Aquibaculum sediminis sp. nov., a halotolerant bacteria isolated from salt lake sediment.

An aerobic, Gram-stain negative bacterium was isolated from sediment samples of Barkol salt lake in Hami City, Xinjiang Uygur Autonomous Region, China, with the number EGI_FJ10229T. The strain is ellipse-shaped, oxidase-negative, catalase-positive, and has white, round, smooth, opaque colonies on marine 2216 E agar plate. Growth occurs at 4.0-37.0 â„ƒ (optimal:30.0 â„ƒ), pH 7.0-9.0 (optimal: pH 8.0) and NaCl concentration of 0-8.0% (optimal: 3.0%). Phylogenetic analysis based on 16S rRNA gene and genome sequences indicated that the isolated strain should be assigned to the genus Aquibaculum and was most closely related to Aquibaculum arenosum CAU 1616 T. Average nucleotide identity (ANI) and Average amino-acid identity (AAI) values between the type species of the genus Aquibaculum and other related type species were lower than the threshold values recommended for bacterial species. The genomic DNA G + C content of EGI_FJ10229T was 65.41%. The major polar lipids were diphosphatidylglycerol, phosphatidylmethylethanolamine, phosphatidylcholine, phosphatidylethanolamine and unidentified phospholipid. The major fatty acids (> 5%) were C19:0 cyclo ω8c (42.0%) and C18:1 ω7c (33.78%). The respiratory quinone identified was Q-10. Differential phenotypic and genotypic characteristics of this strain and species of genus Aquibaculum showed that the strain should be classified as representing a new species belonging to this genus, for which the name Aquibaculum sediminis sp. nov. is proposed. The type strain of the proposed novel species is EGI_FJ10229T (= KCTC 8570 T = GDMCC 1.4598 T).

Unveiling the impacts of salts on halotolerant bacteria during filtration: A new perspective on membrane biofouling formation in MBR treating high-saline organic wastewater.

In recent decades, membrane bioreactor (MBR) has been prevalently employed to treat high-saline organic wastewater, where the halotolerant microorganisms should be intensively utilized. However, limited works were devoted to investigating the biofouling characteristics from the perspective of the relationship between halotolerant bacteria and salts. This work filled the knowledge gap by exploring the biofouling formation mechanisms affected by high salinity. The results showed that the amount of negative charge on halotolerant bacteria surface was significantly reduced by high content of NaCl, probably leading to the obvious cell agglomeration. Despite the normal proliferation, the halotolerant bacteria still produced substantial EPS triggered by high salinity. Compared with the case of control without salt addition, the enhanced biofouling development was observed under high-saline conditions, with the fouling mechanism dramatically transformed from cake filtration to intermediate blocking. It was inferred that the halotolerant bacteria initially adhered on membrane created an extra filter layer, which contributed to the subsequent NaCl retention, resulting in the simultaneous occurrences of pore blockage and cake layer formation because of NaCl deposition both on membrane pores as well as on biofilm layer. Under high-saline environment, remarkable salt crystallization occurred on the biofilm layer, with more protein secreted by the attached halotolerant bacteria. Consequently, the potential mechanisms for the enhanced biofouling formation influenced by high salinity were proposed, which should provide new insights and enlightenments on fouling control strategies for MBR operation when treating high-saline organic wastewater.

Diversity and Biotechnological Potential of Cultivable Halophilic and Halotolerant Bacteria from the "Los Negritos" Geothermal Area.

