Isolation and characterization of a Halomonas species for non-axenic growth-associated production of bio-polyesters from sustainable feedstocks.

Biodegradable plastics are urgently needed to replace petroleum-derived polymeric materials and prevent their accumulation in the environment. To this end, we isolated and characterized a halophilic and alkaliphilic bacterium from the Great Salt Lake in Utah. The isolate was identified as a Halomonas species and designated "CUBES01." Full-genome sequencing and genomic reconstruction revealed the unique genetic traits and metabolic capabilities of the strain, including the common polyhydroxyalkanoate (PHA) biosynthesis pathway. Fluorescence staining identified intracellular polyester granules that accumulated predominantly during the strain's exponential growth, a feature rarely found among natural PHA producers. CUBES01 was found to metabolize a range of renewable carbon feedstocks, including glucosamine and acetyl-glucosamine, as well as sucrose, glucose, fructose, and further glycerol, propionate, and acetate. Depending on the substrate, the strain accumulated up to ~60% of its biomass (dry wt/wt) in poly(3-hydroxybutyrate), while reaching a doubling time of 1.7 h at 30°C and an optimum osmolarity of 1 M sodium chloride and a pH of 8.8. The physiological preferences of the strain may not only enable long-term aseptic cultivation but also facilitate the release of intracellular products through osmolysis. The development of a minimal medium also allowed the estimation of maximum polyhydroxybutyrate production rates, which were projected to exceed 5 g/h. Finally, also, the genetic tractability of the strain was assessed in conjugation experiments: two orthogonal plasmid vectors were stable in the heterologous host, thereby opening the possibility of genetic engineering through the introduction of foreign genes. IMPORTANCE: The urgent need for renewable replacements for synthetic materials may be addressed through microbial biotechnology. To simplify the large-scale implementation of such bio-processes, robust cell factories that can utilize sustainable and widely available feedstocks are pivotal. To this end, non-axenic growth-associated production could reduce operational costs and enhance biomass productivity, thereby improving commercial competitiveness. Another major cost factor is downstream processing, especially in the case of intracellular products, such as bio-polyesters. Simplified cell-lysis strategies could also further improve economic viability.

The polyextremophile Natranaerobius thermophilus adopts a dual adaptive strategy to long-term salinity stress, simultaneously accumulating compatible solutes and K.

The bacterium Natranaerobius thermophilus is an extremely halophilic alkalithermophile that can thrive under conditions of high salinity (3.3-3.9 M Na+), alkaline pH (9.5), and elevated temperature (53°C). To understand the molecular mechanisms of salt adaptation in N. thermophilus, it is essential to investigate the protein, mRNA, and key metabolite levels on a molecular basis. Based on proteome profiling of N. thermophilus under 3.1, 3.7, and 4.3 M Na+ conditions compared to 2.5 M Na+ condition, we discovered that a hybrid strategy, combining the "compatible solute" and "salt-in" mechanisms, was utilized for osmotic adjustment dur ing the long-term salinity adaptation of N. thermophilus. The mRNA level of key proteins and the intracellular content of compatible solutes and K+ support this conclusion. Specifically, N. thermophilus employs the glycine betaine ABC transporters (Opu and ProU families), Na+/solute symporters (SSS family), and glutamate and proline synthesis pathways to adapt to high salinity. The intracellular content of compatible solutes, including glycine betaine, glutamate, and proline, increases with rising salinity levels in N. thermophilus. Additionally, the upregulation of Na+/ K+/ H+ transporters facilitates the maintenance of intracellular K+ concentration, ensuring cellular ion homeostasis under varying salinities. Furthermore, N. thermophilus exhibits cytoplasmic acidification in response to high Na+ concentrations. The median isoelectric points of the upregulated proteins decrease with increasing salinity. Amino acid metabolism, carbohydrate and energy metabolism, membrane transport, and bacterial chemotaxis activities contribute to the adaptability of N. thermophilus under high salt stress. This study provides new data that support further elucidating the complex adaptation mechanisms of N. thermophilus under multiple extremes.IMPORTANCEThis study represents the first report of simultaneous utilization of two salt adaptation mechanisms within the Clostridia class in response to long-term salinity stress.

