Halocin H4 is activated through cleavage by halolysin HlyR4.

Halocins are antimicrobial peptides secreted by haloarchaea capable of inhibiting the growth of other haloarchaea or bacteria. Halocin H4 (HalH4) is secreted by the model halophilic archaeon Haloferax mediterranei ATCC 33500. Despite attempts to express halH4 heterologously in Escherichia coli and subsequent careful renaturation procedures commonly employed for haloarchaeal proteins, no active halocin was obtained. However, it was discovered that the antihaloarchaeal activity of this halocin could be activated through cleavage by halolysin R4 (HlyR4), a serine protease also secreted by Hfx. mediterranei ATCC 33500. Replacement of the cysteine at the number 115 amino acid with glycine and deletion of the internal trans-membrane region (15 aa) markedly abolished HalH4's antihaloarchaeal activity. Compared to the N-terminus, the C-terminal amino acid sequence was found to be more crucial for HalH4 to exert its antihaloarchaeal activity. Mass spectrometry analysis revealed that the biologically active antihaloarchaeal peptide produced after hydrolytic cleavage by HlyR4 was the C-terminus of HalH4, suggesting a potential mechanism of action involving pore formation within competitor species' cell membranes. Taken together, this study offers novel insights into the interplay between halocins and secreted proteases, as well as their contribution to antagonistic interaction within haloarchaea. IMPORTANCE: The antihaloarchaeal function of halocin H4 (HalH4) can be activated by extracellular proteases from haloarchaea, as demonstrated in this study. Notably, we report the first instance of halocin activation through proteolytic cleavage, highlighting its significance in the field. The C-terminus of HalH4 (CTH4) has been identified as the antihaloarchaeal peptide present in hydrolysates generated by HlyR4. The CTH4 exhibited inhibitory activity against a range of haloarchaeal species (Haloarchaeobius spp., Haloarcula spp., Haloferax spp., Halorubellus spp., and Halorubrum spp.), as well as selected bacterial species (Aliifodinibius spp. and Salicola spp.), indicating its broad-spectrum inhibitory potential across domains. The encoding gene of halocin HalH4, halH4, from the model halophilic archaeon Haloferax mediterranei ATCC 33500 can be expressed in Escherichia coli without codon optimization.

Biodegradation of phthalic acid esters (PAEs) by Janthinobacterium sp. strain E1 under stress conditions.

Phthalates esters (PAEs) are a kind of polymeric material additives widely been added into plastics to improve products' flexibility. It can easily cause environmental pollution which are hazards to public health. In this study, we isolated an efficient PAEs degrading strain, Janthinobacterium sp. E1, and determined its degradation effect of di-2-ethylhexyl phthalate (DEHP) under stress conditions. Strain E1 showed an obvious advantage in pollutants degradation under various environmental stress conditions. Degradation halo clearly occurred around the colony of strain E1 on agar plate supplemented with triglyceride. Strain E1's esterase is a constitutively expressed intracellular enzyme. The esterase purified from strain E1 showed a higher catalytic effect on short-chain PAEs than long-chain PAEs. The input of DEHP, DBP (dibutyl phthalate) and DMP (dimethyl phthalate) into the tested soil did not change the species composition of soil prokaryotic community, but altered the dominant species in specific environmental conditions. And the community diversity and richness decreased to a certain extent. However, the diversity and richness of the microbial community were improved after the contaminated soil was treated with the strain E1. Our results also suggested that strain E1 exhibited a tremendous potential in environmental bioremediation in the real environment, which provides a new insight into the elimination of the pollutants contamination in the urban environment.

Genomic, Physiological, Biochemical, and Phenotypic Evidences Reveal a New Species, Halomicroarcula salaria sp. nov.

