Halovenus rubra sp. nov., isolated from salted brown alga Laminaria

Biochemical characterization of a low salt-adapted extracellular protease from the extremely halophilic archaeon Halococcus salifodinae

Extracellular proteases from haloarchaea can expand the application fields of proteases. Exploring novel robust proteases is of great importance. An extracellular protease HlyA from Halococcus salifodinae was obtained by heterologous expression, affinity chromatography, in vitro refolding and gel filtration chromatography. Its activity was optimal at 45 °C, pH 9.0 and 1.5-2 M NaCl. Interestingly, although HlyA was from an extremely halophilic archaeon, it retained >75% of maximal activity in a broad NaCl concentration of 0.5-4 M. It displayed relatively stable activities over a wide range of temperature, pH and salinity. Thus, HlyA exhibited good temperature, pH and especially, salinity tolerance. Ca²⁺, Mg²⁺ and Sr²⁺ significantly enhanced the protease activity. HlyA activity was completely inhibited by phenylmethanesulfonyl fluoride (PMSF), suggesting it is a serine protease. HlyA showed good tolerance to some surfactants and organic solvents. The K_m and V_max values of HlyA for azocasein were calculated to be 0.72 mM and 21.98 U/μg, respectively. HlyA was able to effectively degrade several protein substrates, including bovine hemoglobin, casein and azocasein. Generally, HlyA from the extremely halophilic archaeon Hcc. salifodinae is an alkaliphilic and low salt-adapted halolysin with high activity, thus representing an attractive candidate for various industrial uses.

Salinibaculum litoreum gen. nov., sp. nov., isolated from salted brown alga Laminaria

A novel Gram-stain-negative, aerobic and rod-shaped halophilic archaeon, designated HD8-45T, was isolated from the red brine of salted brown alga Laminaria produced at Dalian, PR China. According to the results of 16S rRNA gene and rpoB' gene sequence comparisons, strain HD8-45T showed the highest sequence similarity to the corresponding genes of Salinirussus salinus YGH44T (95.1 and 85.2 % similarities, respectively), Halovenus aranensis EB27T (91.2 and 86.0 % similarities, respectively). The low sequence similarity and the phylogeny implied the novel generic status of strain HD8-45T. Genomic relatedness analyses showed that strain HD8-45T were clearly distinguished from other species in the order Halobacteriales, with average nucleotide identity, amino acid identity and in silico DNA-DNA hybridization values not more than 75.1, 65.6 and 21.5 %. The polar lipid pattern contained phosphatidylglycerol, phosphatidylglycerol phosphate methyl ester, two major glycolipids and two minor glycolipids. The two major glycolipids and a minor glycolipid were chromatographically identical to disulfated mannosyl glucosyl diether, sulfated mannosyl glucosyl diether and mannosyl glucosyl diether, respectively. The major respiratory quinones were menaquinone MK-8 and MK-8(H2). The DNA G+C content was 62.0 mol% (Tm) and 61.9 mol% (genome). All these results showed that strain HD8-45T represents a novel species of a new genus in the order Halobacteriales, for which the name Salinibaculum litoreum gen. nov., sp. nov. is proposed. The type strain of Salinibaculum litoreum is HD8-45T (=CGMCC 1.15328T=JCM 31107T).

Halostella pelagica sp. nov. and Halostella litorea sp. nov., isolated from salted brown alga Laminaria

Three rod-shaped halophilic archaeal strains, DL-M4T, LYG-109 and DLLS-108T, were isolated from the salted brown alga Laminaria produced in different marine areas of PR China. Cells of strains were motile, formed red-pigmented colonies on agar and lysed in distilled water. The three strains grew optimally with 2.6 M NaCl, with 0.05-0.3 M MgCl2, at 37 °C and at pH 7.0-7.5. The results of phylogenetic analyses based on the 16S rRNA and rpoB' genes differentiated these strains into two clusters belonging to the genus Halostella, which currently contains Halostella salina CBA1114T and Halostella limicola LT12T. Strains DL-M4T and LYG-109 formed a single cluster separate from the current two members of Halostella (94.4-95.7 and 90.0-90.9 % similarities, respectively) while strain DLLS-108T had Hsl. salina CBA1114T as its nearest neighbour (97.7-97.8 and 95.9 % similarities, respectively) and was separated from Hsl. limicola LT12T (94.4-95.8 and 93.4 % similarities, respectively). These clusters represented two distinct novel species as indicated by phenotypic characteristics, polar lipid compositions and whole-genome comparisons. Diverse phenotypic characteristics, morphology and growth characteristics, nutrition and miscellaneous biochemical tests differentiate strains DL-M4T, LYG-109, DLLS-108T from Hsl. limicola LT12T and Hsl. salina CBA1114T. Strains DL-M4T and LYG-109 contained phosphatidylglycerol, phosphatidylglycerol phosphate methyl ester and three unidentified glycolipids, while strain DLLS-108T contained these polar lipids and two unidentified phospholipids. The major respiratory quinones detected in the three isolates were menaquinone MK-8 and MK-8(H2). The average nucleotide identity (ANI) and in silico DNA-DNA hybridization (isDDH) values between the isolated strains and the current two members of Halostella were found to be 79.3-86.6 (ANI) and 22.9-49.8 % (isDDH). All these results showed that the three isolates represent two novel species of the genus Halostella for which the names Halostella pelagica sp. nov. [type strain dl-M4T (=CGMCC 1.13603T=JCM 32954T)] and Halostella litorea sp. nov. [type strain DLLS-108T(=CGMCC 1.13610T=JCM 32955T)] are proposed.

