Genomic Insights into Pediococcus pentosaceus ENM104: A Probiotic with Potential Antimicrobial and Cholesterol-Reducing Properties.

Pediococcus pentosaceus, which often occurs in fermented foods, is characterized by numerous positive effects on the human health, such as the presence of possible probiotic abilities, the reduction of cholesterol levels, satisfactory antimicrobial activity, and certain therapeutic functions. This study was conducted with the goal of describing the genomic content of Pediococcus pentosaceus ENM104, a strain known for its inhibitory effects against pathogenic bacteria and its remarkable probiotic potential, including the induction of significant reductions in cholesterol levels and the production of γ-aminobutyric acid (GABA). The P. pentosaceus ENM104 chromosome is circular. The chromosome is 1,734,928 bp with a GC content of 37.2%. P. pentosaceus also harbors a circular plasmid, pENM104, that is 71,811 bp with a GC content of 38.1%. Functional annotations identified numerous genes associated with probiotic traits, including those involved in stress adaptation (e.g., heat stress: htpX, dnaK, and dnaJ), bile tolerance (e.g., ppaC), vitamin biosynthesis (e.g., ribU, ribZ, ribF, and btuD), immunomodulation (e.g., dltA, dltC, and dltD), and bacteriocin production (e.g., pedA). Notably, genes responsible for lowering cholesterol levels (bile salt hydrolase, bsh) and GABA synthesis (glutamate/GABA antiporter, gadC) were also identified. The in vitro assay results using cell-free supernatants of P. pentosaceus ENM104 revealed antibacterial activity against carbapenem-resistant bacteria, such as Pseudomonas aeruginosa, Klebsiella pneumoniae, and Acinetobacter baumannii, and the inhibition zone diameter increased progressively over time. This comprehensive study provides valuable insights into the molecular characteristics of P. pentosaceus ENM104, emphasizing its potential as a probiotic. Its notable cholesterol-lowering, GABA-producing, and antimicrobial capabilities suggest promising applications in the pharmaceutical and food industries. Future research should focus on further exploring these functional properties and assessing the strain's efficacy in clinical settings.

Probiogenomic analysis of Lactiplantibacillus plantarum SPS109: A potential GABA-producing and cholesterol-lowering probiotic strain.

Lactiplantibacillus plantarum SPS109, an isolated strain of lactic acid bacteria (LAB) from fermented foods, showed remarkable potential as a probiotic with dual capabilities in γ-aminobutyric acid (GABA) production and cholesterol reduction. This study employs genomic and comparative analyses to search into the strain's genetic profile, safety features, and probiotic attributes. The safety assessment reveals the absence of virulence factors and antimicrobial resistance genes, while the genome uncovers bacteriocin-related elements, including sactipeptides and a cluster for putative plantaricins, strengthening its ability to combat diverse pathogens. Pangenome analysis revealed unique bacteriocin-related genes, specifically lcnD and bcrA, distinguishing SPS109 from four other L. plantarum strains producing GABA. In addition, genomic study emphasizes SPS109 strain distinctive features, two GABA-related genes responsible for GABA production and a bile tolerance gene (cbh) crucial for cholesterol reduction. Additionally, the analysis highlights several genes of potential probiotic properties, including stress tolerance, vitamin production, and antioxidant activity. In summary, L. plantarum SPS109 emerges as a promising probiotic candidate with versatile applications in the food and beverage industries, supported by its unique genomic features and safety profile.

Effects of Probiotic Fermented Fruit Juice-Based Biotransformation by Lactic Acid Bacteria and Saccharomyces boulardii CNCM I-745 on Anti-Salmonella and Antioxidative Properties.

