Overcoming the inhibitory effects of urea to improve the kinetics of microbial-induced calcium carbonate precipitation (MICCP) by Lysinibacillus sphaericus strain MB284.

Among different microbial-induced calcium carbonate precipitation (MICCP) mechanisms utilized for biomineralization, ureolysis leads to the greatest yields of calcium carbonate. Unfortunately, it is reported that urea-induced growth inhibition can delay urea hydrolysis but it is not clear how this affects MICCP kinetics. This study investigated the impact of urea addition on the MICCP performance of Lysinibacillus sphaericus MB284 not previously grown on urea (thereafter named bio-agents), compared with those previously cultured in urea-rich media (20 g/L) (hereafter named bio-agents+ or bio-agents-plus). While it was discovered that initial urea concentrations exceeding 3 g/L temporarily hindered cell growth and MICCP reactions for bio-agents, employing bio-agents+ accelerated the initiation of bacterial growth by 33% and led to a 1.46-fold increase in the initial yield of calcium carbonate in media containing 20 g/L of urea. The improved tolerance of bio-agents+ to urea is attributed to the presence of pre-produced endogenous urease, which serves to reduce the initial urea concentration, alleviate growth inhibition, and expedite biomineralization. Notably, elevating the initial concentration of bio-agents+ from OD600 of 0.01 to 1, housing a higher content of endogenous urease, accelerated the initiation of MICCP reactions and boosted the ultimate yield of biomineralization by 2.6 times while the media was supplemented with 20 g/L of urea. These results elucidate the advantages of employing bio-agents+ with higher initial cell concentrations to successfully mitigate the temporary inhibitory effects of urea on biomineralization kinetics, offering a promising strategy for accelerating the production of calcium carbonate for applications like bio self-healing of concrete.

Uranium removal in groundwater by Priestia sp. isolated from uranium-contaminated mining soil.

Priestia sp. WW1 was isolated from a uranium-contaminated mining soil and identified. The uranium removal characteristics and mechanism of Priestia sp. WW1 were investigated. The results showed that the removal efficiency of uranium decreased with the increase of initial uranium concentration. When the uranium initial concentration was 5 mg/L, the uranium removal efficiency achieved 92.1%. The increase of temperature could promote the uranium removal. Carbon source could affect the removal rate of uranium, which was the fastest when the methanol was used as carbon source. The solution pH had significant effect on the uranium removal efficiency, which reached the maximum under solution pH 5.0. The experimental results and FTIR as well as XPS demonstrated that Priestia sp. WW1 could remove uranium via both adsorption and reduction. The common chloride ions, sulfate ions, Mn(II) and Cu(II) enhanced the uranium removal, while Fe(III) depressed the uranium removal. The Priestia sp. WW1 could effectively remove the uranium in the actual mining groundwater, and the increase of initial biomass could improve the removal efficiency of uranium in the actual mining groundwater. This study provided a promising bacterium for uranium remediation in the groundwater.

Evansella halocellulosilytica sp. nov., an alkali-halotolerant and cellulose-dissolving bacterium isolated from bauxite residue.

An alkali and salt-tolerating strain FJAT-44876T was isolated from the bauxite residue sample. The 16S rRNA gene sequence and phylogenetic analysis suggest that strain FJAT-44876T was a member of the genus Evansella. It grew at 15-45 â„ƒ (optimum 20-25 â„ƒ) and pH 6.5-11.0 (optimum pH 8.0-9.0) with 0-20% (w/v) NaCl (optimum 6-8%). The major fatty acids were anteiso-C15:0, iso-C15:0, anteiso-C17:0, iso-C17:0, and C16:0. The cell wall peptidoglycan contained meso-diaminopimelic acid and MK-7 as the menaquinone. The major polar lipids were diphosphatidylglycerol, phosphatidylmethylethanolamine, phosphatidylethanolamine, and phosphatidylglycerol. The genomic DNA G+C content was 38.2%. The average nucleotide identity values between strain FJAT-44876T and closely related members were below the cutoff level for species delineation. Thus, based on the above results, strain FJAT-44876T represents a novel species of the genus Evansella, for which the name Evansella halocellulosilytica sp. nov., is proposed. The type strain is FJAT-44876T (=CCTCC AB 2016264T = DSM 104633T).