Development of microbial community within the cathodic biofilm of single-chamber air-cathode microbial fuel cell

The aim of this study was to investigate the development of microbial community within the cathodic biofilm of single-chamber air-cathode microbial fuel cell (MFC). To analyze microbial community structures within cathodic biofilm, cathodic biofilm samples were stratified into three layers, i.e., the cathode-side layer (0-40 μm), the middle layer (40-80 μm), and the anolyte-side layer (80-120 μm). After four starting cycles (0-188 h), the maximum power densities of the MFC fed with 1 g/L acetate decreased from 1056 ± 110 to 410 ± 50 mW/m² within 15 cycles (~30 d) of operation. The relative abundance of Pseudomonas gradually increased from 18.9% in the 1st cycle to 50.2% in the 4th cycle. After 15 cycles, the relative abundance of Pseudomonas became 53.8%, 16.4%, and 8.90% in the middle, anolyte-side, and cathode-side layers, respectively. The aerobic bacteria within the cathodic biofilm increased from 24% in the anodyte-side layer to 43% in the cathode-side layer. The relative abundance of Methanobrevibacter was 42.1% and 37.2% after 3 and 15 cycles, respectively. The bacterial community structures were similar among cycles 2, 3, and 4, but significantly different in the 15th cycle. The results from this study should be useful to understand the mechanism of the cathodic biofilm formation and to develop strategies to enhance performance of the MFC.

Halorussus litoreus sp. nov., isolated from the salted brown alga Laminaria

A halophilic archaeal strain, designated HD8-51T, was isolated from the salted brown alga Laminaria. Cells of strain HD8-51T were motile, pleomorphic coccoid or ovoid, and formed red-pigmented colonies on agar plates. Strain HD8-51T grew optimally at 3.1 M NaCl, 0.03 M MgCl2, 30 °C and pH 7.0. Cells lysed in distilled water and the minimal NaCl concentration to prevent cell lysis was 0.85 M. Based on phylogenetic analyses of the 16S rRNA and rpoB' genes, strain HD8-51T was most closely related to members of the genus Halorussus (92.3-95.6 % and 89.2-91.7% similarities, respectively). The average nucleotide identity values and in silico DNA-DNA hybridization values between strain HD8-51T and Halorussus rarus TBN4T were 81.69 and 24.5 %, respectively. The major polar lipids of strain HD8-51T were phosphatidic acid (PA), phosphatidylglycerol (PG), phosphatidylglycerol phosphate methyl ester (PGP-Me), phosphatidylglycerol sulfate (PGS) and five glycolipids, sulfated galactosyl mannosyl glucosyl diether (S-TGD-1), galactosyl mannosyl glucosyl diether (TGD-1), sulfated mannosyl glucosyl diether (S-DGD-1), mannosyl glucosyl diether (DGD-1) and diglycosyl diether (DGD-2). The DNA G+C content was 65.9 mol%. Based on phenotypic, chemotaxonomic and phylogenetic properties, strain HD8-51T represents a novel species of the genus Halorussus, for which the name Halorussus litoreus sp. nov. is proposed. The type strain is HD8-51T (=CGMCC 1.15333T=JCM 31109T).

Systematics of haloarchaea and biotechnological potential of their hydrolytic enzymes

Halophilic archaea, also referred to as haloarchaea, dominate hypersaline environments. To survive under such extreme conditions, haloarchaea and their enzymes have evolved to function optimally in environments with high salt concentrations and, sometimes, with extreme pH and temperatures. These features make haloarchaea attractive sources of a wide variety of biotechnological products, such as hydrolytic enzymes, with numerous potential applications in biotechnology. The unique trait of haloarchaeal enzymes, haloenzymes, to sustain activity under hypersaline conditions has extended the range of already-available biocatalysts and industrial processes in which high salt concentrations inhibit the activity of regular enzymes. In addition to their halostable properties, haloenzymes can also withstand other conditions such as extreme pH and temperature. In spite of these benefits, the industrial potential of these natural catalysts remains largely unexplored, with only a few characterized extracellular hydrolases. Because of the applied impact of haloarchaea and their specific ability to live in the presence of high salt concentrations, studies on their systematics have intensified in recent years, identifying many new genera and species. This review summarizes the current status of the haloarchaeal genera and species, and discusses the properties of haloenzymes and their potential industrial applications.

List of new names and new combinations previously effectively, but not validly, published

The purpose of this announcement is to effect the valid publication of the following effectively published new names and new combinations under the procedure described in the Bacteriological Code (1990 Revision). Authors and other individuals wishing to have new names and/or combinations included in future lists should send three copies of the pertinent reprint or photocopies thereof, or an electronic copy of the published paper to the IJSEM Editorial Office for confirmation that all of the other requirements for valid publication have been met. It is also a requirement of IJSEM and the ICSP that authors of new species, new subspecies and new combinations provide evidence that types are deposited in two recognized culture collections in two different countries. It should be noted that the date of valid publication of these new names and combinations is the date of publication of this list, not the date of the original publication of the names and combinations. The authors of the new names and combinations are as given below. Inclusion of a name on these lists validates the publication of the name and thereby makes it available in the nomenclature of prokaryotes. The inclusion of a name on this list is not to be construed as taxonomic acceptance of the taxon to which the name is applied. Indeed, some of these names may, in time, be shown to be synonyms, or the organisms may be transferred to another genus, thus necessitating the creation of a new combination.