Salt-tolerant plant growth-promoting bacteria as a versatile tool for combating salt stress in crop plants.

Soil salinization poses a great threat to global agricultural ecosystems, and finding ways to improve the soils affected by salt and maintain soil health and sustainable productivity has become a major challenge. Various physical, chemical and biological approaches are being evaluated to address this escalating environmental issue. Among them, fully utilizing salt-tolerant plant growth-promoting bacteria (PGPB) has been labeled as a potential strategy to alleviate salt stress, since they can not only adapt well to saline soil environments but also enhance soil fertility and plant development under saline conditions. In the last few years, an increasing number of salt-tolerant PGPB have been excavated from specific ecological niches, and various mechanisms mediated by such bacterial strains, including but not limited to siderophore production, nitrogen fixation, enhanced nutrient availability, and phytohormone modulation, have been intensively studied to develop microbial inoculants in agriculture. This review outlines the positive impacts and growth-promoting mechanisms of a variety of salt-tolerant PGPB and opens up new avenues to commercialize cultivable microbes and reduce the detrimental impacts of salt stress on plant growth. Furthermore, considering the practical limitations of salt-tolerant PGPB in the implementation and potential integration of advanced biological techniques in salt-tolerant PGPB to enhance their effectiveness in promoting sustainable agriculture under salt stress are also accentuated.

Exopolysaccharide production by salt-tolerant bacteria: Recent advances, current challenges, and future prospects.

Natural biopolymers derived from exopolysaccharides (EPSs) are considered eco-friendly and sustainable alternatives to available traditional synthetic counterparts. Salt-tolerant bacteria inhabiting harsh ecological niches have evolved a number of unique adaptation strategies allowing them to maintain cellular integrity and assuring their long-term survival; among these, producing EPSs can be adopted as an effective strategy to thrive under high-salt conditions. A great diversity of EPSs from salt-tolerant bacteria have attracted widespread attention recently. Because of factors such as their unique structural, physicochemical, and functional characteristics, EPSs are commercially valuable for the global market and their application potential in various sectors is promising. However, large-scale production and industrial development of these biopolymers are hindered by their low yields and high costs. Consequently, the research progress and future prospects of salt-tolerant bacterial EPSs must be systematically reviewed to further promote their application and commercialization. In this review, the structure and properties of EPSs produced by a variety of salt-tolerant bacterial strains isolated from different sources are summarized. Further, feasible strategies for solving production bottlenecks are discussed, which provides a scientific basis and direct reference for more scientific and rational EPS development.

Exopolysaccharide Produced by Pediococcus pentosaceus E8: Structure, Bio-Activities, and Its Potential Application.

The novel exopolysaccharide EPS-E8, secreted by Pediococcus pentosaceus E8, was obtained by anion-exchange and gel filtration chromatography. Structural analyses identified EPS-E8 as a heteropolysaccharide containing mannose, glucose, and galactose. Its major backbone consists of →2)-α-D-Manp-(1→2,6)-α-D-Glcp-(1→6)-α-D-Manp-(1→, and its molecular weight is 5.02 × 104 g/mol. Using atomic force microscopy and scanning electron microscopy, many spherical and irregular reticular-like shapes were observed in the microstructure of EPS-E8. EPS-E8 has outstanding thermal stability (305.7°C). Both the zeta potential absolute value and average particle diameter increased gradually with increasing concentration. Moreover, at a concentration of 10 mg/ml, the antioxidant capacities of, 1-Diphenyl-2-picrylhydrazyl (DPPH), ABTS and hydroxyl radical were 50.62 ± 0.5%, 52.17 ± 1.4%, and 58.91 ± 0.7%, respectively. EPS-E8 possesses excellent emulsifying properties against several food-grade oils, and its activity is retained under various conditions (temperature, pH, and ionic strength). Finally, we found that EPS-E8 as a polysaccharide-based coating could reduce the weight loss and malondialdehyde (MDA) content of strawberry, as well as preserving the vitamin C and soluble solid content during storage at 20°C. Together, the results support the potential application of EPS-E8 as an emulsifier, and a polysaccharide-based coating in fruit preservation.

Development and characterization of levan/pullulan/chitosan edible films enriched with ε-polylysine for active food packaging.