Rossellomorea arthrocnemi sp. nov., a novel plant growth-promoting bacterium used in heavy metal polluted soils as a phytoremediation tool.

Strain EAR8T is a root endophyte isolated from Arthrocnemum macrostachyum plants collected from the Odiel marshes, Huelva (Spain). It presented in vitro plant growth-promoting properties and improved the plant growth and heavy metal accumulation in polluted soils playing an important role in phytoremediation strategies. Phenotypically, strain EAR8T cells were Gram-positive, aerobic and non-motile rods with terminal oval endospores and non-swollen sporangia which form beige, opaque, butyrous, raised and irregular colonies with undulate margins. The strain was able to grow between 15-45 °C, at pH 6.0-9.0 and tolerated 0-25 % NaCl (w/v) showing optimal growth conditions on trypticase soy agar plates supplemented with 2.5 % NaCl (w/v) at pH 7.0 and 37 °C for 24 h. Chemotaxonomic analyses showed that the isolate has meso-diaminopimelic acid as the peptidoglycan in the cell wall and MK-7 as the major respiratory quinone. The predominant fatty acids were anteiso-C15 : 0 and iso-C15 : 0 and the polar lipid profile was composed of diphosphatidylglycerol, phosphatidylglycerol and phosphatidylethanolamine. Phylogenetic analyses based on the whole proteomes of closest sequenced relatives confirmed that strain EAR8T is affiliated to the genus Rossellomorea and forms a clade with Rossellomorea vietnamensis 15-1T with maximum support. Genome analyses showed that EAR8T has indole-3-acetic acid and siderophore biosynthesis and transporters genes and genes related to resistance against heavy metals. Phenotypic and phylogenomic comparative studies suggested that strain EAR8T is a new representative of the genus Rossellomorea and the name Rossellomorea arthrocnemi sp. nov. is proposed. Type strain is EAR8T (=CECT 9072T=DSM 103900T).

Nanoparticle-associated single step hydrogen fermentation for the conversion of starch potato waste biomass by thermophilic Parageobacillus thermoglucosidasius.

In the present study, starch-based potato peel waste biomass (PWB) was utilized as a potential substrate for hydrogen production via dark fermentation by the thermophillic amylase producing strain Parageobacillus thermoglucosidasius KCTC 33548. Supplementation of Fe3O4 nanoparticles (300 mg/L) led to a 4.15-fold increase in hydrogen production as compared to the control. The addition of optimized concentrations of both Fe3O4 nanoparticles (300 mg/L) and L-cysteine (250 mg/L) during hydrogen fermentation using pure starch and PWB generated maximum cumulative hydrogen yields of 167 and 71.9 mL with maximum production rates of 2.81 and 1.26 mL/h, respectively. Further, the correlation between Fe3O4 and the expression of hydrogenase isoforms and the related hydrogenase activity was explored. The possible mechanisms of the action of Fe3O4 on enhanced hydrogenase activity and hydrogen production was elucidated. To our knowledge, there are no such studies reported on enhanced hydrogen production from PWB in a single step.

Biological selenite removal and recovery of selenium nanoparticles by haloalkaliphilic bacteria isolated from the Nakdong River.