Novel genomic and phenotypic traits of polyhydroxyalkanoate-producing bacterium ZZQ-149, the type strain of Halomonas qinghailakensis.

BACKGROUND: Polyhydroxyalkanoates (PHAs) are optimal potential materials for industrial and medical uses, characterized by exceptional sustainability, biodegradability, and biocompatibility. These are primarily from various bacteria and archaea. Bacterial strains with effective PHA formation capabilities and minimal production cost form the foundation for PHA production. Detailed genomic analysis of these PHA-generating bacteria is vital to understand their PHA production pathways and enhance their synthesis capability. RESULTS: ZZQ-149, a halophilic, PHA-producing bacterium, was isolated from the sediment of China's Qinghai Lake. Here, we decoded the full genome of ZZQ-149 using Single Molecule Real Time (SMRT) technology based on PacBio RS II platform, coupled with Illumina sequencing platforms. Physiological, chemotaxonomic traits, and phylogenetic analysis based on 16 S rRNA gene and single copy core genes of ninety-nine Halomonas type strains identified ZZQ-149 as the type strain of Halomonas qinghailakensis. Furthermore, a low average nucleotide identity (ANI, < 95%) delineated the genetic differences between ZZQ-149 and other Halomonas species. The ZZQ-149 genome, with a DNA G + C content of 52%, comprises a chromosome (3, 798, 069 bps) and a plasmid (6, 107 bps). The latter encodes the toxin-antitoxin system, BrnT/BrnA. Through comprehensive genome sequencing and analysis, we identified multiple PHA-synthesizing enzymes and an unprecedented combination of eight PHA-synthesizing pathways in ZZQ-149. CONCLUSIONS: Being a halophilic, PHA-producing bacterium, ZZQ-149 exhibits potential as a high PHA producer for engineered bacteria via genome editing while ensuring low-cost PHA production through continuous, unsterilized fermentation.

Phylogenetic assessment of the halophilic Australian gastropod Coxiella and South African Tomichia resolves taxonomic uncertainties, uncovers new species and supports a Gondwanan link.

Genetic and morphological data have suggested a Gondwanan connection between the three non-marine aquatic gastropod genera Coxiella Smith, 1894, Tomichia Benson, 1851 and Idiopyrgus Pilsbry, 1911. These genera have recently been included in the family Tomichiidae Wenz, 1938, however, further assessment of the validity of this family is warranted. Coxiella is an obligate halophile that occurs in Australian salt lakes while Tomichia occurs in saline and freshwater environments in southern Africa and Idiopyrgus is a freshwater taxon from South America. Despite their novel evolutionary and ecological characteristics, Coxiella, Tomichia and Idiopyrgus are poorly studied, and the lack of a contemporary taxonomic framework restricts our ability to assess the risk of declining habitat quality to these gastropods. We used data from mitochondrial (COI and 16S) and nuclear (28S and 18S) genes in 20 species from all three genera to undertake the most comprehensive phylogenetic test of the Tomichiidae to date. Bayesian and Maximum Likelihood phylogenetic analyses of a concatenated dataset (2974 bp) of all four genes strongly supported a monophyletic Tomichiidae. The COI analysis (n = 307) identified 14 reciprocally monophyletic lineages in Coxiella that comprised eight of the nine currently described species and at least six putative new species. Four distinct genetic clades of species with somewhat distinctive morphologies were found, each of which may constitute a distinct genera. In addition, four species of Tomichia were identified, including three described and one putatively new species. Current species descriptions of Coxiella do not account for the range of morphological variation observed within most described species, and although morphology is reasonably effective at delineating between clades, it is of limited use when trying to separate closely related Coxiella species. The improved understanding of the taxonomy and diversity of Tomichia and especially Coxiella will underpin future studies and conservation planning for these taxa.