An extremely halophilic archaeon strain named FL173T was isolated from a salt mine (Anhui Province, China). Colonies on agar plate are orange-red, moist, and opaque. Cells are motile, Gram-stain-negative, polymorphic, and lyse in distilled water. Cells are able to grow at temperatures, NaCl concentrations, and pH ranging from 20 to 50 °C (optimum 42 °C), 2.6 to 5.1 M NaCl concentration (optimum 3.4 M), and 5.5 to 9.5 pH (optimum 7.0), respectively. Mg2+ is not necessary for growth. The major polar lipids of strain FL173T were phosphatidylglycerol (PG), phosphatidylglycerol phosphate methyl ester (PGP-Me), phosphatidylglycerol sulfonate (PGS), sulfonated mannosyl glycolipid (S-DGD-1). It has two copies of the 16S rRNA gene, which share the highest sequence similarity (93.04-99.02% sequence similarity) to the 16S rRNA genes of Halomicroarcula salinisoli F24AT, respectively. The rpoB' gene of strain FL173T showed the highest sequence similarity (93.76%) to that of H. salinisoli F24AT. The genome-based analysis showed that the average amino-acid identity (AAI), orthologous average nucleotide identity (ANI) and in silico DNA-DNA hybridization values between strains FL173T and H. salinisoli F24AT were 84.80%, 85.29%, and 29.70%, respectively, which are far below the threshold for the delineation of a prokaryotic new species. The DNA G+C content of strain FL173T is 64.9%. Genomic, physiological, biochemical, and phenotypic evidences showed that strain FL173T (CGMCC 1.18851=NBRC 114260) represents a new species of the genus Halomicroarcula, for which the name Halomicroarcula salaria sp. nov. is proposed.

Effects of the synergistic treatments of arbuscular mycorrhizal fungi and trehalose on adaptability to salt stress in tomato seedlings.

Arbuscular mycorrhizal fungi (AMF) could establish symbiosis with plant roots, which enhances plant resistance to various stresses, including drought stress and salt stress. Besides AMF, chemical stimulants such as trehalose (Tre) can also play an important role in helping plants alleviate damage of adversity. However, the mechanism of the effect of AMF combined with chemicals on plant stress resistance is unclear. The objective of this study was to explore the synergistic effects of Claroideoglomus etunicatum AMF and exogenous Tre on the antioxidant system, osmoregulation, and resistance-protective substance in plants in response to salt stress. Tomato seedlings were inoculated with Claroideoglomus etunicatum and combined with exogenous Tre in a greenhouse aseptic soil cultivation experiment. We measured the arbuscular mycorrhizal symbiont development, organic matter content, and antioxidant enzyme activity in tomato seedlings. Both AMF and Tre improved the synthesis of chlorophyll content in tomato seedlings; regulated the osmotic substance including soluble sugars, soluble protein, and proline of plants; and increased the activity of superoxide dismutase, peroxidase, and catalase. The combination of AMF and Tre also reduced the accumulation of malondialdehyde and alleviated the damage of harmful substances to plant cells in tomato seedlings. We studied the effects of AMF combined with extraneous Tre on salt tolerance in tomato seedlings, and the results showed that the synergistic treatment of AMF and Tre was more efficient than the effects of AMF inoculation or Tre spraying separately by regulating host substance synthesis, osmosis, and antioxidant enzymes. Our results indicated that the synergistic effects of AMF and Tre increased the plant adaptability against salt damage by enhancing cell osmotic protection and cell antioxidant capacity. IMPORTANCE: AMF improve the plant adaptability to salt resistance by increasing mineral absorption and reducing the damage of saline soil. Trehalose plays an important role in plant response to salt damage by regulating osmotic pressure. Together, the use of AMF and trehalose in tomato seedlings proved efficient in regulating host substance synthesis, osmosis, and antioxidant enzymes. These synergistic effects significantly improved seedling adaptability to salt stress by enhancing cell osmotic protection and cell antioxidant capacity, ultimately reducing losses to crops grown on land where salinization has occurred.

Expression, purification, and enzymatic characterization of an extracellular protease from Halococcus salifodinae.

Extracellular proteases from halophilic archaea displays increased enzymatic activities in hypersaline environment. In this study, an extracellular protease-coding gene, hly34, from the haloarchaeal strain Halococcus salifodinae PRR34, was obtained through homologous search. The protease activity produced by this strain at 20% NaCl, 42 °C, and pH 7.0 was 32.5 ± 0.5 (U·mL-1). The codon-optimized hly34 which is specific for Escherichia coli can be expressed in E. coli instead of native hly34. It exhibits proteolytic activity under a wide range of low- or high-salt concentrations, slightly acidic or alkaline conditions, and slightly higher temperatures. The Hly34 presented the highest proteolytic activity at 50 °C, pH 9.0, and 0-1 M NaCl. It was found that the Hly34 showed a higher enzyme activity under low-salt conditions. Hly34 has good stability at different NaCl concentrations (1-4 M) and pH (6.0-10.0), as well as good tolerance to some metal ions. However, at 60 °C, the stability is reduced. It has a good tolerance to some metal ions. The proteolytic activity was completely inhibited by phenylmethanesulfonyl fluoride, suggesting that the Hly34 is a serine protease. This study further deepens our understanding of haloarchaeal extracellular protease, most of which found in halophilic archaea are classified as serine proteases. These proteases exhibit a certain level of alkaline resistance and moderate heat resistance, and they may emerge with higher activity under low-salt conditions than high-salt conditions. The protease Hly34 is capable of degrading a number of proteins, including substrate proteins, such as azocasein, whey protein and casein. It has promising applications in industrial production.

