Highest Exopolysaccharide Production Research Articles

Production and biological activities of exopolysaccharides synthesized by thermophilic bacilli isolated from hot springs in Türkiye.

Thermophilic bacteria able to produce exopolysaccharides (EPSs) have become attractive in recent years. EPSs synthesized by thermophiles are worth investigating due to their unexplored structural and biological properties. In this study, EPSs from thermophilic, Gram-positive bacterial isolates were purified and tested for their biological activities. A total of one hundred seven thermophilic bacteria were screened for their ability to produce exopolysaccharides. Nine isolates belonging to Geobacillus, Parageobacillus, Aeribacillus, and Anoxybacillus genera with highest EPS production were chosen, and purified EPSs (20, 61, 74, 76, 78, 89, 106, 134, and 261) were used for biological activity studies. EPS yields of selected thermophilic bacteria ranged between 117 and 419mg/L. Among the tested EPSs, 61, 106, and 261 showed antibacterial effect against E. faecalis JH2-2 at a final concentration of 1.5mg/mL. EPS samples had significantantioxidant capacity, especially EPS 134, with the highest DPPH radical scavenging activity of 100% at a concentration of 5mg/mL and the strongest reducing power.EPS 20 showed the highest lipid peroxidation inhibition effect at a rate of 31%. EPSs displayed weak alpha-amylase inhibition activity when compared with standard acarbose. The prebiotic indices of EPSs 20, 61, 76, 89, 134, and 261 were found to be higher than that of inulin, a representative prebiotic carbohydrate for all tested lactic acid bacteria in the study. All examined EPSs inhibited the biofilms formed by various bacteria depending on the test strain. Results indicated that thermophilic EPSs had remarkable antioxidant, prebiotic, and antibiofilm activities. Therefore, EPSs characterized in this study may have technological applications in health and food fields.

Metabolomics analysis based on UHPLC-QTOF-MS/MS to explore the synthesis mechanism and culture conditions optimization of Penicillium EF-2 exopolysaccharide

Penicillium exopolysaccharide (EPS) inhibits galactose lectins and enhances immunity. However, EPS production is low and its synthesis mechanism remains unclear. Penicillium EF-2 strains with high EPS production were selected for this study, and Penicillium fermentation conditions were subsequently improved. The optimal culture conditions were 30 g/L lactose, 6 g/L yeast extract powder, 4 d seed age, 10 % inoculation amount, 3 d of secondary fermentation time, and the final EPS yield was 3.97 g/L. UHPLC-Q-TOF-MS/MS was used to explore the mechanism of EPS synthesis at the metabolic level. Optimal carbon source: lactose and optimal nitrogen source: yeast extract can provide precursors for EPS synthesis through related metabolic pathways. Moreover, regulating the energy, vitamin, and lipid metabolic pathways created favourable conditions for EPS synthesis and secretion. These findings explain the mechanism of EPS synthesis at the metabolic level and provide a theoretical basis for optimising and industrialising EPS production.

Bio-Prospecting Xylose-Utilizing, Exopolysaccharide (EPS)-Producing Bacteria and EPS Quantification through Submerged Fermentation using Xylose as the Major Carbon Source