Fermentation is an effective process for providing various beneficial effects in functional beverages. Lactic acid bacteria and yeast fermentation-based biotransformation contribute to enhancement of nutritional value and digestibility, including lactose intolerance reduction and control of infections. In this study, the probiotic fermented fruit juice (PFJ) was produced by Lactobacillus plantarum TISTR 1465, Lactobacillus salivarius TISTR 1112, and Saccharomyces boulardii CNCM I-745 while mixed fruit juice (MFJ) was used as the basic medium for microorganism growth. The potential function, the anti-salmonella activity of PFJ, was found to be effective at 250 mg/ml of MIC and 500 mg/ml of MBC. Biofilm inhibition was performed using the PFJ samples and showed at least 70% reduction in cell attachment at the MIC concentration of Salmonella Typhi DMST 22842. The antioxidant activities of PFJ were determined and the results revealed that FSB.25 exhibited 78.40 ± 0.51 mM TE/ml by FRAP assay, while FPSB.25 exhibited 3.44 ± 0.10 mM TE/ml by DPPH assay. The volatile compounds of PFJ were characterized by GC-MS, which identified alcohol, aldehyde, acid, ester, ketone, phenol, and terpene. The most abundant organic acid and alcohol detected in PFJ were acetic acid and 2-phenylethanol, and the most represented terpene was ß-damascenone. The sensory attributes showed scores higher than 7 on a 9-point hedonic scale for the FPB.25, illustrating that it was well accepted by panelists. Taken together, our results showed that PFJ could meet current consumer demand regarding natural and functional, fruit-based fermented beverages.

Exopolymeric substance from Bacillus velezensis P1 as an antifungal additive in chitosan coating to prolong the shelf life of mangoes.

Bacillus velezensis P1 inhibits various phytopathogenic fungi. Its exopolymeric substance (EPS) was active against Colletotrichum sp. at a minimum inhibitory concentration (MIC) of 6.25 mg/ml. EPS was added to chitosan from squid pen to produce an antifungal film coating. The addition of EPS at its MIC had no effect on the color of the chitosan film. Two components showed good compatibility and the tensile strength of the film was higher than that of neat chitosan film. Mangoes were treated with six different coatings, including the two films. Fruits coated with the films showed the lowest weight loss and prolonged shelf life of mangoes to three times the shelf life of controls (water and 2 % citric acid, w/v) and completely inhibited fungal infection. Film coatings of chitosan, alone or combined with the EPS from B. velezensis P1, showed potential to prolong the shelf life of ripe mangoes and decrease postharvest losses.

Complete Genome Sequence of Weissella cibaria NH9449 and Comprehensive Comparative-Genomic Analysis: Genomic Diversity and Versatility Trait Revealed.

Lactic acid bacteria (LAB) in the genus Weissella spp. contain traits in their genome that confer versatility. In particular, Weissella cibaria encodes several beneficial genes that are useful in biotechnological applications. The complete genome of W. cibaria NH9449 was sequenced and an in silico comparative analysis was performed to gain insight into the genomic diversity among members of the genus Weissella. A total of 219 Weissella genomes were used in a bioinformatics analysis of pan-genomes, phylogenetics, self-defense mechanisms, virulence factors, antimicrobial resistance, and carbohydrate-active enzymes. These investigations showed that the strain NH9449 encodes several restriction-modification-related genes and a CRISPR-Cas region in its genome. The identification of carbohydrate-active enzyme-encoding genes indicated that this strain could be beneficial in biotechnological applications. The comparative genomic analysis reveals the very high genomic diversity in this genus, and some marked differences in genetic variation and genes among Weissella species. The calculated average amino acid identity (AAI) and phylogenetic analysis of core and accessory genes shows the possible existence of three new species in this genus. These new genomic insights into Weissella species and their biological functions could be useful in the food industry and other applications.

Film coating based on native starch and cationic starch blend improved postharvest quality of mangoes.

This work focused on the preparation and characterization of films and coatings based on native cassava starch cationic cassava starch and a blend of the two. The films and coatings are intended for application as coating materials for mango fruits. Due to the good miscibility between native cassava starch and cationic cassava starch, the starch blend film was more hydrophobic than films produced from unblended native cassava starch and unblended cationic cassava starch. In addition, after storage for 10 days, the mangoes coated with the starch blend film had lost the least weight and exhibited only slight changes in physical appearance. Therefore, the coating of native and cationic cassava starch blend is a promising alternative coating that presents no hazard to consumer health or the environment.