Microbial selenite reduction has increasingly attracted attention from the scientific community because it allows the separation of toxic Se from waste sources with the concurrent recovery of Se nanoparticles, a multifunctional material in nanotechnology industries. In this study, four selenite-reducing bacteria, isolated from a river water sample, were found to reduce selenite by > 85% within 3 d of incubation, at ambient temperature. Among them, strain NDSe-7, belonging to genus Lysinibacillus, can reduce selenite and produce Se nanospheres in alkaline conditions, up to pH 10.0, and in salinity of up to 7.0%. This strain can reduce 80 mg/L of selenite to elemental Se within 24 h at pH 6.0-8.0, at a temperature of 30-40 °C, and salinity of 0.1-3.5%. Strain NDSe-7 exhibited potential for use in Se removal and recovery from industrial saline wastewater with high alkalinity. This study indicates that extremophilic microorganisms for environmental remediation can be found in a conventional environment.

Genome-scale metabolic modeling of P. thermoglucosidasius NCIMB 11955 reveals metabolic bottlenecks in anaerobic metabolism.

Parageobacillus thermoglucosidasius represents a thermophilic, facultative anaerobic bacterial chassis, with several desirable traits for metabolic engineering and industrial production. To further optimize strain productivity, a systems level understanding of its metabolism is needed, which can be facilitated by a genome-scale metabolic model. Here, we present p-thermo, the most complete, curated and validated genome-scale model (to date) of Parageobacillus thermoglucosidasius NCIMB 11955. It spans a total of 890 metabolites, 1175 reactions and 917 metabolic genes, forming an extensive knowledge base for P. thermoglucosidasius NCIMB 11955 metabolism. The model accurately predicts aerobic utilization of 22 carbon sources, and the predictive quality of internal fluxes was validated with previously published 13C-fluxomics data. In an application case, p-thermo was used to facilitate more in-depth analysis of reported metabolic engineering efforts, giving additional insight into fermentative metabolism. Finally, p-thermo was used to resolve a previously uncharacterised bottleneck in anaerobic metabolism, by identifying the minimal required supplemented nutrients (thiamin, biotin and iron(III)) needed to sustain anaerobic growth. This highlights the usefulness of p-thermo for guiding the generation of experimental hypotheses and for facilitating data-driven metabolic engineering, expanding the use of P. thermoglucosidasius as a high yield production platform.

Bacteria incorporated with calcium lactate pentahydrate to improve the mortar properties and self-healing occurrence.

Concrete can be harmful to the environment due to its high energy consumption and CO2 emission and also has a potential crack formation, which can promote a drop in its strength. Therefore, concrete is considered as a non-sustainable material. The mechanisms by which bacterial oxidation of organic carbon can precipitate calcite that may fill the voids and cracks on cement-based materials have been extensively investigated to prevent and heal the micro-cracks formation. Hence, this study focused on utilizing a new alkaliphilic bacterial strain indigenous to an Indonesian site, Lysinibacillus sphaericus strain SKC/VA-1, incorporated with calcium lactate pentahydrate, as a low-cost calcium source, with various bacterial inoculum concentrations. The bacterium was employed in this study due to its ability to adapt to basic pH, thus improving the physical properties and rejuvenating the micro-cracks. Experimentally, the addition of calcium lactate pentahydrate slightly affected the mortar properties. Likewise, bacteria-incorporated mortar exhibited an enhancement in the physical properties of mortar. The highest improvement of mechanical properties (an increase of 45% and 36% for compressive and indirect tensile strength, respectively) was achieved by the addition of calcium lactate pentahydrate incorporated with 10% v/v bacterial inoculum [about 7 × 107 CFU/ml (colony-forming unit/ml)]. The self-healing took place more rapidly on bacterial mortar supplemented with calcium lactate pentahydrate than on the control specimen. XRD analysis demonstrated that the mineralogical composition of self-healing precipitates was primarily dominated by calcite (CaCO3), indicating the capacity of L. sphaericus strain SKC/VA-1 to precipitate calcite through organic carbon oxidation for self-healing the artificial crack on the mortar. To our knowledge, this is the first report on the potential utilization of the bacterium L. sphaericus incorporated with calcium lactate pentahydrate to increase the mortar properties, including its self-healing ability. However, further study with the water-cement ratio variation is required to investigate the possibility of using L. sphaericus and calcium lactate pentahydrate as an alternative method rather than reducing the water-cement ratio to enhance the mortar properties.