Soil salinization is negatively affecting soils globally, and the spread of this problem is of great concern due to the loss of functions and benefits offered by the soil resource. In the present study, we explored the diversity of halophilic and halotolerant microorganisms in the arable fraction of a sodic-saline soil without agricultural practices and two soils with agricultural practices (one sodic and one saline) near the geothermal area "Los Negritos" in Villamar, Michoacán state. This was achieved through their isolation and molecular identification, as well as the characterization of their potential for the production of metabolites and enzymes of biotechnological interest under saline conditions. Using culture-dependent techniques, 62 halotolerant and moderately halophilic strains belonging to the genera Bacillus, Brachybacterium, Gracilibacillus, Halobacillus, Halomonas, Kocuria, Marinococcus, Nesterenkonia, Oceanobacillus, Planococcus, Priestia, Salibactetium, Salimicrobium, Salinicoccus, Staphylococcus, Terribacillus, and Virgibacillus were isolated. The different strains synthesized hydrolytic enzymes under 15% (w/v) of salts, as well as metabolites with plant-growth-promoting (PGP) characteristics, such as indole acetic acid (IAA), under saline conditions. Furthermore, the production of biopolymers was detected among the strains; members of Bacillus, Halomonas, Staphylococcus, and Salinicoccus showed extracellular polymeric substance (EPS) production, and the strain Halomonas sp. LNSP3E3-1.2 produced polyhydroxybutyrate (PHB) under 10% (w/v) of total salts.

Competitive mechanism of salt-tolerance/degradation-performance of organic pollutant in bacteria: Na+/H+ antiporters contribute to salt-stress resistance but impact phenol degradation.

Phenolic-laden wastewater is typically characterized by its high toxicity and high salinity, imposing serious limits on the application of bioremediation. Although a few halotolerant microorganisms have been reported to degrade phenol, their removal efficiency on high concentrations of phenol remains unsatisfactory. What's more, the deep interaction molecular mechanism of salt-tolerance/phenol-degradation performance has not been clearly revealed. Here, a halotolerant strain Aeribacillus pallidus W-12 employed a meta-pathway to efficiently degrade high concentration of phenol even under high salinity conditions. Investigation of salt-tolerance strategy indicated that four Na+/H+ antiporters, which are widely distributed in bacteria, synergistically endowed the strain with excellent salt adaptability. All these antiporters differentially but positively responded to salinity changes and induction of phenol, forming a synergistic transport effect on salt ions and phenol. In-depth analysis revealed a competitive relationship between salt tolerance and degradation performance, which significantly impaired the degradation efficiency at relatively high salinity. The efficient degradation performance of W-12 under different phenol concentrations and salinity conditions indicated its bioremediation potential for multiple types of phenolic wastewater. Collectively, the competitive mechanism of salt tolerance and degradation performance enlightens a new strategy of introducing or re-constructing Na+/H+ antiporters to further improve bioremediation efficiency of hypersaline organic wastewater.

The Halotolerant Probiotic Bacterium Enterococcus lactis ASF-2 from Al-Asfar Lake, Saudi Arabia, Reduces Inflammation in Carrageenan-Induced Paw Edema.

Inflammation-related diseases are major causes of mortality and disability worldwide. This study aimed to identify and investigate probiotic bacteria that could be present in Al-Asfar Lake in Al-Ahsa City, Saudi Arabia to prevent the inflammatory responses of carrageenan-induced paw edema. In total, seven active strains were isolated, and three isolates (ASF-1, ASF-2, and ASF-3) exhibited a positive Gram stain and viable growth at 20% NaCl salinity; they also lacked catalase and hemolytic activities and had high levels of cell surface hydrophobicity (CSH). They also demonstrated potent antibacterial activity against Salmonella typhi and Staphylococcus aureus. These results revealed that ASF-2 had probiotic qualities, and it was selected for further research. ASF-2 demonstrated significant anti-inflammatory effects in an experimental model of carrageenan-induced paw edema; the experimental model showed decreased levels of pro-inflammatory markers, such as interleukin 6 (IL-6), interleukin 17 (IL-17), and transforming growth factor-ß (TGF-ß), and an increased level of an anti-inflammatory marker (interferon gamma (IFN-γ)). Animals in the control group saw a 45% decrease in edema when compared to mice in the carrageenan group. When comparing tissue damage and infiltration in the ASF-2-treated and non-treated mice, the histological examination of the sub-planar tissues of the hind leg revealed that the inflamed tissues had healed. The 16S rRNA sequencing method was utilized to establish that ASF-2 is, in fact, Enterococcus lactis with a 99.2% sequence similarity. These findings shed further light on ASF-2's potential as a biocompatible anti-inflammatory medication.