The levan/pullulan/chitosan edible films, enriched with ε-polylysine, as an antimicrobial agent, were successfully fabricated by the casting method, and their applicability for food packaging was systematically evaluated by several analytical techniques. An increase in the levan/pullulan ratios (ranged from 0:6 to 3:3) in the films showed a decreased water solubility (from 72.21% to 26.64%) and oxygen permeability (from 48.75 × 10-2 g·mm·m-2·d-1·kPa-1 to 4.45 × 10-2 g·mm·m-2·d-1·kPa-1), and increased elongation at break (from 10.92% to 46.61%). All the films showed a strong inhibitory effect on two typical food-borne pathogens and good biodegradability in the soil. These films were employed as edible coatings on strawberries, and the storage stability was investigated by means of physical and biochemical parameters. Compared to control, the weight loss, firmness, and total soluble solids of the coated strawberries showed a downward trend. Overall, these findings suggest that the developed edible films could be a potential approach for sustainable active food packaging.

High-expression and characterization of a novel serine protease from Ornithinibacillus caprae L9T with eco-friendly applications.

In the current work, a novel thermophilic serine protease gene (P3862) from Ornithinibacillus caprae L9T was functionally expressed in Bacillus subtilis SCK6. The monomeric enzyme of about 29 kDa was purified to homogeneity with 43.91% of recovery and 2.81-folds of purification. Characterization of the purified protease revealed the optimum activity at pH 7 and 65 °C. The protease exhibited excellent activity and stability in the presence of Na+, Mg2+, Ca2+, ethanediol, n-hexane, Tween-20, Tween-80 and Triton X-100. P3862 displayed favorable caseinolytic activity, moderate keratinolytic activity but no collagenolytic activity. Besides, the homology model of P3862 possessed a globular configuration and characteristic of α/ß hydrolase fold, and displayed stable interactions with casein, glycoprotein and keratin rather than collagen. Moreover, the crude enzyme could completely dehair goatskin within 6 h, resulting in decrease in BOD5, COD and TSS loads by 72.86, 74.07, and 73.79%, respectively, as compared with Na2S treatment. Biocatalytic applications revealed that it could effectively remove egg-stains from fabrics at 37 °C for 30 min with low supplementation (300 U/mL), and was able to degrade the feathers of duck and chicken. Overall, these outstanding properties make P3862 valuable in the development of environmentally friendly biotechnologies .

Optimization of fermentation conditions, purification and rheological properties of poly (γ-glutamic acid) produced by Bacillus subtilis 1006-3.

This study aimed to investigate the optimal fermentation condition, purification and rheological properties of extracellular polymers produced by Bacillus subtilis 1006-3. An optimum temperature of 30.2 °C, inoculation amount of 6.1%, and pH of 8.2 were determined via Response Surface Methodology. The result of amino acid analysis and gel electrophoresis indicated that the obtained polymer contained only glutamic acid, with a wide molecular weight range. This polymer was finally determined as γ-PGA by infrared spectroscopy. The γ-PGA solution displayed a behavior of pseudoplastic non-Newtonian fluid with shear thinning properties, which can be described by the Ostward-de Waele power law model. The apparent viscosity of γ-PGA solution increased with the increase in its concentration from 1% to 10%. The deviation in pH from neutral value, and the addition of NaCl or MgCl2 can reduce the apparent viscosity of γ-PGA solution, and it was more sensitive to Mg2+ than to Na+ addition. At the concentration of 4, 6, and 8%, γ-PGA solution showed predominantly viscous response in the range of 0.1-100 rad/s angular frequency (G″>G'). These results indicated the potential application of the γ-PGA as a thickening agent.

Exoproduction and Biochemical Characterization of a Novel Serine Protease from Ornithinibacillus caprae L9T with Hide-Dehairing Activity.

This study is the first report on production and characterization of the enzyme from an Ornithinibacillus species. A 4.2-fold increase in the extracellular protease (called L9T) production from Ornithinibacillus caprae L9T was achieved through the one-factor-at-a-time approach and response surface methodological optimization. L9T protease exhibited a unique protein band with a mass of 25.9 kDa upon sodium dodecyl sulfate-polyacrylamide gel electrophoresis. This novel protease was active over a range of pH (4-13), temperatures (30-80°C) and salt concentrations (0-220 g/l), with the maximal activity observed at pH 7, 70°C and 20 g/l NaCl. Proteolytic activity was upgraded in the presence of Ag+, Ca2+ and Sr2+, but was totally suppressed by 5 mM phenylmethylsulfonyl fluoride, which suggests that this enzyme belongs to the serine protease family. L9T protease was resistant to certain common organic solvents and surfactants; particularly, 5 mM Tween 20 and Tween 80 improved the activity by 63 and 15%, respectively. More importantly, L9T protease was found to be effective in dehairing of goatskins, cowhides and rabbit-skins without damaging the collagen fibers. These properties confirm the feasibility of L9T protease in industrial applications, especially in leather processing.

