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Microalgae are photosynthetic organisms with potentials in sustainable production of valuable metabolites such as polyunsaturated oil. Low nitrogen cultivation is widely used for induction of microalgal oil production. Previously we found that low inorganic nitrogen (low N, 4.5 mM NaNO3) favored oil production in a dryland-isolated eustigmatophyte microalga Vischeria sp. WL1, relative to the usually used nitrogen level (18 mM NaNO3), while low organic nitrogen (low pepN, 4.5 mM peptone) led to both rapider growth and higher oil yield than low N. Here we analyzed the lipidome profiles of Vischeria sp. WL1 under low N and low pepN conditions. Our results revealed that the lipidome profiles induced by both conditions were apparently different. Overall, low N had a much weaker impact on the lipidome profile than low pepN. Notably, low N uniquely induced a significant increase of phosphatidylinositol (PI), phosphatidylinositol phosphate (PIP), phosphatidylinositol bisphosphate (PIP2) and phosphatidylinositol trisphosphate (PIP3), whereas low pepN induced a significant increase of phosphatidylcholine (PC) and phosphatidylethanolamine (PE). In addition, low pepN induced a significant increase of neutral glycerolipids. This research deepens our understanding on the lipid metabolism of Vischeria sp. WL1 under different nitrogen conditions and could also guide oil production strategy in microalgae by adopting suitable nitrogen resources. [ABSTRACT FROM AUTHOR]

Halophilic Archaea are widely distributed globally in hypersaline environments. However, little is known of how dominant halophilic archaeal genera are distributed across environments and how they may co-associate across ecosystems. Here, the archaeal community composition and diversity from hypersaline environments (> 300 g/L salinity; total of 33 samples) in the Qaidam Basin of China were investigated using high-throughput Illumina sequencing of 16S rRNA genes. The archaeal communities (total of 3,419 OTUs) were dominated by the class Halobacteria (31.7–99.6% relative abundances) within the phylum Euryarchaeota (90.8–99.9%). Five predominant taxa, including Halorubrum, Halobacterium, Halopenitus, Methanothrix, and Halomicrobium, were observed across most samples. However, several distinct genera were associated with individual samples and were inconsistently distributed across samples, which contrast with previous studies of hypersaline archaeal communities. Additionally, co-occurrence network analysis indicated that five network clusters were present and potentially reflective of interspecies interactions among the environments, including three clusters (clusters II, III, and IV) comprising halophilic archaeal taxa within the Halobacteriaceae and Haloferacaceae families. In addition, two other clusters (clusters I and V) were identified that comprised methanogens. Finally, salinity comprising ionic concentrations (in the order of Na+ > Ca2+ > Mg2+) and pH were most correlated with taxonomic distributions across sample sites. [ABSTRACT FROM AUTHOR]

Hypersaline lakes and saltern areas are important industrial and biodiversity resources in the Qaidam Basin of China that reside at > 2600 m asl. Most hypersaline environments in this area are characterized by saturated salinity (~ 300 g/L salinity), nearly neutral pH, intense ultraviolet radiation, and extremely variable temperature fluctuations. The core bacterial communities associated with these stressful environments have nevertheless remained uninvestigated. 16S rRNA gene Illumina sequencing analyses revealed that the bacterial communities were dominated by core lineages including the Proteobacteria (39.4–64.6%) and the Firmicutes (17.0–42.7%). However, the relative abundances of common lineages, and especially the five most abundant taxa of Pseudomonas, Lactococcus, Anoxybacillus, Acinetobacter, and Brevundimonas, were highly variable across communities and closely associated with hypersaline characteristics in the samples. Network analysis revealed the presence of co-occurrence high relative abundance taxa (cluster I) that were highly correlated across all hypersaline samples. Additionally, temperature, total organic carbon, K+, and Mg2+ correlated highest with taxonomic distributions across communities. These results highlight the potential mechanisms that could underlie survival and adaptation to these extreme hypersaline ecosystems. [ABSTRACT FROM AUTHOR]