Efficacy of polyextremophilic Aeribacillus pallidus on bioprocessing of beet vinasse derived from ethanol industries.

This work aimed to evaluate the applicability of Aeribacillus pallidus for the aerobic treatment of the concentrated beet vinasse with high chemical oxygen demand (COD 685 g.L-1) that is defined as an environmental pollutant. This bacterium is a polyextremophilic strain and grow aerobically up to 7.5% vinasse at high temperature (50 °C). In the bioreactor and under controlled conditions, A. pallidus reduced the soluble COD content of 5% vinasse up to 27% during 48 h and utilized glucose and glycerol, completely. Furthermore, a reduction of manganese, copper, aluminum, and nickel concentrations was observed in the treated vinasse with A. pallidus. The obtained results make this strain as an appropriate alternative to be used for the aerobic bioprocessing of the vinasse.

The effect of bioaugmentation with Exiguobacterium sp. AO-11 on crude oil removal and the bacterial community in sediment microcosms, and the development of a liquid ready-to-use inoculum.

This study demonstrates the feasibility of using Exiguobacterium sp. AO-11 to remediate oil-contaminated environments. Bioaugmentation using AO-11 showed the best removal percentage, 75%, of 4% (w/w) crude oil in sediment microcosms in 100 days. In terms of the bacterial community structure during crude oil degradation, the addition of AO-11 did not change the indigenous bacterial community, while the addition of urea fertilizer induced structural shift of indigenous bacterial community. Exiguobacterium sp. AO-11 was developed as a bioremediation product, and a liquid formulation of AO-11 was developed. Coconut milk residue and soybean oil mill sludge were used for bacterial cultivation to reduce the production cost, and they could enhance bacterial cell growth. The liquid formulation of AO-11 prepared in phosphate buffer could be stored at 4 °C for at least 2 months, and it maintained efficacy in the treatment of crude oil-contaminated seawater. Overall, bioaugmentation with strain AO-11 could be an effective solution for the bioremediation of crude oil-contaminated environments.

Transcriptome profiling reveals the molecular processes for survival of Lysinibacillus fusiformis strain 15-4 in petroleum environments.

A bacterial strain designated Lysinibacillus fusiformis 15-4 was isolated from oil-free soil on the Qinghai-Tibet Plateau, which can grow well utilizing petroleum hydrocarbons as a carbon source at a lower temperature. To deeply characterize the molecular adaptations and metabolic processes of this strain when grown in a petroleum-containing environment, transcriptome analysis was performed. A total of 4664 genes and the expression of 3969 genes were observed in strain 15-4. When the strain was grown in petroleum-containing medium, 2192 genes were significantly regulated, of which 1312 (60%) were upregulated and 880 (40%) were downregulated. This strain degraded and adapted to petroleum via modulation of diverse molecular processes, including improvements in transporter activity, oxidoreductase/dehydrogenase activity, two-component system/signal transduction, transcriptional regulation, fatty acid catabolism, amino acid metabolism, and environmental stress responses. Many strain-specific genes were involved in the oxidation of hydrocarbon compounds, such as several luciferase family alkane monooxygenase genes, flavin-utilizing monooxygenase family genes, and flavoprotein-like family alkanesulfonate monooxygenase genes. Several cold shock protein genes were also induced suggesting adaptation to cold environments and the potential for petroleum degradation at low temperatures. The results obtained in this study may broaden our understanding of molecular adaptation of bacteria to hydrocarbon-containing environments and may provide valuable data for further study of L. fusiformis.

Biodegradation of aliphatic and polycyclic aromatic hydrocarbons by the thermophilic bioemulsifier-producing Aeribacillus pallidus strain SL-1.