The halophilic bacteria Gracilibacillus dipsosauri GDHT17 alleviates salt stress on perennial ryegrass seedlings.

Introduction: Adverse abiotic environmental conditions including excess salt in the soil, constantly challenge plants and disrupt the function of plants, even inflict damage on plants. Salt stress is one of the major limiting factors for agricultural productivity and severe restrictions on plant growth. One of the critical ways to improve plant salt tolerance is halotolerant bacteria application. However, few such halotolerant bacteria were known and should be explored furtherly. Methods: Halophilic bacterium strain was isolated from saline soil with serial dilution and identified with classical bacteriological tests and 16S rRNA analysis. Perennial ryegrass (Lolium perenne L) was used in this study to evaluate the potential effect of the bacteria. Results and discussion: A halophilic bacterium strain GDHT17, was isolated from saline soil, which grows in the salinities media with 1.0%, 5.0%, and 10.0% (w/v) NaCl, and identified as Gracilibacillus dipsosauri. Inoculating GDHT17 can significantly promote ryegrass's seedling height and stem diameter and increase the root length, diameter, and surface area at different salt concentrations, indicating the significant salt stress alleviating effect of GDHT17 on the growth of ryegrass. The alleviating effect on roots growth showed more effective, especially on the root length, which increased significantly by 26.39%, 42.59%, and 98.73% at salt stress of 100 mM, 200 mM, and 300 mM NaCl when the seedlings were inoculated with GDHT17. Inoculating GDHT17 also increases perennial ryegrass biomass, water content, chlorophyll and carotenoid content under salt stress. The contents of proline and malonaldehyde in the seedlings inoculated with GDHT17 increased by 83.50% and 6.87%, when treated with 300 mM NaCl; however, the contents of MDA and Pro did not show an apparent effect under salt stress of 100 mM or 200 mM NaCl. GDHT17-inoculating maintained the Na+/K+ ratio in the salt-stressed ryegrass. The Na+/K+ ratio decreased by 26.52%, 6.89%, and 29.92% in the GDHT17-inoculated seedling roots treated with 100 mM, 200 mM, and 300 mM NaCl, respectively. The GDHT17-inoculating increased the POD and SOD activity of ryegrass seedlings by 25.83% and 250.79%, respectively, at a salt stress of 300 mM NaCl, indicating the properties of GDHT17, improving the activity of antioxidant enzymes of ryegrass at the salt-stress condition. Our results suggest that G. dipsosauri GDHT17 may alleviate salt stress on ryegrass in multiple ways; hence it can be processed into microbial inoculants to increase salt tolerance of ryegrass, as well as other plants in saline soil.

Improving Grapevine Heat Stress Resilience with Marine Plant Growth-Promoting Rhizobacteria Consortia.

Amid climate change, heatwave events are expected to increase in frequency and severity. As a result, yield losses in viticulture due to heatwave stress have increased over the years. As one of the most important crops in the world, an eco-friendly stress mitigation strategy is greatly needed. The present work aims to evaluate the physiological fitness improvement by two marine plant growth-promoting rhizobacteria consortia in Vitis vinifera cv. Antão Vaz under heatwave conditions. To assess the potential biophysical and biochemical thermal stress feedback amelioration, photochemical traits, pigment and fatty acid profiles, and osmotic and oxidative stress biomarkers were analysed. Bioaugmented grapevines exposed to heatwave stress presented a significantly enhanced photoprotection capability and higher thermo-stability, exhibiting a significantly lower dissipation energy flux than the non-inoculated plants. Additionally, one of the rhizobacterial consortia tested improved light-harvesting capabilities by increasing reaction centre availability and preserving photosynthetic efficiency. Rhizobacteria inoculation expressed an osmoprotectant promotion, revealed by the lower osmolyte concentration while maintaining leaf turgidity. Improved antioxidant mechanisms and membrane stability resulted in lowered lipid peroxidation product formation when compared to non-inoculated plants. Although the consortia were found to differ significantly in their effectiveness, these findings demonstrate that bioaugmentation induced significant heatwave stress tolerance and mitigation. This study revealed the promising usage of marine PGPR consortia to promote plant fitness and minimize heatwave impacts in grapevines.