Characterization of Structural and Physicochemical Properties of an Exopolysaccharide Produced by Enterococcus sp. F2 From Fermented Soya Beans.

The present study sought to isolate a novel exopolysaccharide (EPS-F2) from Enterococcus sp. F2 through ethanol precipitation, anion-exchange, and gel-filtration chromatography and characterize the physicochemical properties by spectral techniques. EPS-F2 was identified as a neutral homo-exopolysaccharide composed of only glucose with a high molecular weight of 1.108 × 108 g/mol. It contained →6)-α-D-Glcp-(1→ linkage in the main chain and →3, 6)-α-D-Glcp-(1→ branch chain). Moreover, EPS-F2 possessed excellent thermal stability (266.6°C), water holding capacity (882.5%), oil holding capacity (1867.76%), and emulsifying activity against various edible oils. The steady shear experiments exhibited stable pseudo plasticity under various conditions (concentrations, temperatures, and pHs). The dynamic oscillatory measurements revealed that EPS-F2 showed a liquid-like behavior at a low concentration (2.5%), while a solid-like behavior at high concentrations (3.0 and 3.5%). Overall, these results suggest that EPS-F2 could be a potential alternative source of functional additives and ingredients and be applied in food industries.

Mechanism of Cr(VI) reduction by Lysinibacillus sp. HST-98, a newly isolated Cr (VI)-reducing strain.

Facing the increasingly severe Cr(VI) pollution, bioreduction has proved to be an eco-friendly remediation method. An isolated strain identified as Lysinibacillus can relatively reduce Cr(VI) well. Even if the concentration of Cr(VI) increased to 250mg/L, the strain HST-98 could also grow and remove Cr(VI) well. After optimization of reaction conditions, the optimal pH, temperature, and electron donor are 8~9, 36°C, and sodium lactate, respectively. Coexisting metal ions such as Cu2+, Co2+, and Mn2+ are beneficial to reduce Cr(VI), while Zn2+, Ni2+, and Cd2+ are just the opposite. What is more, the mechanism of the reduction by the strain HST-98 is chiefly mediated by intracellular enzymes. After gene sequence homology blast and analysis, the genes and enzymes related to chromium metabolism in strain HST-98 have been annotated, which helps us to further understand the reduction mechanism of the strain HST-98. In general, Lysinibacillus sp. HST-98 is a potential candidate to repair the Cr(VI)-contaminated sites.

Spatial distribution and morphological transformation of chromium with coexisting substances in tannery landfill.

The prosperity and development of tannery industry have brought about rapid economic growth. However, the tannery landfill without anti-seepage measures in the early stage has generated masses of environmental hazards owing to the lack of awareness in environmental protection. Therefore, it is imperative to pay much attention to the understanding of environmental hazards from tannery waste. In this study, solid samples and groundwater samples were collected from a tannery landfill to study the effect of the characteristic pollutants produced by tanning on chromium distribution with other coexisting substances. The results showed that significant correlations were demonstrated between multiple coexisting substances (total organic carbon, total petroleum hydrocarbons, total nitrogen, Cr, F, Ca, Cu and Pb), indicating the possible same source or they coming from the same tannery production stage. The weights of positive effects and negative effects of coexisting substances on total Cr distribution in the profile decreased in the order: total nitrogen > Cu > Ca > Pb > total organic carbon > F > SO42-> Cd, and Ni > Cl > Hg, respectively. Moreover, the simulation of Visual MINTEQ showed that the cations were mainly bound to Cr as CrO42-, while the anions were bound to Cr3+. This study provided a new perspective on the selection of remediation strategies for Cr-contaminated sites to avoid secondary environmental pollution caused by the release of coexisting heavy metals.

Structural elucidation and physicochemical characteristics of a novel high-molecular-weight fructan from halotolerant Bacillus sp. SCU-E108.