The utilization of thermophilic hydrocarbon-degrading microorganisms is a suitable strategy for improving biodegradation of petroleum hydrocarbons and PAHs, as well as enhancing oil recovery from high-temperature reservoirs. In this study, the thermophilic strain Aeribacillus pallidus SL-1 was evaluated for the biodegradation of crude oil and PAHs at 60 °C. Strain SL-1 was found to preferentially degrade short-chain n-alkanes (

Enhancement the Cellulase Activity Induced by Endophytic Bacteria Using Calcium Nanoparticles.

The huge applications of cellulosic and lignocellulosic materials in the various fields of life lead to accumulation of its wastes that became one of the major sources of environmental pollution. In this study, a Gram-positive cellulose-decomposing endophytic bacterium (Chi-04) was isolated from medicinal plant Chiliadenus montanus which inhabitant Saint Catherine (Sinai) region in Egypt. The bacterial strain was identified based on the sequence analysis of 16S rRNA genes as Lysinibacillus xylanilyticus. This isolate was capable of degrading 58% of cellulosic filter paper (100 g/l) within 15 days of incubation. The soluble and reduced sugars were spectrophotometrically determined as cellulose decomposition metabolites. The bacterial isolate exhibited an obvious activity toward cellulase enzyme production. The maximum cellulase activity (0.18 U/min) was detected after 12 days of incubation while the maximum release of soluble sugars (11.85 mg/ml) was detected after 15 days of incubation. CaCl2 nanoparticles (100 nm) were chemically prepared to enhance the activity of the enzyme. The optimum concentration of CaCl2 nanoparticles that showed the highest activity of cellulase (0.3 mg/ml reduced sugar) was 0.6%. The bacterial isolates showed potential convert of cellulose into reducing sugars which could be used in several applications.

Two selenium tolerant Lysinibacillus sp. strains are capable of reducing selenite to elemental Se efficiently under aerobic conditions.

Microbes play important roles in the transport and transformation of selenium (Se) in the environment, thereby influencing plant resistance to Se and Se accumulation in plant. The objectives are to characterize the bacteria with high Se tolerance and reduction capacity and explore the significance of microbial origins on their Se tolerance, reduction rate and efficiency. Two bacterial strains were isolated from a naturally occurred Se-rich soil at tea orchard in southern Anhui Province, China. The reduction kinetics of selenite was investigated and the reducing product was characterized using scanning electron microscopy and transmission electron microscopy-energy dispersive spectroscopy. The bacteria were identified as Lysinibacillus xylanilyticus and Lysinibacillus macrolides, respectively, using morphological, physiological and molecular methods. The results showed that the minimal inhibitory concentrations (MICs) of selenite for L. xylanilyticus and L. macrolides were 120 and 220 mmol/L, respectively, while MICs of selenate for L. xylanilyticus and L. macrolides were 800 and 700 mmol/L, respectively. Both strains aerobically reduced selenite with an initial concentration of 1.0 mmol/L to elemental Se nanoparticles (SeNPs) completely within 36 hr. Biogenic SeNPs were observed both inside and outside the cells suggesting either an intra- or extracellular reduction process. Our study implied that the microbes from Se-rich environments were more tolerant to Se and generally quicker and more efficient than those from Se-free habitats in the reduction of Se oxyanions. The bacterial strains with high Se reduction capacity and the biological synthesized SeNPs would have potential applications in agriculture, food, environment and medicine.

Quorum sensing inhibitors from marine bacteria Oceanobacillus sp. XC22919.