Coping with salt stress-interaction of halotolerant bacteria in crop plants: A mini review.

Salinity is one of the major environmental abiotic stress factors that limit the growth and yield of crop plants worldwide. It is crucial to understand the importance of several adaptive mechanisms in plants toward salt stress so as to increase agricultural productivity. Plant resilience toward salinity stress is improved by cohabiting with diverse microorganisms, especially bacteria. In the last few decades, increasing attention of researchers has focused on bacterial communities for promoting plant growth and fitness. The biotechnological applications of salt-tolerant plant growth-promoting rhizobacteria (PGPR) gained widespread interest for their numerous metabolites. This review provides novel insights into the importance of halotolerant (HT) bacteria associated with crop plants in enhancing plant tolerance toward salinity stress. Furthermore, the present review highlights several challenges of using HT-PGPR in the agricultural field and possible solutions to overcome those challenges for sustainable agriculture development in the future.

Enzymatic biodegradation, kinetic study, and detoxification of Reactive Red-195 by Halomonas meridiana isolated from Marine Sediments of Andaman Sea, India.

Azo dyes are a significant class of hazardous chemicals that are extensively utilised in diverse industries. Industries that manufacture and consume reactive azo dyes generate hyper-saline wastewater. The ability of halotolerant bacteria to thrive under extreme environmental conditions thus makes them a potential candidate for reactive azo dye degradation. An efficient halotolerant bacterium (isolate SAIBP-6) with the capability to degrade 87.15% of azo dye Reactive Red 195 (RR-195) was isolated from sea sediment and identified as Halomonas meridiana SAIBP-6. Strain SAIBP-6 maintained potential decolourisation under a wide range of environmental conditions viz. 35-45°C temperature, 50-450 mg/L RR-195, pH 7-9, and 50-150 g/L NaCl. However, maximum decolourisation occurred at 40°C, 200 mg/L RR-195 dye, pH 9, and 50 g/L NaCl, under static conditions. Tyrosinase and azoreductase were responsible for dye degradation. The reaction catalysed by these enzymes followed zero-order kinetics. The maximum velocity (Vmax) of the enzymatic reaction was 4.221 mg/(L.h) and the Michaelis constant (Km) was 517.982 mg/L. Strain SAIBP-6 also efficiently decolourised Reactive Black-5 and Reactive Yellow-160 dye. The biodegradation process was further studied with the help of UV-Vis spectral scan, ultra-high performance liquid chromatography (UPLC), fourier-transform infra-red spectroscopy (FT-IR), and proton nuclear magnetic resonance (1H NMR) analysis. Finally, cytogenotoxicity assay conducted with the meristematic root tip cells of Allium cepa and phytotoxicity assay conducted with the seeds of Vigna mungo led to the inference that strain SAIBP-6 significantly reduced the toxicity of RR-195 after biodegradation.

Efficient biodegradation of acetoacetanilide in hypersaline wastewater with a synthetic halotolerant bacterial consortium.