Study’s Novelty/ Excerpt This study identified bacterial isolates from diverse environments capable of utilizing xylose for exo-polysaccharide (EPS) production, an area with limited prior research. Potential EPS producers were isolated and identified as Staphylococcus, Enterobacter, Kocuria, Klebsiella, Enterococcus, Serratia, and Burkholderia species using a salt-based medium with xylose as the primary carbon source. The highest EPS production was observed in Enterobacter cloacae D1, E. cloacae D2, Klebsiella oxytoca D2, and K. oxytoca G1, ranging from 0.04 g/L to 2.0 g/L, highlighting these isolates' potential for optimization and application in various industries. Full Abstract Many microorganisms are capable of producing Exo-polysaccharides (EPS) while utilizing simple sugars and hexoses. These EPS found applications in various fields, such as agricultural biotechnology, pharmaceuticals, textiles, and food industries. However, there is a lack of studies on EPS-elaborating bacteria that can utilize pentoses like xylose. Therefore, the utilization of alternative carbon sources for EPS production has become a focus of recent research. This study aimed to prospect bacteria that can utilize xylose for EPS production. Samples from agricultural soil, dump sites, saline soil, cement-contaminated soil, fresh cow milk, cow dung, and yogurt were serially diluted and cultured in a salt-based medium with xylose as the primary carbon source. Slimy and mucoid colonies were selected as potential EPS-producing isolates and identified morphologically and biochemically using the VITEK 2 Automated identification system. The quantification of EPS production by these isolates was conducted through submerged fermentation with xylose as the sole carbon source. The mean heterotrophic bacterial count of xylose-utilizing bacteria ranged from 2.1x106 CFU to 3.5x108 CFU per gram of the samples analyzed. The slimy and mucoid colonies were identified as members of the genera Staphylococcus, Enterobacter, Kocuria, Klebsiella, Enterococcus, Serratia, and Burkholderia. The quantities of EPS produced by the isolates ranged from 0.04 g/L to 2.0 g/L, with E. cloacae D1, E. cloacae D2, K. oxytoca D2, and K. oxytoca G1 elaborating the highest amount of EPS. Bacterial isolates capable of utilizing xylose for EPS production were obtained from various sources, showing potential for further optimization

Physiological properties evaluation and exopolysaccharide biosynthesis of Limosilactobacillus fermentum JL-2 from Chinese traditional fermented dairy product based on genomic insight

Limosilactobacillus fermentum JL-2 with high production of exopolysaccharide (EPS) was screened from the traditional fermented dairy product in Xinjiang district (China) in our previous work. In this study, the whole genome of L. fermentum JL-2 was sequenced and the genomic information and function were studied to excavate its genotype, safety and probiotic properties. The safety evaluation in vitro showed that L. fermentum JL-2 was not hemolytic, sensitive to common antibiotics, and it had a weak biogenic amine production capacity. The genes related to EPS biosynthesis and their relationship with EPS production were discussed. The EPS production of L. fermentum JL-2 was 553.6 mg/L. The genome of L. fermentum JL-2 consisted of a circular 1.98 Mbp chromosome. A variety of genes related to probiotic properties such as acid tolerance, bile salt tolerance, adhesion to gut mucosa and environmental stress resistance were contained. A complete EPS gene cluster was found in the genome of L. fermentum JL-2, and the genes related to EPS biosynthesis such as epsA and epsB were found in L. fermentum JL-2. It is worth noting that EPS biosynthesis protein (gene0099) seemed to play a key role in the EPS synthesis of L. fermentum JL-2. These results revealed the potential of L. fermentum JL-2 as a probiotic at the gene level. Therefore, this study laid a theoretical foundation for further research into its potential probiotic function and its application in practice.

Effect of biogenic exopolysaccharides in characteristics and stability of a novel Requeson-type cheese

Whey is a by-product of the dairy industry with considerable nutritional value but tends to be discarded with industrial effluents. One of the alternatives for its use is the production of whey cheeses, although they need to add extra ingredients to raise the yields, which elevates production costs. A less expensive alternative is using exopolysaccharides (EPS), carbohydrate polymers microorganisms produce. This research aimed to formulate and evaluate the stability of a Requeson-type cheese employing whey that has EPS produced biogenically by in situ fermentation with lactic acid bacteria. Two EPS-producing strains, Lactobacillus delbrueckii subsp bulgaricus NCFB 2772 and Streptococcus thermophilus SY-102, were used separately and in coculture (1:1 ratio). We found that coculture had the highest EPS production (1.49 mg/mL of whey) compared to the monocultures. This influenced the yield of the processed Requeson-type cheese (5.56%), which was higher than the produced with unfermented whey (3.77%). Similarly, the physicochemical and sensory parameters of the developed product showed differences. Furthermore, none of the Requeson-type cheeses made with fermented whey showed microbial growth after 21 days of storage (4 °C). Therefore, EPS is a potential strategy for producing Requeson-type whey cheeses with a high yield and stability.