In this study, three active compounds isolated from Oceanobacillus sp. XC22919 were identified as 2-methyl-N-(2'-phenylethyl) butyramide (1), 3-methyl-N-(2'-phenylethyl)-butyramide (2) and benzyl benzoate (3), and were first reported to exhibit the apparent quorum sensing inhibitory activities against C. violaceum 026 and P. aeruginosa. Compounds 1-3 inhibited violacein production of C. violaceum 026 by 10.5-55.7, 11.2-55.7, and 27.2%-95.7%, respectively, and inhibited pyocyanin production of P. aeruginosa by 1.7-50.8, 39.1-90.7, and 57.2%-98.7%, respectively. The azocasein-degrading proteolytic rates of P. aeruginosa were observed by 13.4-31.5, 13.4-28.8, and 11.3%-21.1%, respectively. With respect to elastase, the range of inhibition of activity of compounds 1-3 was 2.1-30.3, 4.2-18.2, and 8.9%-15.7%, respectively. Compounds 1 and 3 also showed a concentration-dependent attenuation in biofilm formation, with the maximum of 50.6% inhibition, and 37.7% inhibition at 100 µg/mL, respectively.

Pueribacillus theae gen. nov., sp. nov., isolated from Pu'er tea.

A novel bacterial strain, designated T8T, isolated from ripened Pu'er tea, was investigated by using a polyphasic taxonomic approach. Cells stained Gram-positive and were aerobic, sporogenous and rod-shaped with flagella. Phylogenetic analysis of 16S rRNA gene sequences revealed the strain belonged to the family Bacillaceae in the class Bacilli and represented an independent taxon separated from other genera. Strain T8T shared low levels of 16S rRNA gene sequence similarity (<94 %) to members of other genera in the family Bacillaceae and was most closely related to Bacillus composti SgZ-9T (93.3 % sequence similarity). The DNA G+C content of strain T8T was 40 mol%. The major fatty acids (>10 %) of strain T8T were iso-C15 : 0 and iso-C16 : 0. The strain had a cell-wall type A1γ peptidoglycan with meso-diaminopimelic acid as the diagnostic diamino acid. MK-7 (62 %), MK-6 (31 %) and MK-8 (7 %) were detected as the isoprenoid quinones. The predominant polar lipids were diphosphatidylglycerol, phosphatidylglycerol, phosphatidylmethylethanolamine and six unidentified phospholipids. On the basis of the polyphasic evidence presented, strain T8T is considered to represent a novel genus and species in the family Bacillaceae, for which we propose the name Pueribacillus theae gen. nov., sp. nov. The type strain is T8T (=CGMCC 1.15924T=KCTC 333888T).

Camelliibacillus cellulosilyticus gen. nov., sp. nov., a cellulose-degrading bacterium isolated from tea.

A Gram-stain-positive, oxidase- and catalase-positive, endospore-forming, aerobic, non-motile and rod-shaped bacterium (THG-YT1T) was isolated from green tea. Growth occurred at 10-40 °C (optimum, 25-30 °C), at pH 6-8 (optimum, 7) and at 0-2 % NaCl (optimum, 0 %). Based on 16S rRNA gene sequences, phylogenetic analyses showed that strain THG-YT1T formed a distinct lineage with respect to closely related genera in the family Bacillaceae. Strain THG-YT1T was most closely related to the genera within the families Pullulanibacillus, Scopulibacillus, Tuberibacillus and Caenibacillu, with levels of 16S rRNA gene sequence similarity to the type species of members of these genera of less than 95.0 %. The menaquinone was MK-7. The polar lipids were phosphatidylethanolamine, two unidentified aminophospholipids, two unidentified aminolipids and two unidentified glycolipids. The major fatty acids of strain THG-YT1T were C18 : 3ω7c and anteiso-C17 : 0. The cell-wall peptidoglycan type was A1γ with meso-diaminopimelic acid as the diagnostic diamino acid plus alanine and glutamic acid. The cell-wall sugar was glucose. The DNA G+C content of strain THG-YT1T was determined to be 53.5 mol%. Based on the data presented here, strain THG-YT1T represents a novel species of a new genus of the family Bacillaceae, for which the name Camelliibacillus cellulosilyticus gen. nov., sp. nov. is proposed. The type strain is Camelliibacillus cellulosilyticus THG-YT1T(=KACC 19471T=CGMCC 1.16306T).