The high concentrations of salt and refractory toxic organics in industrial wastewater seriously restrict biological treatment efficiency and functional stability. However, how to construct a salt-tolerant biocatalytic community and realize the decarbonization coupled with detoxification toward green bio-enhanced treatment, has yet to be well elucidated. Here, acetoacetanilide (AAA), an important intermediate for many dyes and medicine synthesis, was used as the model amide pollutant to elucidate the directional enrichment of halotolerant degradative communities and the corresponding bacterial interaction mechanism. Combining microbial community composition and molecular ecological network analyses as well as the biodegradation efficiencies of AAA and its hydrolysis product aniline (AN) of pure strains, the core degradative bacteria were identified during the hypersaline AAA degradation process. A synthetic bacterial consortium composed of Paenarthrobacter, Rhizobium, Rhodococcus, Delftia and Nitratireductor was constructed based on the top-down strategy to treat AAA wastewater with different water quality characteristics. The synthetic halotolerant consortium showed promising treatment ability toward the simulated AAA wastewater (AAA 100-500 mg/L, 1-5% salinity) and actual AAA mother liquor. Additionally, the comprehensive toxicity of AAA mother liquor significantly reduced after biological treatment. This study provides a green biological approach for the treatment of hypersaline and high concentration of organics wastewater.

Characterization, Anti-proliferative Activity, and Bench-Scale Production of Novel pH-Stable and Thermotolerant L-Asparaginase from Bacillus licheniformis PPD37.

Bacterial L-asparaginase (LA) is a chemotherapeutic drug that has remained mainstay of cancer treatment for several decades. LA has been extensively used worldwide for the treatment of acute lymphoblastic leukemia (ALL). A halotolerant bacterial strain Bacillus licheniformis sp. isolated from marine environment was used for LA production. The enzyme produced was subjected to purification and physico-chemical characterisation. Purified LA was thermotolerant and demonstrated more than 90% enzyme activity after 1 h of incubation at 80 °C. LA has also proved to be resistant against pH gradient and retained activity at pH ranging from 3.0 to 10. The enzyme also had high salinity tolerance with 90% LA activity at 10% NaCl concentration. Detergents like Triton X-100 and Tween-80 were observed to inhibit LA activity while more than 70% catalytic activity was maintained in the presence of metals. Electrophoretic analysis revealed that LA is a heterodimer (~ 63 and ~ 65 kDa) and has molecular mass of around 130 kDa in native form. The kinetic parameters of LA were tested with LA having low Km value of 1.518 µM and Vmax value of 6.94 µM/min/mL. Purified LA has also exhibited noteworthy antiproliferative activity against cancer cell lines-HeLa, SiHa, A549, and SH-SY-5Y. In addition, bench-scale LA production was conducted in a 5-L bioreactor using moringa leaves as cost-effective substrate.

Co-Culture of Halotolerant Bacteria to Produce Poly(3-hydroxybutyrate-co-3-hydroxyvalerate) Using Sewage Wastewater Substrate.

The focus of the current study was the use of sewage wastewater to obtain PHA from a co-culture to produce a sustainable polymer. Two halotolerant bacteria, Bacillus halotolerans 14SM (MZ801771) and Bacillus aryabhattai WK31 (MT453992), were grown in a consortium to produce PHA. Sewage wastewater (SWW) was used to produce PHA, and glucose was used as a reference substrate to compare the growth and PHA production parameters. Both bacterial strains produced PHA in monoculture, but a copolymer was obtained when the co-cultures were used. The co-culture accumulated a maximum of 54% after 24 h of incubation in 10% SWW. The intracellular granules indicated the presence of nucleation sites for granule initiation. The average granule size was recorded to be 231 nm; micrographs also indicated the presence of extracellular polymers and granule-associated proteins. Fourier transform infrared spectroscopy (FTIR) analysis of the polymer produced by the consortium showed a significant peak at 1731 cm-1, representing the C=O group. FTIR also presented peaks in the region of 2800 cm-1 to 2900 cm-1, indicating C-C stretching. Proton nuclear magnetic resonance (1HNMR) of the pure polymer indicated chemical shifts resulting from the proton of hydroxy valerate and hydroxybutyrate, confirming the production of poly(3-hydroxybutyrate-co-3-hydroxy valerate) (P3HBV). A 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) assay showed that the copolymer was biocompatible, even at a high concentration of 5000 µg mL-1. The results of this study show that bacterial strains WK31 and 14SM can be used to synthesize a copolymer of butyrate and valerate using the volatile fatty acids present in the SWW, such as propionic acid or pentanoic acid. P3HBV can also be used to provide an extracellular matrix for cell-line growth without causing any cytotoxic effects.