New strategy for bioplastic and exopolysaccharides production: Enrichment of field microbiomes with cyanobacteria

Seven photosynthethic microbiomes were collected from field environmental samples to test their potential in polyhydroxybutyrate (PHB) and exopolysaccharides (EPS) production, both alternatives to chemical-based polymers. Microscope observations together with microbial sequence analysis revealed the microbiome enrichment in cyanobacteria after culture growth under phosphorus limitation. PHB and EPS production were studied under three culture factors (phototrophy, mixotrophy and heterotrophy) by evaluating and optimizing the effect of three parameters (organic and inorganic carbon and days under light:dark cycles) by Box-Behnken design. Results showed that optimal conditions for both biopolymers synthesis were microbiome-dependent; however, the addition of organic carbon boosted PHB production in all the tested microbiomes, producing up to 14 %dcw PHB with the addition of 1.2 g acetate·L−1 and seven days under light:dark photoperiods. The highest EPS production was 59 mg·L−1 with the addition of 1.2 g acetate·L−1 and four days under light:dark photoperiods. The methodology used is suitable for enriching microbiomes in cyanobacteria, and for testing the best conditions for bioproduct synthesis for further scale up.

Screening and genome analysis of lactic acid bacteria with high exopolysaccharide production and good probiotic properties

Exopolysaccharide (EPS) is a biological polymer produced by lactic acid bacteria (LAB) with various health-beneficial biological activities, such as hypoglycemic, antioxidant, hypocholesterolemic, and immune-regulatory effects. As a food-grade material, EPS could be used directly in food processing and production. In this study, 48 laboratory-preserved LAB strains were screened for high exopolysaccharide production, the best five of which were M-1 (0.90 g/L), M-2 (0.79 g/L), MY04 (1.15 g/L), M-5 (0.85 g/L) and M-7 (0.75 g/L). The prebiotic properties of these five strains were compared and MY04 had the best overall properties, with good resistance to acid, bile salts, and simulated gastrointestinal fluid, strong antibacterial activity and high intestinal adhesion capacity. Whole genome sequence analysis of virulence factors and drug resistance genes, determined that Lactiplantibacillus plantarum MY04 is safe for human consumption and a promising probiotic candidate for development of novel functional foods.

Exopolysaccharides of lactic acid bacteria isolated from honeybee gut and effects of their antibiofilm activity against Streptococcus mutans.

Streptococcus mutans is one of the main factors in formation of cariogenic biofilms. New strategies need to be developed to reduce the formation of cariogenic biofilms. For this purpose, bacterial exopolysaccharides (EPS) could be considered as new agents against biofilms. Therefore, cell-bound (b-EPS) and released exopolysaccharides (r-EPS) were extracted from the strains Apilactobacillus kunkeei K1.10 and Latilactobacillus curvatus Kar.9b isolated from the microbiota of honeybees, and their antibiofilm effects on S. mutans biofilm formation were determined. The highest reduction in biofilm formation was achieved by r-EPS of L. curvatus Kar.9b and A. kunkeei K1.10. Scanning electron micrographs (SEM) showed that r-EPS inhibited biofilm formation by reducing adhesion of S. mutans. To increase the production of r-EPS from A. kunkeei K1.10, the effects of different incubation conditions were also analyzed. The highest EPS production was obtained during 48 h-incubation at 37ºC in a medium containing 1% fructose. r-EPS can be used as a raw material to inhibit cariogenic biofilms. Further studies revealing the detailed structural analysis of r-EPS and the mechanism of action of its antibiofilm effect could be beneficial. Finally, b-EPS and r-EPS from lactic acid bacteria were found to have very different properties in terms of their antibiofilm properties.