Draft genome sequence of Hahella sp. CR1 and its ability in producing cellulases for saccharifying agricultural biomass.

Hahella is a genus that has not been well-studied, with only two identified species. The potential of this genus to produce cellulases is yet to be fully explored. The present study isolated Hahella sp. CR1 from mangrove soil in Tanjung Piai National Park, Malaysia, and performed whole genome sequencing (WGS) using NovaSeq 6000. The final assembled genome consists of 62 contigs, 7,106,771 bp, a GC ratio of 53.5%, and encoded for 6,397 genes. The CR1 strain exhibited the highest similarity with Hahella sp. HN01 compared to other available genomes, where the ANI, dDDH, AAI, and POCP were 97.04%, 75.2%, 97.95%, and 91.0%, respectively. In addition, the CAZymes analysis identified 88 GTs, 54 GHs, 11 CEs, 7 AAs, 2 PLs, and 48 CBMs in the genome of strain CR1. Among these proteins, 11 are related to cellulose degradation. The cellulases produced from strain CR1 were characterized and demonstrated optimal activity at 60 ℃, pH 7.0, and 15% (w/v) sodium chloride. The enzyme was activated by K+, Fe2+, Mg2+, Co2+, and Tween 40. Furthermore, cellulases from strain CR1 improved the saccharification efficiency of a commercial cellulase blend on the tested agricultural wastes, including empty fruit bunch, coconut husk, and sugarcane bagasse. This study provides new insights into the cellulases produced by strain CR1 and their potential to be used in lignocellulosic biomass pre-treatment.

Lipingzhangella rawalii sp. nov., a novel halophile isolated from Sambhar Salt Lake, Rajasthan, India.

A haloalkaliphilic actinobacterial strain LS1_29T, isolated from an inland hypersaline Sambhar Salt Lake, situated in Rajasthan, India, was subjected to taxonomic characterisation using the polyphasic approach. Cells of the strain were Gram stain positive and aerobic, having reticulate and aerial hyphae. The major fatty acids detected were iso C16:0 (38.23%), anteiso C17:0 (20.52%), iso C18:0 10 methyl (8.09%), iso C18:0 (7.74%) and iso C17:0 (7.48%). The major polar lipids identified were diphosphatidyl glycerol, phosphatidylglycerol, phosphatidylcholine and phospholipids. Phylogenetic analysis based on the 16S rRNA gene sequence indicated that the strain belonged to the genus Lipingzhangella with the highest similarity of 94.09% to Lipingzhangella halophila EGI 80537 T and formed a separate clade within the genus Lipingzhangella. The DNA G + C content of genomic DNA of strain LS1_29T was 67.99 mol%. The strain showed the highest orthologous average nucleotide identity (OrthoANI) value of 72.80% and digital DNA-DNA hybridization (dDDH) value of 20.3% with Lipingzhangella halophila EGI 80537 T. Based on the phenotypic, chemotaxonomic and phylogenetic characteristics, strain LS1_29T represents a novel species within the genus Lipingzhangella, for which the name Lipingzhangella rawalii sp. nov. is proposed. The type strain of the type species is LS1_29T (= KCTC 49199 T = JCM 32979 T = MCC 3420 T).

Halorubrum hochsteinianum sp. nov., an ancient haloarchaeon from a natural experiment.