Culture optimization to enhance carotenoid production of a selected purple nonsulfur bacterium and its activity against acute hepatopancreatic necrosis disease-causing Vibrio parahaemolyticus.

Purple nonsulfur bacteria (PNSB) were investigated for their carotenoid production and anti-vibrio activity against acute hepatopancreatic necrosis disease (AHPND)-causing Vibrio parahaemolyticus. To test carotenoid production, selected strains were cultivated in basic isolation medium (BIM), glutamate acetate medium, G5 medium and artificial acetic acid wastewater (AAW) medium. From 144 PNSB, Rhodopseudomonas palustris KTSSG46 was selected to produce carotenoids under microaerobic light conditions in BIM. When the culture medium was optimized, strain KTSSG46 grown in BIM modified with l-glutamate at 1 g/L more effectively inhibited AHPND-causing V. parahaemolyticus strains than standard BIM with 1 g/L (NH4 )2 SO4 . BIM was further modified with 1.23 g/L MgSO4 ·7H2 O and carotenoid production increased 40.22%. Carotenoid production at day 2 by strain KTSSG46 grown in BIM modified with l-glutamate at 1 and 1.23 g/L MgSO4 ·7H2 O was the same as production in BIM modified with monosodium glutamate (MSG). Culture supernatants from all BIM formulations showed similar activity against the resistant AHPND strain SR2. Based on high-performance liquid chromatography, carotenoids of strain KTSSG46 might be canthaxanthin. Grown in BIM modified with MSG, strain KTSSG46 could produce inexpensive carotenoids and release anti-vibrio compounds that, applied as shrimp feed additive, would prevent AHPND strains.

In silico comparative genomics analysis of Lactiplantibacillus plantarum DW12, a potential gamma-aminobutyric acid (GABA)-producing strain.

Gamma-aminobutyric acid (GABA) is an amino that plays a major role as a neurotransmitter. It iscommonly produced by lactic acid bacteria (LAB) naturally found in fermented food and fruit. Lactiplantibacillus plantarum DW12 is a high potential GABA-producing strain isolated from a fermented beverage. In this study, to highlight its ability to produce GABA, we sequenced the genome of L. plantarum DW12 and then performed comprehensive bioinformatics and meta-analysis to compare the genomic data of previously published genomes. Also, the evolutionary analysis among L. plantarum species was demonstrated using pan-genome analysis against 576 genomes from the database. As a result, the DW12 genome comprises one circular chromosome of 3,217,574 bp. It contains several genes that encode for the production of antimicrobial compounds including plantaricin A, E, F, J, K, and N. The glutamic acid decarboxylase (GAD) operon was found in the DW12 genome, suggests a high potential of producing GABA in this strain. Therefore, L. plantarum DW12 could be a good candidate as a starter culture in the beverage and food industries due to its safety aspects and ability to produce GABA.

Dietary supplementation with probiotic Rhodobacter sphaeroides SS15 extract to control acute hepatopancreatic necrosis disease (AHPND)-causing vibrio parahaemolyticus in cultivated white shrimp.