Seasonal temperature-fluctuation has been regarded as a key environmental factor affecting rural biogas fermentation yields. The present study investigated the impact of seasonal temperature-fluctuation on operating-temperatures and biogas production in rural household digesters at Qinghai Plateau and revealed the related changes in microbial diversity and community structure by 16S rRNA gene high-throughput sequencing (HTS) analysis. Our results showed closely positive correlation between operating-temperatures and biogas production. HTS analysis indicated the highest diversity for bacteria community in autumn (at highest operating-temperatures) and late winter (at lowest operating-temperatures) and for archaea community only in autumn. HTS analysis classified bacteria into 21 phyla and 346 genera with the most predominant phyla Firmicutes, Bacteroidetes and Proteobacteria (> 72.4% in total) and the most predominant genera Proteiniphilum, Clostridium sensustricto 1, Petrimonas, Pseudomonas and Fastidiosipila (37.09–38.61% in total). HTS analysis also revealed two main archaea orders (Methanomicrobiales and Methanobacteriales) and one predominant genus Methanogenium to support plateau biogas fermentation. Especially, a remarkable impact of temperature on the community abundances of bacteria phyla Synergistetes and archaea genera Methanogenium and Thermogymnomonas was observed, and such microbial community structure changes were positively consistent with the biogas production. The present work provided the first set of evidences to link temperature-controlled modulation of microbial community structure with rural household biogas production at Qinghai Plateau. [ABSTRACT FROM AUTHOR]

Background: Esophageal cancer (EC) is the leading cause of cancer‐related mortality worldwide. The underlying genetic risk factors remain unclear. The association between gene growth hormone receptor (GHR) and phospholipase C epsilon 1 (PLCE1) polymorphisms and the EC risk were identified in this study. Methods: A total of 506 EC cases and 507 controls were included in this research. Two SNPs (rs6898743 of GHR and rs2274223 of PLCE1) were selected and genotyped. The associations between gene polymorphisms and the EC risk were assessed by logistic regression analysis. The databases RegulomeDB, GTEx, and UALCAN were used for functional annotations. Results: In the allelic frequencies analysis, the rs6898743 of GHR was associated with decreased susceptibility of EC (OR = 0.83, 95% CI: 0.70–1.00, p = 0.049), while rs2274223 of PLCE1 was associated with increased 0.25‐fold EC risk (OR = 1.25, 95% CI: 1.02–1.53, p = 0.037). The "GC" genotype of rs6898743 was associated with a 0.24‐fold decreased risk of EC under co‐dominant model (OR = 0.76, 95% CI: 0.58–0.99, p = 0.046), and the "GA" genotype of rs2274223 was associated with increased EC risk under co‐dominant model (OR = 1.36, 95% CI: 1.04–1.77, p = 0.023). Using GTEx database, rs2274223 was found to be significant associated with increased PLCE1 expression (p = 4.1 × 10−7) in esophagus muscularis. The UALCAN database demonstrated that the GHR gene was under‐expressed in esophageal cancer tissues (p = 0.017). Conclusion: The gene GHR and PLCE1 polymorphisms are associated with EC in the general population and the results need to be verified in future. [ABSTRACT FROM AUTHOR]

Ectoine has gained considerable attention as a high-value chemical with significant application potential and market demand. This study aimed to increase ectoine yields by blocking the metabolic shunt pathway of l-aspartate-4-semialdehyde, the precursor substrate in ectoine synthesis. The homoserine dehydrogenase encoded by hom in H. campaniensis strain XH26 is responsible for the metabolic shunt of l-aspartate-4-semialdehyde to glycine. CRISPR/Cas9 technology was used to seamlessly knockout hom, blocking the metabolic shunt pathway to increase ectoine yields. The ectoine yield of XH26/Δhom was 351.13 mg (g CDW)−1 after 48 h of incubation in 500 mL shake flasks using optimal medium with 1.5 mol L−1 NaCl, which was significantly higher than the 239.18 mg (g CDW)−1 of the wild-type strain. Additionally, the absence of the ectoine metabolic shunt pathway affects betaine synthesis, and thus the betaine yields of XH26/Δhom was 19.98 mg (g CDW)−1, considerably lower than the 69.58 mg (g CDW)−1 of the wild-type strain. Batch fermentation parameters were optimized, and the wild-type strain and XH26/Δhom were fermented in 3 L fermenters, resulting in a high ectoine yield of 587.09 mg (g CDW)−1 for the defective strain, which was significantly greater than the ectoine yield of 385.03 mg (g CDW)−1 of the wild-type strain. This study showed that blocking the metabolic shunt of synthetic substrates effectively increases ectoine production, and a reduction in the competitively compatible solute betaine appears to promote increased ectoine synthesis. [ABSTRACT FROM AUTHOR]