Genomic analyses reveal a low-temperature adapted clade in Halorubrum, a widespread haloarchaeon across global hypersaline environments.

BACKGROUND: Cold-adapted archaea have diverse ecological roles in a wide range of low-temperature environments. Improving our knowledge of the genomic features that enable psychrophiles to grow in cold environments helps us to understand their adaptive responses. However, samples from typical cold regions such as the remote Arctic and Antarctic are rare, and the limited number of high-quality genomes available leaves us with little data on genomic traits that are statistically associated with cold environmental conditions. RESULTS: In this study, we examined the haloarchaeal genus Halorubrum and defined a new clade that represents six isolates from polar and deep earth environments ('PD group' hereafter). The genomic G + C content and amino acid composition of this group distinguishes it from other Halorubrum and the trends are consistent with the established genomic optimization of psychrophiles. The cold adaptation of the PD group was further supported by observations of increased flexibility of proteins encoded across the genome and the findings of a growth test. CONCLUSIONS: The PD group Halorubrum exhibited denser genome packing, which confers higher metabolic potential with constant genome size, relative to the reference group, resulting in significant differences in carbon, nitrogen and sulfur metabolic patterns. The most marked feature was the enrichment of genes involved in sulfur cycling, especially the production of sulfite from organic sulfur-containing compounds. Our study provides an updated view of the genomic traits and metabolic potential of Halorubrum and expands the range of sources of cold-adapted haloarchaea.

Hly176B, a low-salt tolerant halolysin from the haloarchaeon Haloarchaeobius sp. FL176.

Extracellular proteases of haloarchaea can adapt to high concentrations of NaCl and can find useful applications in industrial or biotechnology processes where hypersaline conditions are desired. The diversity of extracellular proteases produced by haloarchaea is largely unknown though the genomes of many species have been sequenced and are publicly available. In this study, a gene encoding the extracellular protease Hly176B from the haloarchaeon Haloarchaeobius sp. FL176 was cloned and expressed in Escherichia coli. A related gene homolog to hly176B, hly176A, from the same strain was also expressed in E.coli, but did not show any proteinase activity after the same renaturation process. Therefore, we focus on the enzymatic properties of the Hly176B. The catalytic triad Asp-His-Ser was confirmed via site-directed mutagenesis, indicating that Hly176B belongs to the class of serine proteases (halolysin). Unlike previously reported extracellular proteases from haloarchaea, the Hly176B remained active for a relatively long time in an almost salt-free solution. In addition, the Hly176B displayed prominent tolerance to some metal ions, surfactants and organic solvents, and exerts its highest enzyme activity at 40 °C, pH 8.0 and 0.5 M NaCl. Therefore, this study enriches our knowledge of extracellular proteases and expands their applications for various industrial uses.

Efficacy and safety of sacubitril/allisartan for the treatment of primary hypertension: a phase 2 randomized, double-blind study.

This randomized, double-blind phase 2 study assessed the efficacy and safety of sacubitril/allisartan, an angiotensin receptor neprilysin inhibitor, compared with placebo in Chinese patients with mild to moderate hypertension. Eligible patients aged 18-75 years (n = 235) with mild to moderate hypertension were randomized to receive sacubitril/allisartan 120 mg (n = 52), sacubitril/allisartan 240 mg (n = 52), sacubitril/allisartan 480 mg (n = 52), placebo (n = 26) or olmesartan 20 mg (n = 53) once daily for 8 weeks. The primary end point was a reduction in clinic systolic blood pressure from baseline with different doses of sacubitril/allisartan versus placebo at 8 weeks. Secondary efficacy variables included clinic diastolic blood pressure and 24-h ambulatory blood pressure for the comparison between sacubitril/allisartan and placebo at 8 weeks. Safety assessments included all adverse events and serious adverse events. Sacubitril/allisartan 480 mg/day provided a significantly greater reduction in clinic systolic blood pressure than placebo at 8 weeks (between-treatment difference: -9.1 mmHg [95% confidence interval -1.6 to -16.6 mmHg], P = 0.02). There were also significant reductions in 24-h, daytime and nighttime systolic and diastolic blood pressure for sacubitril/allisartan 480 mg/day compared with placebo (P ≤ 0.03). Similarly, a greater reduction in daytime systolic blood pressure was observed for sacubitril/allisartan 240 mg/day compared with placebo (between-treatment difference: -7.3 mmHg [95% confidence interval -0.5 to -14.0 mmHg], P = 0.04). Sacubitril/allisartan was well tolerated, and no cases of angioedema were reported. Sacubitril/allisartan is effective for the treatment of hypertension in Chinese patients and is well tolerated.

