Optimized methyl donor and reduced precursor degradation pathway for seleno-methylselenocysteine production in Bacillus subtilis.

BACKGROUND: Seleno-methylselenocysteine (SeMCys) is an effective component of selenium supplementation with anti-carcinogenic potential that can ameliorate neuropathology and cognitive deficits. In a previous study, a SeMCys producing strain of Bacillus subtilis GBACB was generated by releasing feedback inhibition by overexpression of cysteine-insensitive serine O-acetyltransferase, enhancing the synthesis of S-adenosylmethionine as methyl donor by overexpression of S-adenosylmethionine synthetase, and expressing heterologous selenocysteine methyltransferase. In this study, we aimed to improve GBACB SeMCys production by synthesizing methylmethionine as a donor to methylate selenocysteine and by inhibiting the precursor degradation pathway. RESULTS: First, the performance of three methionine S-methyltransferases that provide methylmethionine as a methyl donor for SeMCys production was determined. Integration of the NmMmt gene into GBACB improved SeMCys production from 20.7 to 687.4 µg/L. Next, the major routes for the degradation of selenocysteine, which is the precursor of SeMCys, were revealed by comparing selenocysteine hyper-accumulating and non-producing strains at the transcriptional level. The iscSB knockout strain doubled SeMCys production. Moreover, deleting sdaA, which is responsible for the degradation of serine as a precursor of selenocysteine, enhanced SeMCys production to 4120.3 µg/L. Finally, the culture conditions in the flasks were optimized. The strain was tolerant to higher selenite content in the liquid medium and the titer of SeMCys reached 7.5 mg/L. CONCLUSIONS: The significance of methylmethionine as a methyl donor for SeMCys production in B. subtilis is reported, and enhanced precursor supply facilitates SeMCys synthesis. The results represent the highest SeMCys production to date and provide insight into Se metabolism.

Biological Functions and Cross-Kingdom Host Gene Regulation of Small RNAs in Lactobacillus plantarum-Derived Extracellular Vesicles.

Extracellular vesicle-mediated transfer of microRNAs is a novel mode of cell-to-cell genetic transmission. Extracellular vesicles produced by microbes have been shown to contain significant quantities of physiologically active molecules such as proteins, lipids, and RNA, which could be transported to host cells and play a key role in both inter-kingdom signaling and physiological responses. In this study, we identified sRNAs by sequencing small RNAs (sRNAs) from Lactobacillus plantarum-derived extracellular vesicles (LDEVs) and detected the expression levels of vesicular sRNAs using quantitative reverse transcription-polymerase chain reaction (RT-PCR), which demonstrated the presence of microRNA-sized RNAs (msRNAs) within these vesicles. We chose sRNA71, a highly expressed msRNA, for further investigation, predicted its potential target genes for the human genome, and indicated that it could be translocated into mammalian cells. The biological functions of this sRNA71 were subsequently explored through cellular proteomics, western blot, and luciferase reporter assay. According to the findings, transfection with synthetic sRNA71 mimics substantially reduced Tp53 expression in HEK293T cells and suppressed the gene expression through binding to the 3' UTR of Tp53 mRNA. In conclusion, it is hypothesized that microbial-derived extracellular vesicles serve as carriers of functional molecules such as sRNAs, which play an essential role in regulating microbial-host communication.

Intraoperative hypotension, oliguria and operation time are associated with pulmonary embolism after radical resection of head and neck cancers: a case control study.

BACKGROUND: Postoperative pulmonary embolism (PE) is a serious thrombotic complication in the patients with otolaryngologic cancers. We investigated the risk factors associated with postoperative PE after radical resection of head and neck cancers. METHODS: A total of 3512 patients underwent head and neck cancers radical resection from 2013 to 2019. A one-to-three control group without postoperative PE was selected matched by age, gender, and type of cancer. Univariate analyses were performed for the perioperative patient data including hemodynamic management factors. Conditional logistic regression was used to analyze the factors and their odds ratios. RESULTS: Postoperative PE was prevalent in 0.85% (95%CI = 0.56-1.14). Univariate analyses showed that a high ASA grade, high BMI, and smoking history may be related to postoperative PE. There was significantly difference in operation time between the two groups, especially for> 4 h [22(78.6%) vs 43(51.2%), P = .011]. The urine output was lower [1.37(0.73-2.21) ml·kg- 1·h- 1 vs 2.14(1.32-3.46) ml·kg- 1·h- 1, P = .006] and the incidence of oliguria was significantly increased (14.3% vs 1.2%, P = .004) in the PE group. Multivariable conditional logistic regression showed postoperative PE were associated with the cumulative duration for intraoperative hypotension (OR = 2.330, 95%CI = 1.428-3.801, P = .001), oliguria (OR = 14.844, 95%CI = 1.089-202.249, P = .043), and operation time > 4 h (OR = 4.801, 95%CI = 1.054-21.866, P = .043). CONCLUSIONS: The intraoperative hypotension, oliguria, and operation time > 4 h are risk factors associated with postoperative PE after radical resection of head and neck cancers. Improving intraoperative hemodynamics management to ensure adequate blood pressure and urine output may reduce the occurrence of such complications.

Massilia atriviolacea sp. nov., a dark purple-pigmented bacterium isolated from soil.

A bacterial strain, designated SODT, with Gram-stain-negative and motile rod-shaped cells, was isolated from soil in Hefei, PR China, and was characterized using a polyphasic approach. Phylogenetic analysis based on 16S rRNA gene sequences indicated that strain SODT belonged to the genus Massilia and showed the highest similarities to Massilia violaceinigra B2T (99.3 %), followed by Massilia glaciei B448-2T (98.7 %), Massilia eurypsychrophila CGMCC 1.12828T (98.6 %) and Rugamonas rubra CCM3730T (97.8 %). Average nucleotide identity and digital DNA-DNA hybridization values between genome sequences of strain SODT and the closely related species ranged from 77.1 to 89.3% and from 22.2 to 34.7 %. The DNA G+C content of strain SODT was 65.4 mol%. Strain SODT contained Q-8 as the major ubiquinone and the dominant fatty acids were summed feature 3 (C16 : 1ω7c and/or C15 : 0iso 2-OH; 58.5 %), C16 : 0 (26.8 %) and C18 : 1ω7c (5.0 %). The major polar lipids were diphosphatidylglycerol, phosphatidylethanolamine and phosphatidylglycerol. On the basis of the evidence presented in this study, strain SODT represents a novel species of the genus Massilia, for which the name Massiliaatriviolacea sp. nov. is proposed. The type strain is SODT (=KCTC 62720T=LMG 30840T).