An exopolysaccharide, EPS-B108, was isolated from the fermented broth (with a yield of 11.3 g/L) of halotolerant Bacillus sp. SCU-E108 by ethanol precipitation, anion-exchange and gel-filtration chromatography, and well characterized by means of physical, chemical and spectral techniques. Data indicated that EPS-B108 was composed solely of fructose with a high molecular weight of 3.578 × 107 g/mol, and contained a ß-(2 â†’ 6)-linked d-Fruf backbone with a single ß-d-Fruf at C-1 position. An irregular saccular- or cake-like shape was observed under the enlarged view. It showed no acute oral toxicity in mice, and had good thermal stability (242 °C), solubility in water (91.3%) and oil-holding capacity (1717.0%). Steady-shear flow and dynamical viscoelasticity of aqueous EPS-B108 solutions varied with the polymer concentration, shear rate and temperature, and were described by the Power-law model. Together, these findings support the further application of EPS-B108 as an alternative source of functional food additives and ingredients.

Leucobacter chromiisoli sp. nov., isolated from chromium-containing chemical plant soil.

A Gram-stain-positive, rod-shaped, aerobic, non-motile, non-sporulating bacterial strain, designated CSA1T, was isolated from chromium-containing soil sampled at a chemical plant. Growth of strain CSA1T occurred at pH 6-10 (optimum, pH 7), 15-45 °C (optimum, 30 °C) and in the presence of 0.5-6.5 % (w/v) NaCl (optimum, 2 %). The 16S rRNA gene sequence of strain CSA1T revealed the highest similarity to Leucobacter ruminantium A2T (97.5 %), Leucobacter tardus K 70/01T (97.3 %), Leucobacter humi Re6T (96.6 %), Leucobacter kyeonggiensis F3-P9T (96.2 %), Leucobacter zeae CC-MF41T (96.1 %) and Leucobacter weissii S27T (96.0 %). The draft genome of CSA1T was approximately 3 350 931 bp in size with a G+C content of 70.6 mol%. The average nucleotide identity (ANI) and digital DNA-DNA hybridization (dDDH) values among strain CSA1T and the selected Leucobacter species were 74.0-79.2 % (ANIb), 84.3-87.1 % (ANIm) and 21.5-25.4 % (dDDH), which are below the recommended cutoff values for species delineation. The major fatty acids were anteiso-C15 : 0, iso-C16 : 0 and anteiso-C17 : 0. The polar lipids were diphosphatidylglycerol, phosphatidylglycerol and an unknown glycolipid. The predominant menaquinones were MK-11, MK-8 and MK-6. The cell-wall amino acids were 2,4-diaminobutyric acid, alanine, glycine, glutamic acid and threonine. From the phenotypic, chemotaxonomic and molecular features, strain CSA1T was considered to represent a novel species of the genus Leucobacter, for which the name Leucobacter chromiisoli sp. nov. is proposed. The type strain is CSA1T (=JCM 34359T=CGMCC 1.18746T).

Halomonas pellis sp. nov., a moderately halophilic bacterium isolated from wetsalted hides.

A Gram-stain-negative, moderately halophilic strain, designated strain L5T, was isolated from wetsalted hides collected from Chengdu, south-west PR China. The cells were motile, facultative aerobic, short rod-shaped and non-endospore-forming. Growth of strain L5T occurred at pH 6-10 (optimum, pH 8), 10-45 °C (optimum, 30 °C) and in the presence of 1-17 % (w/v) NaCl (optimum, 10 %). Results of phylogenetic analyses based on 16S rRNA, gyrB and rpoD gene sequences and its genome revealed that strain L5T belonged to the genus Halomonas. Strain L5T was found to be most closely related to the type strains of Halomonas saliphila, Halomonas lactosivorans, Halomonas kenyensis, Halomonas daqingensis and Halomonas desiderata (98.8, 98.6, 98.3, 97.9 and 97.4 % 16S rRNA gene sequence similarity, respectively). The draft genome was approximately 4.2 Mb in size with a G+C content of 63.5 mol%. The average nucleotide identity (ANI) and digital DNA-DNA hybridization values among strain L5T and the selected Halomonas species were 83.3-88.9 % (ANIm), 71.1-87.3 % (ANIb) and 20.2-34.6 %, which are below the recommended cutoff values. Major fatty acids were C16 : 0, C16 : 1 ω7c, C18 : 1 ω7c and C19 : 0 cyclo ω8c and the predominant ubiquinone was Q-9, with minor ubiquinone Q-8 also present. The phospholipid profile consisted of diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine, phosphatidylcholine, four unidentified aminophospholipids and three unidentified phospholipids. Based on the mentioned polyphasic taxonomic evidence, strain L5T represents a novel species within the genus Halomonas, for which Halomonas pellis sp. nov. is proposed. The type strain is L5T (=CGMCC 1.17335T=KCTC 72573T).

Genomic insights into the salt tolerance and cold adaptation of Planococcus halotolerans SCU63T.