Microbial community structure and shift pattern of industry brine after a long-term static storage in closed tank.

Brine from Dingyuan Salt Mine (Anhui, China), an athalassohaline hypersaline environment formed in the early tertiary Oligocene, is used to produce table salt for hundreds of millions of people. However, halophiles preserved in this niche during deposition are still unknown. Here, we employed cultivation and high-throughput sequencing strategies to uncover the microbial community and its shift after a long-term storage in the brine collected from Dingyuan Salt Mine. High-throughput sequencing showed (1) in the fresh brine (2021), Cyanobium_stocktickerPCC-6307 spp. (8.46%), Aeromonas spp. (6.91%) and Pseudomonas spp. (4.71%) are the dominant species in bacteria while Natronomonas spp. (18.89%), Halapricum spp. (13.73%), and Halomicrobium spp. (12.35%) in archaea; (2) after a 3-year-storage, Salinibacter spp. (30.01%) and Alcanivorax spp. (14.96%) surpassed Cyanobium_stocktickerPCC-6307 spp. (8.46%) becoming the dominant species in bacteria; Natronomonas spp. are still the dominant species, while Halorientalis spp. (14.80%) outnumbered Halapricum spp. becoming the dominant species in archaea; (3) Alcanivorax spp. and Halorientalis spp. two hydrocarbons degrading microorganisms were enriched in the brine containing hydrocarbons. Cultivation using hypersaline nutrient medium (20% NaCl) combined with high-throughput 16S rRNA gene sequencing showed that (1) the biomass significantly increased while the species diversity sharply declined after a 3-year-storage; (2) Halorubrum spp. scarcely detected from the environment total stocktickerDNA were flourishing after cultivation using AS-168 or NOM medium; (3) twelve possible new species were revealed based on almost full-length 16S rRNA gene sequence similarity search. This study generally uncovered the microbial community and the dominant halophiles in this inland athalassohaline salt mine, and provided a new insight on the shift pattern of dominant halophiles during a long-term storage, which illustrated the shaping of microorganisms in the unique environment, and the adaptation of microbe to the specific environment.

Genomic features of a new head-tail halovirus VOLN27B infecting a Halorubrum strain.

Relatively few viruses infecting haloarchaea (haloviruses) have been reported. In this study, the genome sequence of VOLN27B, a recently described archaeal tailed virus (arTV) with a myovirus morphotype was described, along with the sequence of its host, Halorubrum spp. LN27. Halovirus VOLN27B contains a linear, dsDNA genome of 76,891 bp which is predicted to encode 109 proteins and four tRNAs (tRNAThr, tRNAArg, tRNAGly and tRNAAsn). The DNA G + C content of VOLN27B genome is 56.1 mol%, nearly 10% lower than that of its host strain. A 315 bp LTR (long terminal repeat) was detected in the genome. The genome of its host strain LN27 was 3,301,211 bp (chromosome and 1 plasmid) with a DNA G + C content of 68.3 mol% and 3142 annotated protein coding genes. At least two hypothetical proviruses were detected in the genome. It lacked a CRISPR (Clustered Regularly Interspaced Short Palindromic Repeats) locus. Sequence similarity and phylogenetic tree reconstructions placed it within the genus Halorubrum as a potential new species. VOLN27B exhibits a distinct difference in the frequency of codon usage against its host strain Halorubrum sp. LN27. The organization of VOLN27B genome shows remarkable synteny and amino acid sequence similarity to the genomes and predicted proteins of HF1-like haloviruses (genus Haloferacalesvirus) and a provirus in the genome of Halorubrum depositum Y78. VOLN27B and its host Halorubrum sp. LN27 comprise a new virus-host system from a hypersaline ecosystem and can be used to further understand the novel biology at extreme salt concentration.

Halorhabdus amylolytica sp. nov. and Halorhabdus salina sp. nov., isolated from hypersaline environments.