A single extremely halophilic strain was isolated from salt brine produced when a fresh water lake flooded a large salt mine located beneath the lake. The water that entered this mine contained less than 0.34 M NaCl, but over time, this sealed brine became saturated by Cenozoic age salt (121-125 million-year BCE). The isolated strain requires at least 1.7 M NaCl for survival and grows optimally in 3.1 M NaCl. Therefore, it could not have survived or been present in the waters that flooded this salt mine. The strain grows at a pH range from 6.5 to 9.0 and has a wide tolerance to temperatures from 25 ℃ to at least 60 ℃. The comparison of 16S rRNA and rpoB' genes revealed that strain 1-13-28T is related to Halorubrum tebenquichense DSM 14210T showing 98.6% and 98.1% similarities, respectively. Phylogenetic analyses based on 16S rRNA, rpoB' genes and 122 concatenated archaeal genes show that the strain 1-13-28T consistently forms a cluster with Halorubrum tebenquichense of the genus Halorubrum. Strain 1-13-28T contained sulfated mannosyl glucosyl diether, and the polar lipid profile was identical to those of most Halorubrum species. Based on the overall combination of physiological, phylogenetic, polar lipids and phylogenomic characteristics, strain 1-13-28T (= ATCC 700083T = CGMCC 1.62627T) represents a newly identified species within the genus Halorubrum for which the name Halorubrum hochsteinianum is proposed.

HACCP plan for microbiological hazards associated with fermented crab, Episesarma mederi H. Milne Edwards 1853.

AIMS: To develop a model HACCP plan related to the microbiological hazards for the traditional fermented crab. METHODS AND RESULTS: The microbiological and chemical characteristics of commercial products were surveyed. Microbiological hazard analysis was performed for raw materials and during processing. Critical control points (CCPs) were determined using a decision tree, with CCP1 as saturated salt preparation and CCP2 as fermentation. The critical limit (CL) of CCP1 was at 100°C for 20 min applied to brining and of CCP2 was at 25% NaCl for the brine applied to fermented crab. Isolated microbial hazards and type strains were used for the validation of the CLs. Monitoring and verification of the proposed HACCP plan were carried out, and an effective HACCP plan was established. CONCLUSIONS: The HACCP plan promoted the safe consumption of fermented crab with the provided CCPs at the saturated salt preparation and fermentation steps. The effective CLs to ensure microbiological hazards as safe at the CCPs provide the best support for an effective plan. The hazards were reduced significantly after the HACCP plan had been applied.

Paracoccus onchidii sp. nov., a moderately halophilic bacterium isolated from a marine invertebrate from the South China Sea.

A novel moderately halophilic bacterial strain, designated Z330T, was isolated from the egg of a marine invertebrate of the genus Onchidium collected in the South China Sea. The 16S rRNA gene sequence of strain Z330T exhibited the highest similarity value to that of the type strain Paracoccus fistulariae KCTC 22803T (97.6%), Paracoccus seriniphilus NBRC 100798T (97.6%) and Paracoccus aestuarii DSM 19484T (97.6%). Phylogenomic and 16S rRNA phylogenetic analysis showed that strain Z330T was most closely related to P. seriniphilus NBRC 100798T and P. fistulariae KCTC 22803T. Strain Z330T grew optimally at 28-30 °C, pH 7.0-8.0 with the presence of 5.0-7.0% (w/v) NaCl. In addition, growth of strain Z330T occurred at 0.5-16% NaCl, indicated strain Z330T was a moderately halophilic and halotolerant bacterium of genus Paracoccus. The predominant respiratory quinone in strain Z330T was identified as ubiquinone-10. The major polar lipids of strain Z330T were phosphatidylcholine, phosphatidylglycerol, diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylmonomethylethanolamine, glycolipid and six unidentified polar lipids. The major fatty acids of strain Z330T was summed feature 8 (C18:1 ω6c and/or C18:1 ω7c). The draft genome sequence of strain Z330T includes 4,084,570 bp in total (N50 = 174,985 bp) with a medium read coverage of 463.6 × and 83 scaffolds. The DNA G + C content of strain Z330T was 60.5%. In silico DNA-DNA hybridization with the four type strains showed 20.5, 22.3, 20.1 and 20.1% relatedness to Paracoccus fistulariae KCTC 22803T, Paracoccus seriniphilus NBRC 100798T, Paracoccus aestuarii DSM 19484T and Paracoccus denitrificans 1A10901T, respectively. And the average nucleotide identity (ANIb) values between strain Z330T and these four type strains were 76.2, 80.0, 75.8 and 73.8%, respectively, lower than the 95-96% threshold value for dividing prokaryotic species. On the basis of the phenotypic, phylogenetic, phylogenomic and chemotaxonomic properties, a novel species of the genus Paracoccus, Paracoccus onchidii sp. nov. is proposed with the type strain Z330T (= KCTC 92727T = MCCC 1K08325T).

