Prokaryotic Communities in the Thalassohaline Tuz Lake, Deep Zone, and Kayacik, Kaldirim and Yavsan Salterns (Turkey) Assessed by 16S rRNA Amplicon Sequencing.

Prokaryotic communities and physico-chemical characteristics of 30 brine samples from the thalassohaline Tuz Lake (Salt Lake), Deep Zone, Kayacik, Kaldirim, and Yavsan salterns (Turkey) were analyzed using 16S rRNA amplicon sequencing and standard methods, respectively. Archaea (98.41% of reads) was found to dominate in these habitats in contrast to the domain Bacteria (1.38% of reads). Representatives of the phylum Euryarchaeota were detected as the most predominant, while 59.48% and 1.32% of reads, respectively, were assigned to 18 archaeal genera, 19 bacterial genera, 10 archaeal genera, and one bacterial genus that were determined to be present, with more than 1% sequences in the samples. They were the archaeal genera Haloquadratum, Haloarcula, Halorhabdus, Natronomonas, Halosimplex, Halomicrobium, Halorubrum, Halonotius, Halolamina, Halobacterium, and Salinibacter within the domain Bacteria. The genera Haloquadratum and Halorhabdus were found in all sampling sites. While Haloquadratum, Haloarcula, and Halorhabdus were the most abundant genera, two uncultured Tuz Lake Halobacteria (TLHs) 1 and 2 were detected in high abundance, and an additional uncultured haloarchaeal TLH-3 was found as a minor abundant uncultured taxon. Their future isolation in pure culture would permit us to expand our knowledge on hypersaline thalassohaline habitats, as well as their ecological role and biomedical and biotechnological potential applications.

Preparation, characterization, and in vitro evaluation of isoniazid and rifampicin-loaded archaeosomes.

The ability of Archaea to adapt their membrane lipid compositions to extreme environments has brought in archaeosomes into consideration for the development of drug delivery systems overcoming the physical, biological blockades that the body exhibits against drug therapies. In this study, we prepared unilamellar archaeosomes, from the polar lipid fraction extracted from Haloarcula 2TK2 strain, and explored its potential as a drug delivery vehicle. Rifampicin and isoniazid which are conventional drugs in tuberculosis medication were loaded separately and together in the same archaeosome formulation for the benefits of the combined therapy. Particle size and zeta potential of archaeosomes were measured by photon correlation spectroscopy, and the morphology was assessed by with an atomic force microscope. Encapsulation efficiency and loading capacities of the drugs were determined, and in vitro drug releases were monitored spectrophotometrically. Our study demonstrates that rifampicin and isoniazid could be successfully loaded separately and together in archaeosomes with reasonable drug-loading and desired vesicle-specific characters. Both of the drugs had greater affinity for archaeosomes than a conventional liposome formulation. The results imply that archaeosomes prepared from extremely halophilic archaeon were compatible with the liposomes for the development of stable and sustained release of antituberculosis drugs.

Preparation of poly(3-hydroxybutyrate-co-hydroxyvalerate) films from halophilic archaea and their potential use in drug delivery.

Halophilic archaea offer a potential source for production of polyhydroxyalkanoates (PHAs). Hence, the experiments were carried out with five extremely halophilic archaeal isolates to determine the highest PHA-producing strain. PHA production of each isolates was separately examined in cheap carbon sources such as corn starch, sucrose, whey, apple, melon and tomato wastes. Corn starch was found to be a fairly effective substrate for PHA production. Among the strains studied here, the strain with the highest capability for PHA biosynthesis was found to be 1KYS1. Phylogenetic analysis based on 16S rRNA gene sequence comparison showed that 1KYS1 closely related to species of the genus Natrinema. The closest phylogenetic similarity was with the strain of Natrinema pallidum JCM 8980 (99 %). PHA content of 1KYS1 was about 53.14 % of the cell dry weight when starch was used as a carbon source. The formation of large and uniform PHA granules was confirmed by transmission electron microscopy and the biopolymer was identified as poly(3-hydroxybutyrate-co-hydroxyvalerate) (PHBV). PHBV produced by 1KYS1 was blended with low molar mass polyethylene glycol (PEG 300) to prepare biocompatible films for drug delivery. Rifampicin was used as a model drug and its release from PHBV films was investigated at pH 7.4, 37 °C. It was found that PHBV films obtained from 1KYS1 were very effective for drug delivery. In conclusion, PHBV of 1KYS1 may have a potential usage in drug delivery applications.