Two novel extremely halophilic archaeal strains, designated H27T and FL145T, were isolated from a salt mine and a kelp salt sample, respectively. Cells of both strains were Gram-stain-negative, motile and pleomorphic. The 16S rRNA and rpoB' gene sequence similarities between strains H27T and FL145T were 96.60 and 88.77%. Strains H27T and FL145T were both closely related to Halorhabdus rudnickae WSM-64T, Halorhabdus tiamatea SARL4BT and Halorhabdus utahensis AX-2T, with a 16S rRNA gene sequence similarities of 98.14, 96.34 and 96.27% for strain H27T and 96.42, 95.82 and 96.17% for strain FL145T. The genome-based average nucleotide identity (ANI) values between strains H27T and FL145T, and these three species were 83.93, 79.79 and 79.09% (for strain H27T), and 78.32, 77.95 and 77.05% (for strain FL145T), respectively. The ANI value between strains H27T and FL145T was 78.65 %. The digital DNA-DNA hybridization values between strains H27T and FL145T, and these three species were less than 27.40%, which were below the recommended threshold for membership of the same species. The major polar lipids of both strains were found to consist of sulfated diglycosyl diether, triglycosyl diether, phosphatidylglycerol phosphate methyl ester and phosphatidylglycerol. The DNA G+C content was determined from genome to be 62.10 mol% for strain H27T and 61.51 mol% for strain FL145T. Based on phylogenetic, phenotypic, chemotaxonomic and genomic analyses, these two new isolates should be classified as representing two novel species in the genus Halorhabdus, with strain H27T (=CGMCC 1.16342T=NBRC 113589T) as the type strain of a new species for which we propose the name Halorhabdus amylolytica sp. nov., and strain FL145T (=CGMCC 1.13888T=NBRC 114260T) as the type strain of another new species for which we propose the name Halorhabdus salina sp. nov.

Increased Uric Acid, Gamma-Glutamyl Transpeptidase and Alkaline Phosphatase in Early-Pregnancy Associated With the Development of Gestational Hypertension and Preeclampsia.

Background: Previous studies have reported that biomarkers of liver injury and renal dysfunction were associated with hypertensive disorders of pregnancy (HDP). However, the associations of these biomarkers in early pregnancy with the risk of HDP and longitudinal blood pressure pattern during pregnancy were rarely investigated in prospective cohort studies. Methods: A total of 1,041 pregnant women were enrolled in this prospective cohort study. BP was assessed in four stages throughout pregnancy. The following biomarkers were measured at early pregnancy before 18 weeks gestation: lactate dehydrogenase (LDH), aspartate aminotransferase to alanine aminotransferase ratio (AST/ALT), gamma-glutamyl transpeptidase (GGT), alkaline phosphatase (ALP), uric acid (UA), and estimated glomerular filtration rate (eGFR). Linear mixed-effects and logistic regression models were used to examine the associations of these biomarkers with longitudinal BP pattern during pregnancy and HDP incidence, respectively. Results: In unadjusted models, higher serum UA, GGT, ALP, and LDH levels, as well as lower eGFR and AST/ALT, were associated with higher BP levels during pregnancy and an increased risk of HDP. After adjustment for maternal age, pre-pregnancy BMI and other potential confounders, UA, GGT, ALP, and LDH remained positively associated with both BP and HDP. However, eGFR and AST/ALT were not associated with HDP after adjusting for potential confounders. When including all 6 biomarkers simultaneously in multivariable analyses, increased UA, GGT, and ALP significantly associated with gestational hypertension and preeclampsia. Conclusion: This study suggests that increased UA, GGT, and ALP in early-pregnancy are independent risk factors of gestational hypertension and preeclampsia.

Comprehensive Characterization of Cachexia-Inducing Factors in Diffuse Large B-Cell Lymphoma Reveals a Molecular Subtype and a Prognosis-Related Signature.