Cultivation of Penaeus vannamei (Pacific white shrimp) is faced with the serious problem of acute hepatopancreatic necrosis disease (AHPND), caused by Vibrio parahaemolyticus that carries plasmids containing binary toxin genes. The disease is typically moderated by the use of antibiotics. To investigate the control of AHPND and maintenance of water quality without the use of antibiotics, the supplementation of shrimp feed with anti-vibrio compounds from a crude extract of probiotic Rhodobacter sphaeroides SS15 was evaluated. The experimental design comprised four treatments: two that were challenged with AHPND-causing V. parahaemolyticus SR2 at a density of 6.0 × 105 cells mL-1 and two that were not challenged. The unchallenged groups comprised a control group that received commercial feed only (CF) and a group that received CF supplemented with 0.27% (w/w) of the extract of R. sphaeroides SS15 (modified CF: MCF). The treatments challenged with V. parahaemolyticus SR2 comprised a challenge group that received CF only (challenge CF: CF-SR2) and a challenge group that received modified CF (challenge MCF: MCF-SR2). V. parahaemolyticus SR2 was inoculated at the start of cultivation and at day 48 at the same cell density. No significant difference in growth performance was found among all treatments. All water quality parameters were better in the two treatments that received modified CF but excess nitrite, due to overfeeding in low salinity (5-8 ppt), caused shrimp mortality in all treatments. Vibrio populations were much higher in the CF treatments than in the modified CF treatments. After the first challenge, the survival rate was about 67% in both the CF-SR2 and MCF-SR2 treatments, compared with approximately 83% in the unchallenged treatments. One day after the second challenge, mortality in the CF-SR2 treatment was 100%, whereas 16.67% survived in the MCF-SR2 treatment. The survival rate was roughly 27% higher in the MCF treatment than in the CF treatment. The hepatopancreas and gut of both modified CF treatments showed no sign of AHPND. Via better water quality and trained immunity, the anti-vibrio compounds in the modified CF have great potential to increase the survival of cultivated shrimp infected with AHPND-causing strain SR2.

Biogas production by co-digestion of municipal wastewater and food waste: Performance in semi-continuous and continuous operation.

Municipal wastewater has recently attracted interest in relation to anaerobic wastewater treatments. Biogas production with co-digestion of mixed substrates has been proposed and has many potential benefits for municipal wastewater. The aim of this research was to assess the performance of biogas production during co-digestion of municipal wastewater and food waste under semi-continuous and continuous operation with various hydraulic retention times (HRTs). A laboratory-scale continuous stirred tank reactor (CSTR) at room temperature operation (27-32°C) was employed in this research. The highest methane yields of 167.41 ± 66.52, 194.35 ± 85.44, and 214.81 ± 85.44 ml/g-Vs were found in semi-continuous mode, respectively, at 30, 10, and 10 days of HRTs with a 10:90 ratio of municipal wastewater to food waste (based on TS). Result finding of optimum condition (10 days of HRTs) presented a methane yield of 485.58 ± 82.35 ml/g with continuous operation. Hence, food waste has practical implications for use as a co-substrate with the optimization condition of HRT and operation mode for biogas production from municipal wastewater. PRACTITIONER POINTS: Food waste has good potential for use as a co-substrate for biogas production from municipal wastewater. HRT reduction from 30 to 10 days in semi-continuous, biogas production from municipal wastewater and food waste increased by 59%. Co-digestion of municipal wastewater and food waste with continuous mode and 10 days of HRT was the effective biogas production.

Genomic Insight into Pediococcus acidilactici HN9, a Potential Probiotic Strain Isolated from the Traditional Thai-Style Fermented Beef Nhang.

Pediococcus acidilactici HN9 is a beneficial lactic acid bacterium isolated from Nhang, a traditional Thai-style fermented beef. In this study, the molecular properties of P. acidilactici HN9 were characterized to provide insights into its potential probiotic activity. Specifically, this work sought to report the complete genome of P. acidilactici HN9 and perform a comparative genome analysis with other bacterial strains belonging to the genus Pediococcus. Genomic features of HN9 were compared with those of all other bacterial Pediococcus strains to examine the adaptation, evolutionary relationships, and diversity within this genus. Additionally, several bioinformatic approaches were used to investigate phylogenetic relationships, genome stability, virulence factors, bacteriocin production, and antimicrobial resistance genes of the HN9 strain, as well as to ensure its safety as a potential starter culture in food applications. A 2,034,522 bp circular chromosome and two circular plasmids, designated pHN9-1 (42,239-bp) and pHN9-2 (30,711-bp), were detected, and used for pan-genome analysis, as well as for identification of bacteriocin-encoding genes in 129 strains belonging to all Pediococcus species. Two CRISPR regions were identified in P. acidilactici HN9, including type II-A CRISPR/CRISPR-associated (Cas). This study provides an in-depth analysis on P. acidilactici HN9, facilitating a better understanding of its adaptability to different environments and its mechanism to maintain genome stability over time.

