Screening and Characterization of Two Extracellular Polysaccharide-Producing Bacteria from the Biocrust of the Mu Us Desert.

The extracellular polysaccharide (EPS) matrix embedding microbial cells and soil particles plays an important role in the development of biological soil crusts (BSCs), which is widely recognized as beneficial to soil fertility in dryland worldwide. This study examined the EPS-producing bacterial strains YL24-1 and YL24-3 isolated from sandy soil in the Mu Us Desert in Yulin, Shaanxi province, China. The strains YL24-1 and YL24-3 were able to efficiently produce EPS; the levels of EPS were determined to be 257.22 µg/mL and 83.41 µg/mL in cultures grown for 72 h and were identified as Sinorhizobium meliloti and Pedobacter sp., respectively. When the strain YL24-3 was compared to Pedobacter yulinensis YL28-9T using 16S rRNA gene sequencing, the resemblance was 98.6% and the strain was classified as Pedobacter sp. using physiological and biochemical analysis. Furthermore, strain YL24-3 was also identified as a subspecies of Pedobacter yulinensis YL28-9T on the basis of DNA-DNA hybridization and polar lipid analysis compared with YL28-9T. On the basis of the EPS-related genes of relevant strains in the GenBank, several EPS-related genes were cloned and sequenced in the strain YL24-1, including those potentially involved in EPS synthesis, assembly, transport, and secretion. Given the differences of the strains in EPS production, it is possible that the differences in gene sequences result in variations in the enzyme/protein activities for EPS biosynthesis, assembly, transport, and secretion. The results provide preliminary evidence of various contributions of bacterial strains to the formation of EPS matrix in the Mu Us Desert.

Real-life evaluation of incidence and clinical outcomes of COVID-19 among healthcare workers during pre-vaccination and post-vaccination periods: A cross-sectional impact study.

INTRODUCTION: We aimed to evaluate the prevalence and clinical outcomes of COVID-19 in healthcare workers (HCWs) in the pre-vaccination and post-vaccination periods. In addition, we determined factors associated with the development of COVID-19 after vaccination. METHODOLOGY: In this analytical cross-sectional epidemiological study, HCWs who were vaccinated between January 14, 2021, and March 21, 2021, were included. HCWs were followed up for 105 days after the 2 doses of CoronaVac. Pre-vaccination and post-vaccination periods were compared. RESULTS: A total of 1,000 HCWs were included, 576 patients (57.6%) were male, and the mean age was 33.2 ± 9.6 years. In the last 3 months during the pre-vaccination period, 187 patients had COVID-19, and the cumulative incidence of COVID-19 was 18.7%. Six of these patients were hospitalized. Severe disease was observed in three patients. In the first 3 months post-vaccination period, COVID-19 was detected in 50 patients, and the cumulative incidence of the disease was determined to be 6.1%. Hospitalization and severe disease were not detected. Age (p = 0.29), sex (OR = 1.5, p = 0.16), smoking (OR = 1.29, p = 0.43), and underlying diseases (OR = 1.6, p = 0.26) were not associated with post-vaccination COVID-19. A history of COVID-19 significantly reduced the likelihood of the development of post-vaccination COVID-19 in multivariate analysis (p = 0.002, OR = 0.16, 95% CI = 0.05-0.51). CONCLUSIONS: CoronaVac significantly reduces the risk of SARS-CoV-2 infection and alleviates the severity of COVID-19 in the early period. Additionally, HCWs who have been infected and vaccinated with CoronaVac are less likely to be reinfected with COVID-19.

Compositional and Functional Comparisons of the Microbiota in the Colostrum and Mature Milk of Dairy Goats.

Goat milk is essential for the initial development of kids by providing a great source of commensal bacteria. In this study, we analyzed the microbiota of the milk of 30 healthy Saanen dairy goats. The 30 samples comprised 15 colostrum and 15 mature milk samples, collected from three different farms of Shaanxi Province. Colostrum samples were collected daily for five days post-delivery and mature milk was collected on the 7th, 10th, 20th, 30th, and 40th days. The result showed that microbial alpha diversity was higher in the mature milk compared with that in the colostrum. Linear discriminant analysis effect size (LEfSe) was performed to detect differentially abundant taxa in colostrum and goat milk. According to taxonomy results, Proteobacteria, Firmicutes, Actinobacteria, and Bacteroidetes were the predominant bacteria phyla in both colostrum and mature milk. In addition, lactation stage noticeably influenced the composition of milk microbiota. Specifically, Novosphingobium, Brachybacterium, Psychrobacter, Lactobacillus, Yersinia, Roseateles, Rothia, Sanguibacter, Cloacibacterium, Variovorax, Sphingobacterium, and Coxiella were enriched in the colostrum, while Georgenia, Peptostreptococcus, Bacteroidales, Yaniella, Planomicrobium, Cloacibacterium, Azospirillum, Turicibacter, Cupriavidus, Herbaspirillum, Rhodobacteraceae, and Aeromonadales were the dominant genera in the mature milk. The enriched metabolic functions of the goat milk microbiota were predicted by PICRUSt and classified by KEGG pathway. Moreover, the abundances of environmental information processing, cellular processes pathway, genetic information processing pathway, organismal systems pathway, and metabolism pathway were significantly different between microbiota of colostrum and mature milk. Altogether, our study disclosed the significant difference between the microbial communities of colostrum and mature milk and provided grounds for further research in dairy microbiology.