BACKGROUND: Cachexia is defined as an involuntary decrease in body weight, which can increase the risk of death in cancer patients and reduce the quality of life. Cachexia-inducing factors (CIFs) have been reported in colorectal cancer and pancreatic adenocarcinoma, but their value in diffuse large B-cell lymphoma (DLBCL) requires further genetic research. METHODS: We used gene expression data from Gene Expression Omnibus to evaluate the expression landscape of 25 known CIFs in DLBCL patients and compared them with normal lymphoma tissues from two cohorts [GSE56315 (n = 88) and GSE12195 (n = 136)]. The mutational status of CIFs were also evaluated in The Cancer Genome Atlas database. Based on the expression profiles of 25 CIFs, a single exploratory dataset which was merged by the datasets of GSE10846 (n = 420) and GSE31312 (n = 498) were divided into two molecular subtypes by using the method of consensus clustering. Immune microenvironment between different subtypes were assessed via single-sample gene set enrichment analysis and the CIBERSORT algorithm. The treatment response of commonly used chemotherapeutic drugs was predicted and gene set variation analysis was utilized to reveal the divergence in activated pathways for distinct subtypes. A risk signature was derived by univariate Cox regression and LASSO regression in the merged dataset (n = 882), and two independent cohorts [GSE87371 (n = 221) and GSE32918 (n = 244)] were used for validation, respectively. RESULTS: Clustering analysis with CIFs further divided the cases into two molecular subtypes (cluster A and cluster B) associated with distinct prognosis, immunological landscape, chemosensitivity, and biological process. A risk-prognostic signature based on CCL2, CSF2, IL15, IL17A, IL4, TGFA, and TNFSF10 for DLBCL was developed, and significant differences in overall survival analysis were found between the low- and high-risk groups in the training dataset and another two independent validation datasets. Multivariate regression showed that the risk signature was an independently prognostic factor in contrast to other clinical characteristics. CONCLUSION: This study demonstrated that CIFs further contribute to the observed heterogeneity of DLBCL, and molecular classification and a risk signature based on CIFs are both promising tools for prognostic stratification, which may provide important clues for precision medicine and tumor-targeted therapy.

Halolysin R4 of Haloferax mediterranei confers its host antagonistic and defensive activities.

Halolysins, which are subtilisin-like serine proteases of haloarchaea, are usually secreted into the extracellular matrix via the twin-arginine translocation pathway. A small number of activated molecules can greatly affect cell growth owing to their proteolytic activity. It is, however, unclear as to whether this proteolysis-based growth inhibition by halolysins conveys antagonistic or defensive effects against other resident abd potentially competitive microorganisms. Here, we report that halolysin R4 (HlyR4), encoded by the hlyR4 gene, is the key enzyme in the initial steps of extracellular protein utilization in Haloferax mediterranei HlyR4 shows significant antagonistic activity against other haloarchaeal strains. Deletion of hlyR4 completely halts the inhibition activity of Hfx. mediterranei towards other haloarchaea, while correspondingly, complementation of hlyR4 almost completely restores the inhibition activity. Furthermore, Hfx. mediterranei strains containing hlyR4 showed a certain amount of resistance to halocins and halolysins in milieu, and this function of hlyR4 is reproducible in Haloarcula hispanica The versatility of HlyR4 enables its host to outcompete other haloarchaea living in the same hypersaline environment. Intriguingly, unlike the growth phase-dependent halolysins SptA and Nep, it is likely that HlyR4 may be secreted independent of growth phase. This study provides a new peptide antibiotics candidate in haloarchaea, as well as new insight towards a better understanding of the ecological roles of halolysins.Importance: This study shows that halolysin R4 from Haloferax mediterranei provides its host antagonistic and defensive activities against other haloarchaea, which expands our knowledge on the traditional function of haloarchaeal extracellular proteases. Haloarchaeal extracellular serine proteases have been previously discussed as growth-phase-dependent proteins, whereas our study reports constitutive expression of halolysin R4. This work also clearly reveals a hidden diversity of extracellular proteases from haloarchaea. Studies on multifunctional halolysins reveal that they play an important ecological role in shaping microbial community composition and provide a new perspective towards understanding the intricate interactions between haloarchaeal cells in hypersaline environments. HlyR4 can lyse competing cells living in the same environment, and the cell debris may probably be utilized as nutrients, which may constitute an important part of nutrient cycling in extremely hypersaline environments.

VOLN27B: A New Head-Tailed Halovirus Isolated from an Underground Salt Crystal and Infecting Halorubrum.

A novel halovirus, VOLN27B, was isolated from a drill core sample taken at a depth of approximately 430 m, from a layer formed during the Cretaceous period (Anhui, China). VOLN27B infects the halophilic archaeon Halorubrum sp. LN27 and has a head-tailed morphotype with a contractile tail, typical of myoviruses. The average head diameter is 64 ± 2.0 nm, and uncontracted tails are 15 ± 1.0 × 65 ± 2.0 nm. The latent period is about 10 h. The maturing time of VOLN27B in cells of Halorubrum sp. LN27 was nearly 8 h. The adsorption time of VOLN27B on cells of Halorubrum sp. LN27 was less than 1 min. Virus particles are unstable at pH values less than 5 or when the NaCl concentration is below 12% (w/v). VOLN27B and Halorubrum sp. LN27 were recovered from the same hypersaline environment and provide a new virus-host system in haloarchaea.