Salimicrobium salexigens sp. nov., a moderately halophilic bacterium from salted hides.

Two Gram-positive, moderately halophilic bacteria, designated strains 29CMI(T) and 53CMI, were isolated from salted hides. Both strains were non-motile, strictly aerobic cocci, growing in the presence of 3-25% (w/v) NaCl (optimal growth at 7.5-12.5% [w/v] NaCl), between pH 5.0 and 10.0 (optimal growth at pH 7.5) and at temperatures between 15 and 40°C (optimal growth at 37°C). Phylogenetic analysis based on 16S rRNA gene sequence comparison showed that both strains showed a similarity of 98.7% and were closely related to species of the genus Salimicrobium, within the phylum Firmicutes. Strains 29CMI(T) and 53CMI exhibited 16S rRNA gene sequence similarity values of 97.9-97.6% with Salimicrobium album DSM 20748(T), Salimicrobium halophilum DSM 4771(T), Salimicrobium flavidum ISL-25(T) and Salimicrobium luteum BY-5(T). The DNA G+C content was 50.7mol% and 51.5mol% for strains 29CMI(T) and 53CMI, respectively. The DNA-DNA hybridization between both strains was 98%, whereas the values between strain 29CMI(T) and the species S. album CCM 3517(T), S. luteum BY-5(T), S. flavidum ISL-25(T) and S. halophilum CCM 4074(T) were 45%, 28%, 15% and 10%, respectively, showing unequivocally that strains 29CMI(T) and 53CMI constitute a new genospecies. The major cellular fatty acids were anteiso-C(15:0), anteiso-C(17:0), iso-C(15:0) and iso-C(14:0). The main respiratory isoprenoid quinone was MK-7, although small amounts of MK-6 were also found. The polar lipids of the type strain consist of diphosphatidylglycerol, phosphatidylglycerol, one unidentified phospholipid and one glycolipid. The peptidoglycan type is A1γ, with meso-diaminopimelic acid as the diagnostic diamino acid. On the basis of the phylogenetic analysis, and phenotypic, genotypic and chemotaxonomic characteristics, we propose strains 29CMI(T) and 53CMI as a novel species of the genus Salimicrobium, with the name Salimicrobium salexigens sp. nov. The type strain is 29CMI(T) (=CECT 7568(T)=JCM 16414(T)=LMG 25386(T)).

Thalassobacillus pellis sp. nov., a moderately halophilic, Gram-positive bacterium isolated from salted hides.

A Gram-positive, moderately halophilic and endospore-forming bacterium, designated strain 18OM(T), was isolated from salted animal hides. The cells were rods and produced ellipsoidal endospores at a terminal position. Strain 18OM(T) was motile, strictly aerobic and grew at 0.5-25 % (w/v) NaCl [optimal growth at 10 % (w/v) NaCl], at between pH 5.0 and 9.0 (optimal growth at pH 7.5) and at temperatures between 15 and 45 °C (optimal growth at 37 °C). Phylogenetic analysis based on 16S rRNA gene sequence comparisons showed that strain 18OM(T) was closely related to species of the genus Thalassobacillus within the phylum Firmicutes. The closest phylogenetic similarity was with Thalassobacillus devorans G-19.1(T) (98.4 %), Thalassobacillus cyri HS286(T) (97.9 %) and Thalassobacillus hwangdonensis AD-1(T) (97.4 %). The major cellular fatty acids were anteiso-C(15 : 0) (57.9 %), anteiso-C(17 : 0) (14.0 %), iso-C(15 : 0) (10.8 %) and iso-C(16 : 0) (8.1 %). The respiratory isoprenoid quinones were MK-7 (98.5 %) and MK-6 (1.5 %). The DNA G+C content was 42.9 mol%. These features confirmed the placement of strain 18OM(T) within the genus Thalassobacillus. The DNA-DNA hybridization values between strain 18OM(T) and T. devorans G-19.1(T), T. cyri HS286(T) and T. hwangdonensis AD-1(T) were 49 %, 9 % and 15 %, respectively, showing unequivocally that strain 18OM(T) constituted a novel genospecies. On the basis of phylogenetic analysis and phenotypic, genotypic and chemotaxonomic characteristics, strain 18OM(T) is considered to represent a novel species of the genus Thalassobacillus, for which the name Thalassobacillus pellis sp. nov. is proposed. The type strain is 18OM(T) ( = CECT 7566(T) = DSM 22784(T) = JCM 16412(T)).