Anti-Streptococcus mutans and anti-biofilm activities of dextranase and its encapsulation in alginate beads for application in toothpaste.

BACKGROUND: The accumulation of plaque causes oral diseases. Dental plaque is formed on teeth surfaces by oral bacterial pathogens, particularly Streptococcus mutans, in the oral cavity. Dextranase is one of the enzymes involved in antiplaque accumulation as it can prevent dental caries by the degradation of dextran, which is a component of plaque biofilm. This led to the idea of creating toothpaste containing dextranase for preventing oral diseases. However, the dextranase enzyme must be stable in the product; therefore, encapsulation is an attractive way to increase the stability of this enzyme. METHODS: The activity of food-grade fungal dextranase was measured on the basis of increasing ratio of reducing sugar concentration, determined by the reaction with 3, 5-dinitrosalicylic acid reagent. The efficiency of the dextranase enzyme was investigated based on its minimal inhibitory concentration (MIC) against biofilm formation by S. mutans ATCC 25175. Box-Behnken design (BBD) was used to study the three factors affecting encapsulation: pH, calcium chloride concentration, and sodium alginate concentration. Encapsulation efficiency (% EE) and the activity of dextranase enzyme trapped in alginate beads were determined. Then, the encapsulated dextranase in alginate beads was added to toothpaste base, and the stability of the enzyme was examined. Finally, sensory test and safety evaluation of toothpaste containing encapsulated dextranase were done. RESULTS: The highest activity of the dextranase enzyme was 4401.71 unit/g at a pH of 6 and 37 °C. The dextranase at its MIC (4.5 unit/g) showed strong inhibition against the growth of S. mutans. This enzyme at 1/2 MIC also showed a remarkable decrease in biofilm formation by S. mutans. The most effective condition of dextranase encapsulation was at a pH of 7, 20% w/v calcium chloride and 0.85% w/v sodium alginate. Toothpaste containing encapsulated dextranase alginate beads produced under suitable condition was stable after 3 months of storage, while the sensory test of the product was accepted at level 3 (like slightly), and it was safe. CONCLUSION: This research achieved an alternative health product for oral care by formulating toothpaste with dextranase encapsulated in effective alginate beads to act against cariogenic bacteria, like S. mutants, by preventing dental plaque.

Optimization of Fungal Dextranase Production and Its Antibiofilm Activity, Encapsulation and Stability in Toothpaste.

Dextranase catalyzes the degradation of the substrate dextran, which is a component of plaque biofilm. This enzyme is involved in antiplaque accumulation, which can prevent dental caries. The activity of crude dextranase from Penicillium roquefortii TISTR 3511 was assessed, and the maximum value (7.61 unit/g) was obtained at 37 °C and pH 6. The Plackett-Burman design was used to obtain significant factors for enhancing fungal dextranase production, and three influencing factors were found: Dextran, yeast extract concentration and inoculum age. Subsequently, the significant factors were optimized with the Box-Behnken design, and the most suitable condition for dextranase activity at 30.24 unit/g was achieved with 80 g/L dextran, 30 g/L yeast extract and five day- old inoculum. The use of 0.85% alginate beads for encapsulation exhibited maximum dextranase activity at 25.18 unit/g beads, and this activity was stable in toothpaste for three months of testing. This study explored the potential production of fungal dextranase under optimal conditions and its encapsulation using alginate for the possibility of applying encapsulated dextranase as an additive in toothpaste products for preventing dental caries.