A new strain of Eustigmatophyceae, Vischeria sp. WL1, which accumulates oil droplets in the cells, was isolated from a large biological soil crust in the arid steppes of north-western China. Its growth and oil productivity were explored using nitrate–N and peptone-N sources, as well as salt stress treatment. Compared to the commonly used ~ 18.0 mM nitrate–N, 4.5 mM nitrate–N was found to be relatively cost-effective for oil production, and 4.5 mM peptone-N was much more effective. After 24 days of cultivation, the biomass increased up to 7.5 times the initial biomass and the oil yield reached 1.13 g L−1 for the 4.5 mM peptone-N condition. In addition, supplementation of 0.3 M NaCl in the medium was found to enhance the oil productivity, while 3.0 M NaCl treatment facilitated the obtaining of relatively pure oil, removing more than 95% of the cellular pigments prior to oil extraction. The oils produced are characterized by high contents of C16:1 (~ 50%) and C20:5 (~ 10%) fatty acids, implying that they may serve as ideal biodiesel feedstocks or nutritional supplements. In general, this study reported a new dryland microalgal strain and its biotechnological potential in the production of oils with biofuel or edible value. [ABSTRACT FROM AUTHOR]

Halophilic bacteria such as the genus Halomonas are promising candidates in diverse industrial, agricultural and biomedical applications. Here, we successfully isolated a halophilic Halomonas alkaliphila strain XH26 from Xiaochaidan Salt Lake, and studied its osmoadaptation strategies using transcriptome and ectoine analysis. Divergent mechanisms were involved in osmoadaptation at different salinities in H. alkaliphila XH26. At moderate salinity (6% NaCl), increased transcriptions of ABC transporters related to iron (III), phosphate, phosphonate, monosaccharide and oligosaccharide import were observed. At high salinity (15% NaCl), transcriptions of flagellum assembly and cell motility were significantly inhibited. The transcriptional levels of ABC transporter genes related to iron (III) and iron3+-hydroxamate import, glycine betaine and putrescine uptake, and cytochrome biogenesis and assembly were significantly up-regulated. Ectoine synthesis and accumulation was significantly increased under salt stress, and the increased transcriptional expressions of ectoine synthesis genes ectB and ectC may play a key role in high salinity induced osmoadaptation. At extreme high salinity (18% NaCl), 5-hydroxyectoine and ectoine worked together to maintain cell survival. Together these results give valuable insights into the osmoadaptation mechanisms of H. alkaliphila XH26, and provide useful information for further engineering this specific strain for increased ectoine synthesis and related applications. [ABSTRACT FROM AUTHOR]

