comparison of the identified proteins to the key enzymes in amino acid biosyntheses from KEGG database showed the methionine biosynthesis module is incomplete while other amino acid biosynthesis modules are complete, which indicated methionine auxotrophy in D. radiodurans. The subsequent amino acid‐auxotrophic screening has verified methionine instead of other amino acids is essential for the growth of D. radiodurans. With molecular evolutionary genetic analysis, we found the divergence in methionine biosynthesis during the evolution of the common ancestor of bacteria. We also found D. radiodurans lost the power of synthesizing methionine because of the missing metA and metX in two types of methionine biosyntheses. For the first time, this study used high‐coverage proteome analysis to identify D. radiodurans amino acid auxotrophy, which provides the important reference for the development of quantitative proteomics analysis using stable isotope labeling in metabolomics of D. radiodurans and in‐depth analysis of the molecular mechanism of radiation resistance.