Planococcus halotolerans, recently described as a novel species with SCU63T as the type strain, is capable of thriving in up to 15% NaCl and temperatures as low as 0 °C. To better understand its adaptation strategies at the genomic level, strain SCU63T was subjected to whole-genome sequencing and data mining. The high-quality assembly yielded 17 scaffolds with a genome size of 3,622,698 bp. Its genome harbors 3683 protein-coding sequences and 127 RNA genes, as well as three biosynthetic gene clusters and 25 genomic islands. The phylogenomic tree provided compelling insights into the evolutionary relationships of Planococcus. Comparative genomic analysis revealed key similarities and differences in the functional gene categories among Planococcus species. Strain SCU63T was shown to have diverse stress response systems for high salt and cold habitats. Further comparison with three related species showed the presence of numerous unique gene clusters in the SCU63T genome. The strain might serve as a good model for using extremozymes in various biotechnological processes.

Gracilibacillus salitolerans sp. nov., a moderate halophile isolated from saline soil in Northwest China.

A moderately halophilic strain, designated SCU50T, was recovered from a saline soil sample and characterized by a polyphasic approach. The 16S rRNA gene sequence analysis showed that strain SCU50T belonged to the genus Gracilibacillus and was most closely related to Gracilibacillus thailandensis TP2-8T (98.1 % similarity) and Gracilibacillus orientalis XH-63T (97.7 %). Genomic average nucleotide identity and digital DNA-DNA hybridization analyses confirmed the separate species status of the new isolate relative to other recognized Gracilibacillus species. The genome size was about 5.09 Mbp and the DNA G+C content was 36.7 mol%. The strain grew optimally at 10-15 % (w/v) NaCl, pH 6.5-7.5 and 25-30 °C. It contained anteiso-C15 : 0, iso-C15 : 0 and anteiso-C17 : 0 as the dominant fatty acids and menaquinone-7 as the major respiratory quinone. The polar lipid profile was examined and found to comprise diphosphatidylglycerol, phosphatidylglycerol, one unidentified phospholipid and one unidentified lipid. The cell-wall peptidoglycan type was A1γ based on meso-diaminopimelic acid. Combining the data from phenotypic, chemotaxonomic, genomic and phylogenetic characterization, it was concluded that strain SCU50T should be assigned as representing a novel species within the genus Gracilibacillus. Thus, a novel taxon named Gracilibacillus salitolerans sp. nov. was first established, with SCU50T (=CGMCC 1.17336T=KCTC 43107T) as the type strain.

Description of Salinicola corii sp. nov., a Halotolerant Bacterium Isolated from Wetsalted Hides.

A novel Gram-stain-negative, moderately halotolerant, rod-shaped bacterium, designated strain L3T, was isolated from a wetsalted hide in Chengdu, China. The organism grew optimally at 30 °C, at pH 8 and with 5-10% (w/v) NaCl. The major cellular fatty acids were C16:0, C16:1ω7c, C18:1ω7c and C19:0 cyclo ω8c; the predominant respiratory quinone was Q-9; the phospholipids consisted of diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylglycerol and three unidentified phospholipids. Phylogenetic trees based on the 16S rRNA, gyrB and rpoD genes' sequences, obtained using three different algorithms, clearly revealed the isolate belonged to the genus Salinicola, and was found to be closely related to Salinicola acroporae JCM 30412T, Salinicola socius CGMCC 1.12383T and Salinicola lusitanus CR50T. The draft genome was approximately 4.5 Mb in size with 4486 predicted coding sequences, and the G+C content was 62.6 mol%. The maximum values of ANI and dDDH between strain L3T and the three above-mentioned type species were 89.2% and 63.8%, respectively. Differential phenotypic properties, together with the genome analysis, support the view that strain L3T represents a novel species, Salinicola corii sp. nov., with the type strain L3T (=CGMCC 1.17272T=KCTC 72572T).

Preparation, characterization and functional properties of a novel exopolysaccharide produced by the halophilic strain Halomonas saliphila LCB169T.