Puma Yumco Lake (PYL) is an ultraoligotrophic freshwater lake that sits an altitude of 5030 m within the Qinghai-Tibet Plateau of China. The bacterial and archaeal diversity of the lake remains poorly understood, despite their potential to inform on biogeochemical cycling and environment-microbial associations in these unique environments. Here, the bacterial and archaeal communities of PYL were investigated using high-throughput sequencing analysis of community 16S rRNA gene sequences. Further, the relationships among dominant taxa and environmental factors were comprehensively evaluated. Bacterial diversity comprised 31 phyla and 371 genera (10,645 operational taxonomic units [OTUs], Shannon index values of 5.21–6.16) and was significantly higher than that of Archaea (five phyla and 24 genera comprising 1141 OTUs and Shannon index values of 1.18–3.28). The bacterial communities were dominated by Proteobacteria (48.42–59.97% relative abundances), followed by Bacteroidetes (12.5–32.51%), Acidobacteria (2.07–11.56%), Firmicutes (0.65–6.32%), Planctomycetes (0.99–3.56%), Gemmatimonadetes (0.38–3.57%), Actinobacteria (1.67–3.52%), Verrucomicrobia (0.87–2.01%), and Chloroflexi (0.5–1.17%). In addition, archaeal communities were dominated by Thaumarchaeota (33.22–93.00%), followed by Euryarchaeota (2.89–35.47%), Woesearchaeota (0.99–31.04%), and Pacearchaeota (0.01–1.14%). The most abundant bacterial genus was Rhodoferax (5.73–26.62%) and the most abundant archaeal genus was the ammonia-oxidizing Nitrososphaera (29.18–91.46%). These results suggest that the Rhodoferax and Nitrososphaera are likely to participate in biogeochemical cycles in these environments through photoheterotrophy and nitrification, respectively. Taken together, these results provide valuable data for better understanding microbial interactions with each other and with these unique environments. [ABSTRACT FROM AUTHOR]

To investigate contribution of environmental factor(s) to microbial community structure(s) involved in rural household biogas fermentation at Qinghai Plateau, we collected slurry samples from 15 digesters, with low-temperature working conditions (11.1-15.7 °C) and evenly distributed at three counties (Datong, Huangyuan, and Ledu) with cold plateau climate, to perform polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE) and further sequencing. The bacterial communities in the total 15 digesters were classified into 38 genera with Mangroviflexus (12.1%) as the first dominant, and the archaeal communities into ten genera with Methanogenium (38.5%) as the most dominant. For each county, the digesters with higher biogas production, designated as HP digesters, exclusively had 1.6-3.1 °C higher fermentation temperature and the unique bacterial structure composition related, i.e., unclassified Clostridiales for all the HP digesters and unclassified Marinilabiliaceae and Proteiniclasticum for Ledu HP digesters. Regarding archaeal structure composition, Methanogenium exhibited significantly higher abundances at all the HP digesters and Thermogymnomonas was the unique species only identified at Ledu HP digesters with higher-temperature conditions. Redundancy analysis also confirmed the most important contribution of temperature to the microbial community structures investigated. This report emphasized the correlation between temperature and specific microbial community structure(s) that would benefit biogas production of rural household digesters at Qinghai Plateau. [ABSTRACT FROM AUTHOR]

Keke Salt Lake is located in the Qaidamu Basin of China. It is a unique magnesium sulfate-subtype hypersaline lake that exhibits a halite domain ecosystem, yet its microbial diversity has remained unstudied. Here, the microbial community structure and diversity was investigated via high-throughput sequencing of the V3-V5 regions of 16S rRNA genes. A high diversity of operational taxonomic units was detected for Bacteria and Archaea (734 and 747, respectively), comprising 21 phyla, 43 classes, and 201 genera of Bacteria and 4 phyla, 4 classes, and 39 genera of Archaea. Salt-saturated samples were dominated by the bacterial genera Bacillus (51.52%-58.35% relative abundance), Lactococcus (9.52%-10.51%), and Oceanobacillus (8.82%-9.88%) within the Firmicutes phylum (74.81%-80.99%), contrasting with other hypersaline lakes. The dominant Archaea belonged to the Halobacteriaceae family, and in particular, the genera (with an abundance of >10% of communities) Halonotius, Halorubellus, Halapricum, Halorubrum, and Natronomonas. Additionally, we report the presence of Nanohaloarchaeota and Woesearchaeota in Qinghai-Tibet Plateau lakes, which has not been previously documented. Total salinity (especially Mg2+, Cl-, Na+, and K+) mostly correlated with taxonomic distribution across samples. These results expand our understanding of microbial resource utilization within hypersaline lakes and the potential adaptations of dominant microorganisms that allow them to inhabit such environments. [ABSTRACT FROM AUTHOR]