Upgrading industrial effluent for agricultural reuse: effects of digestate concentration and wood vinegar dosage on biosynthesis of plant growth promotor.

Emphasis on water reuse in agricultural sector receives a renewed interest to close the loop in circular economy, especially in dry and water-stressed regions. In this work, wastewater from cooperative smoked sheet rubber factory and the effluent (digestate) from its treatment system (anaerobic digester) were used as medium to grow purple non-sulfur bacteria (PNSB), Rhodopseudomonas palustris strain PP803, with wood vinegar supplement at mid-log growth phase to stimulate the release of 5-aminolevulinic acid (ALA), a plant growth promotor. Wastewater-to-digestate ratios (D:W) represented by soluble chemical oxygen demand (SCOD) were found to influence both the growth of R. palustris and synthesis of ALA. The highest ALA release of 16.02 ± 0.75 µM and the biomass accumulation of 1302 ± 78 mg/L were obtained from the medium SCOD of 4953 mg/L. Although retarding biomass accumulation by 28-36%, wood vinegar (WV) addition was proven to improve ALA release by 40%. Result suggested that SCOD of 3438 mg/L (75:25 D:W) contained sufficient carbon source for PNSB growth and was chosen to subsequently run the photo-bioreactor (PBR) to sustain R. palustris PP803 cells production. In continuous PBR operation, PNSB proliferation suffered from the low organic concentration in PBR at low organic loading. An organic loading increase to 1.21 g COD/L day was found to attain highest biomass concentration and longest PNSB dominant period over microalgea. In this study, a real-time monitoring protocol of PNSB and microalgae was specifically developed based on image color analysis at acceptable accuracy (R2 = 0.94). In the final assay, verification of the PBR-grown inoculant was conducted and ALA release efficiency was discussed under various wood vinegar dosages and dosing frequencies. This work has advanced our understandings closer to practical field application.

Organic acids and 2,4-Di-tert-butylphenol: major compounds of Weissella confusa WM36 cell-free supernatant against growth, survival and virulence of Salmonella Typhi.

BACKGROUND: Salmonella Typhi (S. Typhi), the causative agent of typhoid fever, causes serious systemic disease in humans. Antibiotic treatment is required for the S. Typhi infection, while the inappropriate use of antibiotics causes increased drug-resistant S. Typhi. Hence, alternative therapies through non-antibiotic approaches are urgently needed. The use of beneficial lactic acid bacterium and/or its metabolites to control typhoid fever represent a promising approach, as it may exert protective actions through various mechanisms. METHOD: In this study, the cell-free culture supernatant (CFCS) of Weissella confusa WM36 was evaluated via the antibacterial activity, and its metabolites were identified. In addition, the effects of CFCS on Salmonella virulence behaviors were also investigated. RESULT: Based on strong inhibition the growth of S. Typhi DMST 22842, organic acids (lactic acid and acetic acid) and 2,4-Di-tert-butylphenol (2,4 DTBP), were the main antibacterial metabolites presented in CFCS of strain WM36. Minimum inhibitory concentration (MIC) at 40% WM36-CFCS dramatically reduced the S. Typhi population to more than 99.99% at 4 h and completely inhibited biofilm formation, while sub-MIC at 20% (v/v) and MIC could reduce 100% of motility. Additionally, sub-MIC at only 10% (v/v) WM36-CFCS did down-regulate the expression of virulence genes which are responsible for the type-III secretion system, effector proteins, and quorum sensing system in this pathogen. CONCLUSION: W. confusa WM36 and its metabolites are shown to be a promising candidates, and an effective approach against typhoid Salmonella burden.

Cell-free supernatants from cultures of lactic acid bacteria isolated from fermented grape as biocontrol against Salmonella Typhi and Salmonella Typhimurium virulence via autoinducer-2 and biofilm interference.