Xinghamide A, a New Cyclic Nonapeptide Found in Streptomyces xinghaiensis.

Xinghamide A (1), a new nonapeptide, was discovered in Streptomyces xinghaiensis isolated from a halophyte, Suaeda maritima (L.) Dumort. Based on high-resolution mass and NMR spectroscopic data, the planar structure of 1 was established, and, in particular, the sequence of nine amino acids was determined with ROESY and HMBC NMR spectra. The absolute configurations of the α-carbon of each amino acid residue were determined with 1-fluoro-2,4-dinitrophenyl-l-and -d-leucine amide (Marfey's reagents) and 2,3,4,6-tetra-O-acetyl-ß-d-glucopyranosyl isothiocyanate, followed by LC-MS analysis. The anti-inflammatory activity of xinghamide A (1) was evaluated by inhibitory abilities against the nitric oxide (NO) secretion and cyclooxygenase-2 (COX-2) expression in lipopolysaccharide (LPS)-stimulated RAW264.7 cells.

Isolation and characterization of a main porin from the outer membrane of Salinibacter ruber.

Salinibacter ruber is an extremophilic bacterium able to grow in high-salts environments, such as saltern crystallizer ponds. This halophilic bacterium is red-pigmented due to the production of several carotenoids and their derivatives. Two of these pigment molecules, salinixanthin and retinal, are reported to be essential cofactors of the xanthorhodopsin, a light-driven proton pump unique to this bacterium. Here, we isolate and characterize an outer membrane porin-like protein that retains salinixanthin. The characterization by mass spectrometry identified an unknown protein whose structure, predicted by AlphaFold, consists of a 8 strands beta-barrel transmembrane organization typical of porins. The protein is found to be part of a functional network clearly involved in the outer membrane trafficking. Cryo-EM micrographs showed the shape and dimensions of a particle comparable with the ones of the predicted structure. Functional implications, with respect to the high representativity of this protein in the outer membrane fraction, are discussed considering its possible role in primary functions such as the nutrients uptake and the homeostatic balance. Finally, also a possible involvement in balancing the charge perturbation associated with the xanthorhodopsin and ATP synthase activities is considered.

Caldalkalibacillus salinus sp. nov., isolated from a salt lake in Xinjiang, northwest China.

A novel Gram-stain-negative, aerobic, motile and rod-shaped bacterium, designated as strain YIM B00319T, was isolated from a sediment sample obtained from Wuzunbulake salt Lake in Xinjiang Uygur Autonomous Region, northwest China. Phylogenetic analysis based on 16S rRNA gene sequences along with the whole genome showed that strain YIM B00319T belongs to the family Bacillaceae and was most closely related to Bacillus horti K13T and Caldalkalibacillus mannanilyticus JCM 10596T, with sequence similarities of 95.7% and 94.6%, respectively. The genome of strain YIM B00319T was 3.77 Mbp with a DNA G + C content of 43%. Strain YIM B00319T grew at 15-45 ℃, pH 7.0-9.5 and with 3-11% (w/v) NaCl. The major respiratory quinone of strain YIM B00319T was MK-7, and the major fatty acids (> 10%) were iso-C15:0, anteiso-C15:0, and summed feature 3 (C16:1 ω6c and/or C16:1 ω7c). The main polar lipids were phosphatidylethanolamine (PE), phosphatidylglycerol (PG), and diphosphatidylglycerol (DPG). The cell-wall peptidoglycan contained meso-diaminopimelic acid. On the basis of the phenotypic, chemotaxonomic, genomic, and phylogenetic information, strain YIM B00319T represents a novel species of the genus Caldalkalibacillus, for which the name Caldalkalibacillus salinus sp. nov. is proposed. The type strain is YIM B00319T (= CGMCC 1.18750T = NBRC 115338T).