Inoculating indoleacetic acid bacteria promotes the enrichment of halotolerant bacteria during secondary fermentation of composting.

The secondary fermentation stage is critical for stabilizing composting products and producing various secondary metabolites. However, the low metabolic rate of mesophilic bacteria is regarded as the rate-limiting stage in composting process. In present study, two indoleacetic acid (IAA)-producing bacteria (Bacillus safensis 33C and Corynebacterium stationis subsp. safensis 29B) were inoculated to strengthen the secondary fermentation stage to improve the plant-growth promoting potential of composting products. The results showed that the addition of IAA-producing bacteria promoted the assimilation of soluble salt, the condensation and aromatization of humus, and the accumulation of dissolved organic nitrogen (DON) and dissolved organic carbon (DOC). The bioaugmentation strategy also enabled faster microbial community succession during the medium-late phase of secondary fermentation. However, the colonization of Bacillus and Corynebacterium could not explain the disproportionate increase of IAA yield, which reached up to 5.6 times compared to the control group. Deeper analysis combined with physicochemical properties and microbial community structure suggested that IAA-producing bacteria might induce the increase of salinity, which enriched halotolerant bacteria capable of producing IAA, such as Halomonas, Brachybacterium and Flavobacterium. In addition, the results also proved that it was necessary to shorten secondary fermentation time to avoid IAA degradation without affecting composting maturity. In summary, enhancing secondary fermentation of composting via adding proper IAA-producing bacteria is an efficient strategy for upgrading the quality of organic fertilizer.

Perchlorate-reducing bacteria from Antarctic marine sediments.

Perchlorate is a contaminant that can persist in groundwater and soil, and is frequently detected in different ecosystems at concentrations relevant to human health. This study isolated and characterised halotolerant bacteria that can potentially perform perchlorate reduction. Bacterial microorganisms were isolated from marine sediments on Deception, Horseshoe and Half Moon Islands of Antarctica. The results of the 16S ribosomal RNA (rRNA) gene sequence analysis indicated that the isolates were phylogenetically related to Psychrobacter cryohalolentis, Psychrobacter urativorans, Idiomarina loihiensis, Psychrobacter nivimaris, Sporosarcina aquimarina and Pseudomonas lactis. The isolates grew at a sodium chloride concentration of up to 30% and a perchlorate concentration of up to 10,000 mg/L, which showed their ability to survive in saline conditions and high perchlorate concentrations. Between 21.6 and 40% of perchlorate was degraded by the isolated bacteria. P. cryohalolentis and P. urativorans degraded 30.3% and 32.6% of perchlorate, respectively. I. loihiensis degraded 40% of perchlorate, and P. nivimaris, S. aquimarina and P. lactis degraded 22%, 21.8% and 21.6% of perchlorate, respectively. I. loihiensis had the highest reduction in perchlorate, whereas P. lactis had the lowest reduction. This study is significant as it is the first finding of P. cryohalolentis and. P. lactis on the Antarctic continent. In conclusion, these bacteria isolated from marine sediments on Antarctica offer promising resources for the bioremediation of perchlorate contamination due to their ability to degrade perchlorate, showing their potential use as a biological system to reduce perchlorate in high-salinity ecosystems.

Production of lactobionic acid at high salt concentrations by Acinetobacter halotolerans isolated from seaside soil.