Factors Influencing the Mental Health of Firefighters in Shantou City, China.

BACKGROUND: Firefighters are routinely exposed to occupational stress and are therefore vulnerable to psychological problems. PATIENTS AND METHODS: This study assessed the prevalence of mental health symptoms and potential contributing factors in a sample of firefighters in Shantou city, in the Guangdong Province of China. We conducted a cross-sectional survey with 335 firefighters, including 329 male and 6 female firefighters. We used a questionnaire which assessed anxiety and depression, as indicated by the Zung Self-Rating Anxiety Scale (SAS) and Self-Rating Depression Scale (SDS), as well as other mental health symptoms, using the Symptom Checklist-90 (SCL-90). Basic information and potential-related factors were also collected. RESULTS: The average age of participants was 27.38 (SD ± 6.11) years. Assessed by the indexed score of different scales, SAS and SDS positive screening rates were 6.86% and 22.68%, respectively. SCL-90 scores indicated that 6.86% of participants had mental health symptoms. Logistic regression analysis showed that educational level, firefighter rank, and birth order were associated with mental health outcomes. Firefighters in Shantou were also shown to have better mental health outcomes than the Chinese military, but worse than the national population of firefighters. CONCLUSION: These findings indicated the mental health of firefighters is not good. It is necessary to explore effective approaches to help preventing and treating mental disorder in firefighters.

Halomicroarcula amylolytica sp. nov., a novel halophilic archaeon isolated from a salt mine.

A halophilic archaeon named strain LR21T was isolated from a salt mine in Yunnan Province, PR China. Cells were spherical, Gram-stain-negative and motile. Strain LR21T grew at 20-50 °C (optimum, 42 °C), with 8-30 % (w/v) NaCl (optimum, 23 %) and at pH 5.5-9.5 (optimum, pH 7.5-8.5). Mg2+ was not required for growth. The major polar lipid profile comprised phosphatidylglycerol, phosphatidylglycerol phosphate methyl ester and phosphatidylglycerol sulfate. Strain LR21T had two dissimilar 16S rRNA genes (rrnA and rrnB) and they were closely related to Halomicroarcula limicola YGHS32T, Hma. pellucida BNERC31T and Hma. salina YGHS18T with sequence similarities of 95.3-99.0, 93.0-96.2 and 93.2-95.9 %, respectively, and much lower values to other members. The rpoB' gene sequence similarities between strain LR21T and Hma. limicola YGHS32T, Hma. pellucida BNERC31T and Hma. salina YGHS18T were 95.2, 91.2 and 91.2 % respectively. The values of average nucleotide identity (ANI) and average amino-acid identity (AAI) between strain LR21T and Hma. limicola YGHS32T, were 89.0 and 90.1 %, respectively. DNA relatedness between strains LR21T and Hma. limicola YGHS32T determined by in silico DNA-DNA hybridization was 36.8 %. Values of ANI and AAI between strain LR21T and other members in the genus Halomicroarcula were far below 95 % and the DNA-DNA relatedness values between strain LR21T and its close relatives were much lower than 70 %, which is far below the boundary for delineation of a new species prokaryote. The DNA G+C content of strain LR21T was 62.0 mol% (genome). The results suggested that strain LR21T represents a novel species of the genus Halomicroarcula, for which the name Halomicroarcula amylolytica sp. nov. is proposed. The type strain is LR21T (=CGMCC 1.13611T=NBRC 113588T).

Structural asymmetry does not indicate hemiphosphorylation in the bacterial histidine kinase CpxA.