BACKGROUND: Salmonella Typhi and Salmonella Typhimurium are the causative pathogens of salmonellosis, and they are mostly found in animal source foods (ASF). The inappropriate use of antibiotics enhances the possibility for the emergence of antibiotic resistance in pathogens and antibiotic residue in ASF. One promising alternative to antibiotics in animal farming is the use of lactic acid bacteria (LAB). METHODS: The present study was carried out the cells and/or the cell-free culture supernatants (CFCS) from beneficial LAB against S. Typhi and S. Typhimurium. The antibacterial mechanisms of LAB-CFCS as biocontrol agents against both Salmonella serovars were investigated through the analysis of anti-salmonella growth activity, biofilm inhibition and quorum quenching activity. RESULTS: Among 146 LAB strains isolated from 110 fermented food samples, the 2 strong inhibitory effect strains (WM33 and WM36) from fermented grapes against both Salmonella serovars were selected. Out of the selected strains, WM36 was the most effective inhibitor, which indicated S. Typhi by showing 95.68% biofilm inhibition at 20% biofilm inhibition concentration (BIC) and reduced 99.84% of AI-2 signaling interference. The WM33 was the best to control S. Typhimurium by producing 66.46% biofilm inhibition at only 15% BIC and 99.99% AI-2 signaling a reduction. The 16S rDNA was amplified by a polymerase chain reaction (PCR). The selected isolates were identified as Weissella viridescens WM33 and Weissella confusa WM36 based on nucleotide homology and phylogenetic analysis. CONCLUSION: The metabolic extracts from Weissella spp. inhibit Salmonella serovars with the potential to be used as biocontrol agents to improve microbiological safety in the production of ASF.

Simultaneous bioprecipitation of cadmium to cadmium sulfide nanoparticles and nitrogen fixation by Rhodopseudomonas palustris TN110.

This study investigated the abilities of a purple non-sulfur bacterium, Rhodopseudomonas palustris TN110 to bioremediate cadmium through the biosynthesis of CdS nanoparticles and to fix nitrogen simultaneously. Under microaerobic-light conditions, R. palustris TN110 synthesized CdS nanoparticles. The produced CdS nanoparticles had a spherical shape and an average size of 4.85 nm. The Fourier transform infrared spectrum of the nanoparticles reveals the carbonyl groups, bending vibrations of the amide I and II bands of proteins, and CN stretching vibrations of aromatic and aliphatic amines. These bands and groups suggest protein capping/binding on the surface of the nanoparticles. R. palustris TN110 converted 25.61% of 0.2 mM CdCl2 to CdS nanoparticles under optimal conditions (pH 7.5, 30 °C and 3000 lux). The half maximal inhibitory concentration (IC50) value of the produced CdS nanoparticles was 1.76 mM. The produced CdS nanoparticles at IC50 up-regulated two genes associated with nitrogen fixation: Mo-Fe nitrogenase gene (nifH) and V-Fe nitrogenase gene (vnfG) at 2.83 and 2.27 fold changes, respectively. On the contrary, the produced CdS nanoparticles slightly down-regulated Fe-Fe nitrogenase gene (anfG). The amounts of ammonia released by the strain support the gene expression results. R. palustris TN110 has great potential to serve concurrently as a cadmium bioremediation agent and a nitrogen fixer. The strain could be beneficial to paddy fields that are contaminated with Cd through run off from mining and chemical fertilizer applications.

Arenibacillus arenosus gen. nov., sp. nov., a member of the family Rhodobacteraceae isolated from sea sand.