A novel exopolysaccharide, designated hsEPS, was successfully prepared from the high-salt-fermented broth of a novel species Halomonas saliphila LCB169T by ethanol precipitation, anion-exchange and gel-filtration chromatography, and its structure was well-characterized by means of chemical and spectral analyses. Results showed that hsEPS was primarily composed of mannose and glucose with a relative weight-average molecular weight of 5.133 × 104 g/mol. It was deduced that the major backbone contained (1→2)-linked α-D-Manp and (1→6)-linked α-D-Manp with branches substituted at C-2 by T-α-D-Manp and at C-6 by the fragment of T-α-D-Manp-(1→2)-α-D-Manp-(1→. A sheet-like structure was observed under high magnification. The water solubility index, water holding capacity, oil holding capacity and foaming capacity of hsEPS were 98.0, 19.3, 1386.7 and 82.2%, respectively. It also exhibited outstanding emulsifying activity against all tested edible oils. Together, the resulted data indicated that hsEPS might serve as an active ingredient in food, cosmetics and detergents.

Ornithinibacillus caprae sp. nov., a moderate halophile isolated from the hides of a white goat.

A novel Gram-stain-positive, motile, moderate halophile, strain L9T, was isolated from hides of white goat in China. The isolate grew optimally at 30 °C, at pH 7 and with 5-10% (w/v) NaCl. The predominant menaquinone was MK-7, and the major cellular fatty acids were identified as iso-C15:0 and anteiso-C15:0. The peptidoglycan amino acid type was determined to be A4ß, containing L-ornithine and D-aspartic as diagnostic amino acids. The phospholipids were dominated by diphosphatidylglycerol, phosphatidylglycerol, one unidentified aminophospholipid and two unidentified phospholipids. Genome sequencing resulted in a genome size of 4.0 Mbp and a DNA G + C content of 35.9 mol%. Phylogenetic trees based on the 16S rRNA gene sequences showed the isolate to be closely related to Oceanobacillus limi H9BT (98.2% similarity) and Ornithinibacillus halophilus G8BT (97.5% similarity). The ANI and dDDH values between strain L9T and the closely related species were 69.8-76.1% and 13.0-20.5%, respectively. On the basis of the data presented, strain L9T represents a novel species of the genus Ornithinibacillus, for which the name Ornithinibacillus caprae sp. nov. is proposed. The type strain is L9T (= KCTC 43176T = CGMCC 1.17659T).

Draft genome sequence of Actinocorallia populi A251T, an actinomycetes producing polyketides and nonribosomal polypeptides.

In this work, we present the draft genome sequence of Actinocorallia populi A251T consisting of 8,253,402 bp with a G + C content of 71.5 mol%. The genome sequence includes 3 5S rRNA genes, 54 tRNA genes, 28 snRNA genes and 19 CRISPRs in 26 contigs. Using the Rapid Annotation using Subsystem Technology, a total of 7766 coding DNA sequences, which were assigned to 436 subsystems, were found in the genome. And 6743 protein-coding sequences with designated functions were assigned to 19 categories in the Cluster of Orthologous Groups database. The genome contains 20 gene clusters responsible for the synthesis of secondary metabolites, including two type I polyketide synthase (PKS) gene clusters, two type III PKS gene clusters, three nonribosomal peptide synthetase (NRPS) gene clusters and two hybrid PKS/NRPS gene clusters. These results indicate that strain A251 has the ability to produce several nonribosomal polypeptides and diverse polyketides, which was verified by liquid chromatography-mass spectrometry analysis of the extraction from fermentation broth. In addition, lactones, indole and many unknown natural products are present in the metabolites. Bioactivity testing revealed anticancer and antidiabetic activities of the crude extract towards the cancer cell line HepG2. In summary, the genomic sequences and bioactive fermentation products demonstrate the potential of strain A251 in biotechnology.

Structural characterization and functional evaluation of a novel exopolysaccharide from the moderate halophile Gracilibacillus sp. SCU50.

A novel exopolysaccharide (named mhEPS) with a molecular weight of 5.881 × 104 g/mol was isolated from Gracilibacillus sp. SCU50's high-salt fermentation broth by ethanol precipitation, anion-exchange and gel-filtration chromatography before being structurally characterized and functionally evaluated. mhEPS consists of mannose, galactose, glucose and fucose in a molar ratio of 90.81:5.76:2.22:1.21. The backbone of mhEPS was (1→3,6)-linked α-D-mannopyranose residues, branched by single α-D-mannopyranose units attached to the main chain at C-2 position of every residue. The water solubility index, water holding capacity and oil holding capacity of mhEPS were 93.53, 14.89 and 1023.34%, respectively. mhEPS showed to possess good emulsifying activity against all tested substrates, and it could potentially increase the high-salinity tolerance of strain SCU50. The lack of toxicity of mhEPS was also preliminarily determined. Due to the functional properties of mhEPS, it is a good candidate to develop as an active ingredient in food, cosmetics and detergents.