Exopolysaccharide (EPS) Producing Bacteria of Sundarbans Mangrove Forest Soil

The present study was undertaken to investigate the exopolysaccharide (EPS) producing bacteria from Sundarbans Mangrove Forest (SMF) soil of Bangladesh. The pH and aerobic heterotrophic bacterial counts of the soil samples ranged from 5.83 to 7.77 and 0.87 × 107 to 7.2 × 107 cfu/g, respectively. Potential 18 EPS producing bacterial isolates were selected for detailed study among which 15 were provisionally identified as members of the genus Bacillus, 2 were recognized as Dinococcus sp. and another one as Micrococcus sp. The genus Bacillus includes 7 distinct species viz. B. stearothermophilus, B. subtilis, B. brevis, B. marinus, B. schlegelli, B. pumilus and B. globisporous. The highest EPS production was found in the LB medium. The pHs of 6.5-7.5, 0% salinity, and 37°C temperature were found to be optimum for better growth of EPS producing bacteria. The three EPS producing bacterial isolates i.e. B. pumilus, B. globisporus and B. strearothermophilus were further confirmed through 16S rDNA sequence analysis. The culture and sensitivity (C/S) test results revealed streptomycin (S 10) as the most effective antibiotic to control the tested bacterial isolates. Plant Tissue Cult. & Biotech. 32(2): 145-156, 2022 (December)

Characterization of plant growth promoting rhizobacterial strain Bacillus cereus with special reference to exopolysaccharide production

Exo-polysaccharides (EPS) possess unique water holding and cementing properties that help in soil aggregation. EPS also increase nutrient uptake in plants, increase water flow across the roots, reduce saline stress by up taking Na+ from soil and increases plant resistance to drought stress. All these factors lead to investigate for eco-friendly and economically reasonable sources of exo-polysaccharides. The exo-polysaccharides secreted by bacteria might play potential role in improvement of agricultural productivity. In the present study, seven bacterial isolates from rice rhizosphere were characterized for their plant growth promoting traits. The isolate NP6 showed most promising results with indole-3-acetic acid production, phosphate solubilization, hydrogen cyanide production, ammonia production, nitrogen fixation along with significant amount of exo-polysaccharides production. The strain was identified as Bacillus cereus by 16S rDNA sequencing method. The co-inoculation of NP6 with pathogenic fungal strain Alternaria alternata showed 86% inhibition of the mycelial growth. For NP6, fructose and peptone were proved to be most optimum carbon and nitrogen sources respectively for exo-polysaccharide production. At a C/N ratio of 20, highest exo-polysaccharides production was observed. In presence of salinity stress NP6 is also able to secrete considerable amount of EPS. All these properties of NP6 make it a candidate to be utilized in large scale exo-polysaccharides production as well as bio-inoculant for improvement of soil condition.

Determination of probiotic properties of lactic acid bacteria and yeasts isolated from three lacto‐fermented cereals mixed with whey, citrus, and tomato pomace

This study tested the probiotic activities of bacteria and yeast isolates from three lacto-fermented cereal (LFC) products which were earlier shown high probiotic efficacy in farm animals. LFC products were freshly produced by solid-state fermentation using fresh whey without a starter culture. LFCa is a mixture of barley, whey, citrus pomace, LFCb of rye, whey, citrus pomace, and tomato pomace and LFCc of LFCb with an addition of ground thyme leaves at the end of fermentation. Six bacteria and two yeast species were isolated from LFC products and tested for probiotic activities. Candida spp and Saccharomyces spp exhibited low probiotic activities. However, lactic acid bacteria (LAB) isolates, namely, Lactobacillus plantarum O33, Pediococcus pentosaceus 10, Lactobacillus paracasei spp. paracasei O54, Enterococcus spp., Lactococcus lactis spp. lactis O3, and Lactobacillus curvatus O32 had overall high survival rates of 76% at pH 4.0, 95% at pH 5.0, 70% at 0.30% of bile salt, high exopolysaccharide production of 85 to 150 mg/L, acceptable aggregation rates of 19% of 4 h co-aggregation with E. coli and 25% auto-aggregation, high inhibition zones of 11 to 20 mm in diameter of pathogens and resistance to three antibiotics. Multivariate tests showed that Enterococcus spp. was the one with the highest probiotic efficacy. In conclusion, these LFC products can be used as probiotic supplements. Novelty impact statement This study determined the probiotic activity of bacteria and yeasts isolated from lacto-fermented cereals, previously shown to have high efficacy in animal studies. Yeast isolates exhibited low probiotic abilities, while six lactic acid bacteria isolated exhibited strong probiotic properties. Enterococcus spp. was found with the highest probiotic activities. The results showed that the products or isolated bacteria strains can safely be used in food and feed applications for health benefits.