A lactobionic acid (LBA)-producing bacterium isolated from seaside soils was identified as Acinetobacter halotolerans and designated as strain KRICT-1. We determined whether KRICT-1 can produce LBA at high salt concentrations. The KRICT-1 strain grew on a nutrient broth (NB) agar plate with up to 7.0% NaCl, indicating high NaCl tolerance, and 30 °C was the optimum growth temperature for LBA production. We produced LBA using the KRICT-1 strain in NB medium containing various concentrations of NaCl. While Pseudomonas taetrolens, an efficient LBA-producing bacterium, could produce LBA with up to 5.5% NaCl, the KRICT-1 strain could produce LBA at up to 7.0% NaCl and produced more LBA than P. taetrolens with over 5.5% NaCl. We produced LBA using NB medium containing 7.0% NaCl by batch fermentation of the KRICT-1 strain in a 5 L fermenter. The LBA production titer and productivity of the KRICT-1 strain were 32.1 g/L and 0.22 g/L/h, respectively, which were approximately 1.35- and 1.38-fold higher than those (23.7 g/L and 0.16 g/L/h) obtained from flask culture. Additionally, quinoprotein glucose dehydrogenase is an LBA-producing enzyme in A. halotolerans. We demonstrated that the A. halotolerans KRICT-1 strain is appropriate for LBA production at high salt concentrations.

Investigating the effect of nanoparticle on phenanthrene biodegradation by Labedella gwakjiensis strain KDI.

Polycyclic aromatic hydrocarbons (PAHs), as persistent organic contaminants, are a major source of concern due to their toxic effect on ecosystems and human health. This study attempted to isolate halotolerant PAHs degrading bacteria from saline oil-contaminated soils. Among the isolates, strain KDI with the highest 16S rRNA gene sequence similarity to Labedella gwakjiensis was able to reduce surface tension (ST) from 65.42 to 26.60 mN m-1 and increase the emulsification index to 81.04%, as a result of significant biosurfactant production. Response Surface Methodology (RSM) analysis was applied to optimize the factors, i.e. PAHs concentration and NaCl concentration as well as to determine the effect of these important variables on PAHs biodegradation. The Carbon Quantum Dots. Iron Oxide (CQDs.Fe3O4) nanoparticles were characterized by several popular analytical techniques, after which the effect of CQD.Fe3O4 nanoparticles on biodegradation was examined. PAHs biodegradation rate and efficiency of strain KDI to degrade PHE in the presence of CQD.Fe3O4 nanoparticles was analyzed by GC. According to the results during biodegradation both the concentration of PAHs and the amount of NaCl were effective. The biodegradation rate significantly increased in the presence of CQD.Fe3O4. The highest biodegradation of PHE occurred in the presence of 0.5 g/L of CQD.Fe3O4 which was 63.63% and 81.77% after 48 and 72 h of incubation. To the best of our knowledge, this is the first report on optimization of PAHs concentration and salinity by RSM and nanobioremediation of PHE using a bacterial strain in the presence of CQD.Fe3O4 nanoparticles.

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).

Beyond Archaea: The Table Salt Bacteriome.

Commercial table salt is a condiment with food preservative properties by decreasing water activity and increasing osmotic pressure. Salt is also a source of halophilic bacteria and archaea. In the present research, the diversity of halotolerant and halophilic microorganisms was studied in six commercial table salts by culture-dependent and culture-independent techniques. Three table salts were obtained from marine origins: Atlantic Ocean, Mediterranean (Ibiza Island), and Odiel marshes (supermarket marine salt). Other salts supplemented with mineral and nutritional ingredients were also used: Himalayan pink, Hawaiian black, and one with dried vegetables known as Viking salt. The results of 16S rRNA gene sequencing reveal that the salts from marine origins display a similar archaeal taxonomy, but with significant variations among genera. Archaeal taxa Halorubrum, Halobacterium, Hallobellus, Natronomonas, Haloplanus, Halonotius, Halomarina, and Haloarcula were prevalent in those three marine salts. Furthermore, the most abundant archaeal genera present in all salts were Natronomonas, Halolamina, Halonotius, Halapricum, Halobacterium, Haloarcula, and uncultured Halobacterales. Sulfitobacter sp. was the most frequent bacteria, represented almost in all salts. Other genera such as Bacillus, Enterococcus, and Flavobacterium were the most frequent taxa in the Viking, Himalayan pink, and black salts, respectively. Interestingly, the genus Salinibacter was detected only in marine-originated salts. A collection of 76 halotolerant and halophilic bacterial and haloarchaeal species was set by culturing on different media with a broad range of salinity and nutrient composition. Comparing the results of 16S rRNA gene metataxonomic and culturomics revealed that culturable bacteria Acinetobacter, Aquibacillus, Bacillus, Brevundimonas, Fictibacillus, Gracilibacillus, Halobacillus, Micrococcus, Oceanobacillus, Salibacterium, Salinibacter, Terribacillus, Thalassobacillus, and also Archaea Haloarcula, Halobacterium, and Halorubrum were identified at least in one sample by both methods. Our results show that salts from marine origins are dominated by Archaea, whereas salts from other sources or salt supplemented with ingredients are dominated by bacteria.