Halomonas getboli sp. nov., a halotolerant bacteria isolated from a salt flat.

A novel Gram-stain-negative, rod-shaped, cream-coloured, motile, halotolerant bacterium, designated as YJPS3-2T, was isolated from saltern sediment of the Yellow sea in Yongyu-do, Republic of Korea. Strain YJPS3-2T grew at pH 5.0-10.0 (optimum, pH 7.0), 4-40 °C (optimum, 30 °C) and with 1-15% (w/v) NaCl (optimum 3 %). The 16S rRNA gene sequence analysis indicated that strain YJPS3-2T was closely related to those of Halomonas halophila F5-7T (98.75 %), Halomonas salina F8-11T (98.74 %), Halomonas smyrnensis AAD6T (98.66 %), Halomonas organivorans G-16.1T (98.34 %), Halomonas koreensis SS20T (97.98 %) and Halomonas beimenensis NTU-107T (96.93 %). The average nucleotide identity and digital DNA-DNA hybridization values between YJPS3-2T and related type strains were 86.9-91.6 % and 32.0-44.8 %. Strain YJPS3-2T was characterized as having Q-9 as the predominant respiratory quinone and the principal fatty acids (>10 %) were C16 : 0 (31.4 %), C19 : 0 ω8c cyclo (16.3 %), C17 : 0 cyclo (11.9 %) and C12 : 0 3-OH (10.4 %). The polar lipids consisted of phosphatidylcholine, diphosphatidylglycerol, phosphatidylethanolamine and phosphatidylglycerol. The DNA G+C content of strain YJPS3-2T is 68.1mol %. Based on the polyphasic taxonomic evidence presented in this study, YJPS3-2T should be classified as representing a novel species within the genus Halmonas, for which name Halomonas getboli is proposed, with the type strain YJPS3-2T (= KCTC 92124T=KACC 22561T=JCM 35085T).

Halomonas antri sp. nov., a carotenoid-producing bacterium isolated from surface seawater.

A Gram-negative, moderately halophilic bacterium, designated as strain Y3S6T, was isolated from a surface seawater sample collected from Dongangyoeng cave, Udo-myeon, Jeju-si, Jeju-do, Repulic of Korea. Cells of strain Y3S6T were aerobic, rod-shaped, non-sporulated, yellow, catalase- negative, oxidase-negative and motile with one polar flagellum. Growth of strain Y3S6T occurred at 15-40 °C (optimum: 25-30 °C), at pH 6.0-9.0 (optimum: pH 7.0) and in the presence of 0-13% NaCl (optimum: 1-6 %, w/v). The novel strain was able to produce carotenoids. Its chemotaxonomic and morphological characteristics were consistent with those of members of the genus Halomonas. Phylogenetic analysis of the 16S rRNA gene sequence revealed that strain Y3S6T formed a clade with Halomonas pellis L5T (98.97 %) and Halomonas saliphila LCB169T(98.90%). The average nucleotide identity and digital DNA-DNA hybridization values of strain Y3S6T with the most closely related strains for which whole genomes are publicly available were 82.3-85.2% and 62.8-66.1 %, respectively. The major fatty acids in strain Y3S6T were C16 : 0, C19 : 0 cyclo ω8c and summed feature 8 (composed of C18 : 1 ω7c and/or C18 : 1 ω6c), and the predominant quinone was Q-9. Its polar lipid profile consisted of diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine, two unidentified phosphoglycolipid, one unidentified phosphoaminoglycolipid and one unidentified phospholipid. The genomic DNA G+C content based on the draft genome sequence was 64.2 mol%. The results of physiological and biochemical tests and 16S rRNA sequence analysis clearly revealed that strain Y3S6T represents a novel species in the genus Halomonas, for which the name Halomonas antri sp. nov. has been proposed. The type strain is Y3S6T (=KACC 21536T=NBRC 114315=TBRC 15164T).