Histidine protein kinases (HKs) are prevalent prokaryotic sensor kinases that are central to phosphotransfer in two-component signal transduction systems, regulating phosphorylation of response regulator proteins that determine the output responses. HKs typically exist as dimers and can potentially autophosphorylate at each conserved histidine residue in the individual protomers, leading to diphosphorylation. However, analyses of HK phosphorylation in biochemical assays in vitro suggest negative cooperativity, whereby phosphorylation in one protomer of the dimer inhibits phosphorylation in the second protomer, leading to ∼50% phosphorylation of the available sites in dimers. This negative cooperativity is often correlated with an asymmetric domain arrangement, a common structural characteristic of autophosphorylation states in many HK structures. In this study, we engineered covalent dimers of the cytoplasmic domains of Escherichia coli CpxA, enabling us to quantify individual species: unphosphorylated, monophosphorylated, and diphosphorylated dimers. Together with mathematical modeling, we unambiguously demonstrate no cooperativity in autophosphorylation of CpxA despite its asymmetric structures, indicating that these asymmetric domain arrangements are not linked to negative cooperativity and hemiphosphorylation. Furthermore, the modeling indicated that many parameters, most notably minor amounts of ADP generated during autophosphorylation reactions or present in ATP preparations, can produce ∼50% total phosphorylation that may be mistakenly attributed to negative cooperativity. This study also establishes that the engineered covalent heterodimer provides a robust experimental system for investigating cooperativity in HK autophosphorylation and offers a useful tool for testing how symmetric or asymmetric structural features influence HK functions.

Geographical Isolation, Buried Depth, and Physicochemical Traits Drive the Variation of Species Diversity and Prokaryotic Community in Three Typical Hypersaline Environments.

The prokaryotic community composition, species diversity and the distribution patterns at various taxonomic levels in a salt lake (Chaka salt lake), solar salterns (Taipei saltworks and Dongfang saltworks), and salt mines (Yuanyongjing salt mine, Xiangyan salt mine, and Dinyuan salt mine) were investigated using clone library or Illumina MiSeq sequencing. The clone library approach revealed that the salt lake harbors low species diversity (H' = 0.98) as compared to the solar saltern (H' = 4.36) and salt mine (H' = 3.57). The dominant group in the salt lake is a species from the genus Haloparvum which constitutes about 85% of the total sequences analyzed. The species diversities in salt salterns and salt mines are richer than in the salt lake, and the dominant group is less significant in terms of total percentage. High-throughput sequencing showed that geographical isolation greatly impacted on the microbial community (phyla level) and species diversity (operational taxonomic units (OTUs) level) of salt mines. Species of the genus Natronomonas are found in all three types of environments investigated. In addition, the microbial community and species diversity of different stratums of the salt mine are very similar. Furthermore, species of the genus Halorubrum flourish in the newest stratum of salt mine and have become the dominant group. This study provides some new knowledge on the species diversity and prokaryotic community composition of three typical hypersaline environments.

Halomicrococcus hydrotolerans gen. nov., sp. nov., an extremely halophilic archaeon isolated from a subterranean salt deposit.

A halophilic archaeon, strain H22T, was isolated from a subterranean salt deposit sampled at Yunnan salt mine, PR China. Colonies of strain H22T were light pink-pigmented. Cells were coccus, non-motile, Gram-stain-negative, and did not lyse in distilled water. The strain was aerobic and grew at 20-55 °C (optimum, 37 °C), in the presence of 10-30 % (w/v) NaCl (20 %) and at pH 6.5-9.0 (pH 7.0). Mg2+ was required for growth (optimum, 0.005 M). Major polar lipids were phosphatidylglycerol, phosphatidylglycerol phosphate methyl ester and sulfated mannosyl-glucosyl-glycerol diether-1. Sequence similarity search based on the multiple 16S rRNA genes (rrnA, rrnB and rrnC) of strain H22T revealed that it was most closely related to species of the genera Haloarchaeobius, Haladaptatus, Halorussus and Halorubellus with relative low sequence similarities (91.9-93.7 %). The strain, however, shared highest rpoB' gene sequence identities with Halorussus rarus TBN4T (90.8 % rpoB' gene sequence similarity). Phylogenetic trees based on 16S rRNA and rpoB' gene sequences revealed a robust lineage of the strain H22T with members of related genera of the family Halobacteriaceae. The DNA G+C content of strain H22T was 62.9 mol%. Genome-based analysis of average nucleotide identity (ANI) and in silico DNA-DNA hybridization (DDH) between strains H22T and its closest relative were equal or lower than 77.7 and 22.4 %, respectively, which were far below the threshold for delineation of a new species. Based on ANI values, in silico DDH, and distinct morphological and physiological differences from the previously described taxa, we suggest that strain H22T represents a novel species of a new genus within the family Halobacteriaceae, for which the name Halomicrococcus hydrotolerans gen. nov., sp. nov. is proposed. The type strain is H22T (=CGMCC 1.16291T=NBRC 113231T).