Increasing salinity concentrations determine the long-term participation of methanogenesis and sulfidogenesis in the biodigestion of sulfate-rich wastewater.

The competition between sulfate-reducing bacteria (SRB) and methanogenic archaea (MA) depends on several factors, such as the COD/SO42- ratio, sensitivity to inhibitors and even the length of the operating period in reactors. Among the inhibitors, salinity, a characteristic common to diverse types of industrial effluents, can act as an important factor. This work aimed to evaluate the long-term participation of sulfidogenesis and methanogenesis in the sulfate-rich wastewater process (COD/SO42- = 1.6) in an anaerobic structured-bed reactor (AnSTBR) using sludge not adapted to salinity. The AnSTBR was operated for 580 d under mesophilic temperature (30 °C). Salinity levels were gradually increased from 1.7 to 50 g-NaCl L-1. Up to 35 g-NaCl L-1, MA and SRB equally participated in COD conversion, with a slight predominance of the latter (53 ± 11%). A decrease in COD removal efficiency associated with acetate accumulation was further observed when applying 50 g-NaCl L-1. The sulfidogenic pathway corresponded to 62 ± 17% in this case, indicating the inhibition of MA. Overall, sulfidogenic activity was less sensitive (25%-inhibition) to high salinity levels compared to methanogenesis (100%-inhibition considering the methane yield). The wide spectrum of SRB populations at different salinity levels, namely, the prevalence of Desulfovibrio sp. up to 35 g-NaCl L-1 and the additional participation of the genera Desulfobacca, Desulfatirhabdium, and Desulfotomaculum at 50 g-NaCl-1 explain such patterns. Conversely, the persistence of Methanosaeta genus was not sufficient to sustain methane production. Hence, exploiting SRB populations is imperative to anaerobically remediating saline wastewaters.

Halotolerant bacteria isolated from extreme environments induce seed germination and growth of chia (Salvia hispanica L.) and quinoa (Chenopodium quinoa Willd.) under saline stress.

The aim of the study was to characterize halotolerant bacteria and to evaluate their plant growth promotion potential on chia and quinoa seedlings under saline stress. Isolated microorganisms were evaluated for nitrogen fixation, phosphate solubilization, and production of siderophores and indole acetic acid. Three strains and two consortia were selected: Halomonas sp. (SFS), Micrococcus luteus (SA211), Bacillus sp. (HX11), C1 (SA211 + SFS), and C2 (SA211 + HX11). In vitro assays using water agar and half-strength Murashige-Skoog plates showed that an increase in salinity led to an increased seedlings mortality and a decrease in germination (lower than 40%), in total length (varying between 16% and 87% decreases), root length (from 60% to 92% lesser length) and dry weight (from 7% to 86% lower weight). Also, the relative growth index (RGI) decreased for both crops in most treatments, except those with HX11 and C2. These treatments had the highest growth parameters and RGI values in presence of high salinity in chia (50 and 100 mmol/L NaCl) and quinoa (200 and 400 mmol/L NaCl). SA211, the highest producer of indole acetic acid, showed a detrimental effect and anomalous phenotype on plants. Our results suggest that Bacillus sp. HX11, with multiple plant growth promotion traits and tolerance to saline stress, has a great potential as a bioinoculant in saline conditions and could be used as a biofertilizer for crop production.