Sediminibacillus dalangtanensis sp. nov., a moderate halophile isolated from hypersaline sediments of the Qaidam Basin in Northwest China.

A Gram-stain-positive, moderately halophilic, aerobic, endospore-forming, rod-shaped bacterium, designated strain DP4-553-ST, was isolated from hypersaline sediment collected from the Dalangtan Playa in the Qaidam Basin, Northwest PR China. Growth occurred within 0-21.6% (w/v) NaCl (optimum 7.2%) at pH 5.5-9.0 (optimum pH 7.0) and at 4-45 °C (optimum 37 °C). Phylogeny based on 16S rRNA gene sequences indicated that strain DP4-553-ST belonged to the genus Sediminibacillus, with high 16S rRNA gene sequence similarity to Sediminibacillus halophilus EN8dT (99.5 %), Sediminibacillus terrae JSM 102062T (99.4 %), Virgibacillus senegalensis SK-1T (99.3 %) and Sediminibacillus albus NHBX5T (98.3 %). The G+C content of the chromosomal DNA was 43.6 mol %. The average amino acid identity, average nucleotide identity and digital DNA-DNA hybridization values between strain DP4-553-ST and the four close type strains were 71.2-93.3, 74.0-90.5 and 20.0-41.4 %, respectively. The whole genomic analysis showed that strain DP4-553-ST constituted a different taxon separated from the recognized Sediminibacillus species. The major cellular fatty acids were anteiso-C15 : 0, anteiso-C17 : 0, iso-C16 : 0, C16 : 0 and iso-C15 : 0. The type strain contained cell-wall peptidoglycan based on diaminopimelic acid and possessed menaquinone-7 as the major respiratory isoprenoid quinone. The polar lipid pattern consisted of diphosphatidylglycerol, phosphatidylglycerol, four unidentified glycolipids, phosphatidylcholine, aminophospholipid, aminolipid and seven unidentified phospholipids. The combined data from phenotypic and genotypic studies demonstrated that strain DP4-553-ST represents a novel species of the genus Sediminibacillus, for which the name Sediminibacillus dalangtanensis sp. nov. is proposed, the type strain is DP4-553-ST (=MCCC 1K03838T= KCTC 43250T).

Assessment of diversity of archaeal communities in Algerian chott.

Halophilic archaea are the dominant type of microorganisms in hypersaline environments. The diversity of halophilic archaea in Zehrez-Chergui (Saharian chott) was analyzed and compared by both analysis of a library of PCR amplified 16S rRNA genes and by cultivation approach. This work, represents the first of its type in Algeria. A total cell count was estimated at 3.8 × 103 CFU/g. The morphological, biochemical, and physiological characterizations of 45 distinct strains, suggests that all of them might be members of the class Halobacteria. Among stains, 23 were characterized phylogenetically and are related to 6 genera of halophilic archaea.The dominance of the genus Halopiger, has not been reported yet in other hypersaline environments. The 100 clones obtained by the molecular approach, were sequenced, and analyzed. The ribosomal library of 61 OTUs showed that the archaeal diversity included uncultured haloarcheon, Halomicrobium, Natronomonas, Halomicroarcula, Halapricum, Haloarcula, Halosimplex, Haloterrigena, Halolamina, Halorubellus, Halorussus and Halonotius. The results of rarefaction analysis indicated that the analysis of an increasing number of clones would have revealed additional diversity. Surprisingly, no halophilic archaea were not shared between the two approaches. Combining both types of methods was considered the best approach to acquire better information on the characteristics of soil halophilic archaea.