A Gram-stain-negative, aerobic, non-motile, non-spore-forming, rod-shaped bacterial strain, designated CAU 1304T, was isolated from sea sand. Strain CAU 1304T grew optimally at pH 8.5 and 30 °C and in the presence of 1 % (w/v) NaCl. Phylogenetic analysis based on 16S rRNA gene sequences revealed that strain CAU 1304T belonged to the family Rhodobacteraceae, and was most closely related to Roseicitreum antarcticum ZS2-28T (96.54 % similarity) and Rhodobacter veldkampii ATCC 35703T (96.46 %). The major fatty acid was C18 : 1ω7c and the respiratory quinone was Q-10. The polar lipids were composed of phosphatidylglycerol, phosphatidylcholine and an unidentified aminolipid. The DNA G+C content was 55.9 mol%. On the basis of phenotypic, chemotaxonomic and phylogenetic analysis, it is proposed that strain CAU 1304T represents a novel species of a new genus of the family Rhodobacteraceae, for which the name Arenibacillus arenosus gen. nov., sp. nov. is proposed. The type strain of Arenibacillus arenosus is CAU 1304T (=KCTC 42827T=NBRC 113022T).

Reduction in arsenic toxicity and uptake in rice (Oryza sativa L.) by As-resistant purple nonsulfur bacteria.

This study aimed to investigate the potential of Rhodopseudomonas palustris C1 and Rubrivivax benzoatilyticus C31 to ameliorate As toxicity and to reduce As uptake in rice. Strain C1 was superior to strain C31 for siderophore production. The mixed culture (1: 1) was most effective in reducing the toxicity of As species [As(III) and/or As(V), each 30 mg/l] by yielding maximal germination index that related to α- and ß-amylase activities in two Thai rice cultivars (HomNil: HN and PathumThani 1: PT). Arsenic toxicity to the seed germination followed the order: mixed As species > As(III) > As(V); and the toxicity was reduced in inoculated sets, particularly with a mixed culture. The mixed culture significantly enhanced rice growth under As stress in both rice cultivars as indicated by an increase in the production of chlorophyll a and b, and also supporting the non-enzymatic (carotenoids, lipid oxidation, and nitric oxide) and enzymatic (superoxide dismutase, ascorbate peroxidase, catalase, and glutathione reductase) activities. These were concomitant with productions of 5-aminolevulinic acid, indole-3-acetic acid, exopolymeric substances, and siderophores which significantly reduced As accumulation in treated rice. It can be concluded that the mixed culture has great potential to ameliorate rice from As toxicity by preventing As species entry into rice for enhancing rice growth and also for reducing As accumulation to produce safe rice from rice grown in contaminated paddy fields.

Sphingomicrobium arenosum sp. nov., isolated from marine sediment.

A Gram-stain-negative, strictly aerobic, motile by one single flagellum, dark-orange pigmented and rod-shaped bacterial strain, designated CAU 1457T, was isolated from marine sediment in the Republic of Korea and its taxonomic position was investigated by using a polyphasic approach. The isolate grew optimally at 30 °C, at pH 6.0 and in the presence of 2 % (w/v) NaCl. Based on 16S rRNA gene sequences similarity, strain CAU 1457T belonged to the genus Sphingomicrobium and was related most closely to Sphingomicrobium astaxanthinifaciens JCM 18551T (98.2 % similarity). Strain CAU 1457T contained ubiquinone-10 as the predominant isoprenoid quinone and 11-methyl C18 : 1ω7c and summed feature 8 (C18 : 1ω7c/ω6c) as the major cellular fatty acids. Triamine sym-homospermidine was detected as the major compound in the polyamine pattern. The polar lipids consisted of diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine, sphingoglycolipid, four unidentified glycolipids, one unidentified aminophospholipid, two unidentified phospholipids, one unidentified aminolipid and one unidentified lipid. DNA-DNA relatedness between strain CAU 1457T and the closely related strains, Sphingomicrobium astaxanthinifaciens JCM 18551T and Sphingomicrobium aestuariivivum KCTC 42286T were 32.7 and 28.4 %, respectively. The DNA G+C content of strain was 68.8 mol%. The phenotypic, chemotaxonomic and phylogenetic data indicated that strain CAU 1457T represents a novel species of the genus Sphingomicrobium, for which the name Sphingomicrobium arenosum sp. nov. is proposed. The type strain is CAU 1457T (=KCTC 62233T=NBRC 113094T).