Effects of plant- and animal-based high-fat diets on lipid storage and distribution in environmental bacteria-colonized gnotobiotic mice.

Different edible oils such as lard and soybean oil have been reported to interact with the gut microbiota, affecting host lipid metabolism. However, whether bacteria derived from the environment influence host lipid metabolism remains unclear. This study aimed to clarify the roles of environmental bacteria in host lipid storage and distribution with various edible oils. Gnotobiotic C57BL/6JNarl mice were inoculated with Lysinibacillus xylanilyticus and Paenibacillus azoreducens and then fed either a normal diet (LabDiet 5010, control group) or a diet containing 60% lard (L-group) or soybean oil (S-group) for 18 months. Interestingly, the S-group accumulated massive amounts of white adipose tissue compared to the L- and control groups, while the L-group displayed more hepatic steatosis and fatty droplets than the other groups. The expression of fatty acid synthase (FAS), hydroxymethylglutaryl-coenzyme A reductase (HMGCR), sterol regulatory element-binding protein 2 (SREBP2), and peroxisome proliferator-activated receptor gamma (PPARγ) in the livers of the L-group were markedly elevated compared to the S-group. FAS and PPARγ protein levels were also markedly elevated. However, there were no differences in the expression of the pro-inflammatory cytokines interleukin-6 and tumor necrosis factor-α between the groups. Our results suggest that environmental bacteria may affect host hepatic inflammation and lipid distribution in the presence of high-fat diets, with different effects depending on the fat type consumed.

Development of a highly efficient oil degumming process using a novel phosphatidylinositol-specific phospholipase C enzyme.

Enzymatic degumming using phospholipase C (PLC) enzymes may be used in environmentally friendly processes with improved oil recovery yields. In this work, phosphatidylinositol-specific phospholipase C (PIPLC) candidates obtained from an in silico analysis were evaluated for oil degumming. A PIPLC from Lysinibacillus sphaericus was shown to efficiently remove phosphatidylinositol from crude oil, and when combined with a second phosphatidylcholine and phosphatidylethanolamine-specific phospholipase C, the three major phospholipids were completely hydrolyzed, providing an extra yield of oil greater than 2.1%, compared to standard methods. A remarkably efficient fed-batch Escherichia coli fermentation process producing ∼14 g/L of the recombinant PIPLC enzyme was developed, which may facilitate the adoption of this cost-effective oil-refining process.

Molecular identification of indigenous manganese solubilising bacterial biodiversity from manganese mining deposits.

Manganese (Mn) ranks twelfth among the most exuberant metal present in the earth's crust and finds its imperative application in the manufacturing steel, chemical, tannery, glass, and battery industries. Solubilisation of Mn can be performed by several bacterial strains which are useful in developing environmental friendly solutions for mining activities. The present investigation aims to isolate and characterize Mn solubilising bacteria from low grade ores from Sanindipur Manganese mine of Sundargh district in Odisha state of India. Four morphologically distinct bacterial strains showing visible growth on Mn supplemented plates were isolated. Mn solubilising ability of the bacterial strains was assessed by visualizing the lightening of the medium appearing around the growing colonies. Three isolates were gram negative and rod shaped while the remaining one was gram positive, coccobacilli. Molecular identification of the isolates was carried out by 16S rRNA sequencing and the bacterial isolates were taxonomically classified as Bacillus anthrasis MSB 2, Acinetobacter sp. MSB 5, Lysinibacillus sp. MSB 11, and Bacillus sp. MMR-1 using BLAST algorithm. The sequences were deposited in NCBI GenBank with the accession number KP635223, KP635224, KP635225 and JQ936966, respectively. Manganese solubilisation efficiency of 40, 96, 97.5 and 48.5% were achieved by MMR-1, MSB 2, MSB 5 and MSB 11 respectively. The efficiency of Mn solubilisation is suggested with the help of a pH variation study. The results are discussed in relation to the possible mechanisms involved in Manganese solubilisation efficiency of bacterial isolates.