Study of osmoadaptation mechanisms of halophilic Halomonas alkaliphila XH26 under salt stress by transcriptome and ectoine analysis.

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.

Halomonas spp., as chassis for low-cost production of chemicals.

Halomonas spp. are the well-studied platform organisms or chassis for next-generation industrial biotechnology (NGIB) due to their contamination-resistant nature combined with their fast growth property. Several Halomonas spp. have been studied regarding their genomic information and molecular engineering approaches. Halomonas spp., especially Halomonas bluephagenesis, have been engineered to produce various biopolyesters such as polyhydroxyalkanoates (PHA), proteins including surfactants and enzymes, small molecular compounds including amino acids and derivates, as well as organic acids. This paper reviews all the progress reported in the last 10 years regarding this robust microbial cell factory. KEY POINTS: • Halomonas spp. are robust chassis for low-cost production of chemicals • Genomic information of some Halomonas spp. has been revealed • Molecular tools and approaches for Halomonas spp. have been developed • Halomonas spp. are becoming more and more important for biotechnology.

Effects of Salinity and Temperature on the Flexibility and Function of a Polyextremophilic Enzyme.

The polyextremophilic ß-galactosidase enzyme of the haloarchaeon Halorubrum lacusprofundi functions in extremely cold and hypersaline conditions. To better understand the basis of polyextremophilic activity, the enzyme was studied using steady-state kinetics and molecular dynamics at temperatures ranging from 10 °C to 50 °C and salt concentrations from 1 M to 4 M KCl. Kinetic analysis showed that while catalytic efficiency (kcat/Km) improves with increasing temperature and salinity, Km is reduced with decreasing temperatures and increasing salinity, consistent with improved substrate binding at low temperatures. In contrast, kcat was similar from 2-4 M KCl across the temperature range, with the calculated enthalpic and entropic components indicating a threshold of 2 M KCl to lower the activation barrier for catalysis. With molecular dynamics simulations, the increase in per-residue root-mean-square fluctuation (RMSF) was observed with higher temperature and salinity, with trends like those seen with the catalytic efficiency, consistent with the enzyme's function being related to its flexibility. Domain A had the smallest change in flexibility across the conditions tested, suggesting the adaptation to extreme conditions occurs via regions distant to the active site and surface accessible residues. Increased flexibility was most apparent in the distal active sites, indicating their importance in conferring salinity and temperature-dependent effects.

Isolation and Characterization of a Novel Lytic Halotolerant Phage from Yuncheng Saline Lake.

Halophilic phage are a type of virus that exist in salty environments within halophilic archaeal or bacterial hosts. However, relatively few reports on halophilic bacteriophages exist, and our overall understanding of halophilic bacteriophages is quite limited. We used SYBR Green I fluorescent staining to detect the abundance of viruses in Yuncheng Saline Lake, China. Using the double-layer plate method, a lytic phage that could infect halophilic bacterium Salinivibrio sp. YM-43 was isolated and named YXM43. We studied host range, optimal host, morphological characteristics, nucleic acid type, protein composition, and other biological characteristics of the virus. Results reveal a high abundance of this halophilic virus in Yuncheng Saline Lake. The newly isolated bacteriophage YXM43 has a narrow host range, with the most suitable host being Virgibacillus sp. SK39. After purification and enrichment, YXM43 is observed as a spherical particle with a diameter of approximately 30 nm, with no tail. No lipid envelope can be seen in YXM43. The capsid protein of the virus can be separated into seven proteins with molecular weights ranging from 62.0 to 13.0 kDa. YXM43 is a DNA virus with a genome approximately 23 kb. The virus is tolerant of low salinity, and its activity is highest at a temperature of 60 °C and a pH of 10. YXM43 is temperature and pH tolerant, and can adapt to environmental change, even withstanding chloroform treatment. The results indicate that bacteriophage YXM43 is a novel halophilic bacteriophage with broad tolerance to environmental change.