Isolation, characterization and anti-UVB irradiation activity of an extracellular polysaccharide produced by Lacticaseibacillus rhamnosus VHPriobi O17

The purpose of this study was to isolate exopolysaccharides (EPS) from lactic acid bacteria (LAB) and evaluate EPS anti-UVB viability. Lacticaseibacillus rhamnosus VHPriobi O17 with high EPS production was screened from 34 strains of LAB. The EPS (OP-2) produced by L. rhamnosus VHPriobi O17 was purified by alcohol precipitation and DEAE-μSphere anion exchange chromatography. By ion chromatography, FT-IR spectrum and gel column chromatography, EPS (OP-2) was a novel Man-like polysaccharide with the weight-averaged molecular of 84.2 kDa. The EPS (OP-2) can effectively alleviate HaCaT cells apoptosis and overproduction of reactive oxygen species (ROS) induced by UVB. The results also showed that it inhibited the release of pro-inflammatory cytokines (IL-1α, IL-6 and IL-8); and suppressed the phosphorylation cascade of JNK and p38 MAPK to reduce the expression level of active-caspase3, ultimately prevented cell apoptosis. Thus, the EPS produced by L. rhamnosus VHPriobi O17 have the potential to be used for human anti-UVB irradiation.

Hypocholesterolemic, antidiabetic and bioactive properties of ultrasound-stimulated exopolysaccharide produced by Lactiplantibacillus plantarum strains

This study aimed to investigate the effects of ultrasound (US) pretreatment (100 W, 30 kHz; 0%, 25%, 50%, and 75% amplitudes, 15 min) on exopolysaccharide (EPS) production efficiency of L. plantarum LS5 and LU5 strains. Physicochemical (molecular weight and sugar composition) and bioactive properties of extracted EPSs such as antibiofilm, α-amylase inhibition, cholesterol-lowering, and antioxidant activities were investigated. The EPS production yield of strains was growth-associated and LS5 had more efficiency than LU5 but their molecular weights did not differ, significantly (p > 0.05). The predicted results were mathematically confirmed experimental data. The α and β values (EPS production constant) were obtained by the Elovich model (EM) using a genetic algorithm indicated that the highest EPS production was found for LS5 and an amplitude of 50%. Extracted EPSs were heteropolysaccharides and showed dose-dependent antioxidant properties. DPPH scavenging activity of LS5-EPS was higher than LU5-EPS but their Fe3+ reducing power did not differ markedly (p > 0.05). They had the highest and lowest antibiofilm activity against S.aureus and E. coli, respectively. The maximum α-amylase inhibition (35.13%) and Cholesterol-lowering activities (42.56%) were achieved by LU5-EPS and LS5-EPS, respectively. As a result, LS5-EPS was more bioactive than LU5-EPS, and ultrasound pretreatment at 50% amplitude is an efficient way for increasing LS5-EPS production, which has a great potential in the production of functional food and employment in pharmaceutical industries.

Micrococcus yunnanensis and Psychrobacter sp. as Potential Producers of Polymers from Hot Spring

Polyhydroxyalkanoates (PHAs) and exopolysaccharides (EPSs) are biopolymers bacteria under nutrient-limiting conditions. In this study, bacterial strains were isolated from hot springs. Soil samples were collected from Tatta Pani, Azad Kashmir, Pakistan. Bacterial strains AJ2 and AJ3 were selected due to their ability to produce PHAs and EPSs. Phylogenetic analysis showed that strain AJ2 was Micrococcus yunnanensis and AJ3 was Psychrobacter sp. Three carbon sources (glucose, glycerol, and molasses) were used for polymer production. The effect of high pH (8) and high temperature (55 °C) was checked on PHAs and EPSs production. The highest yield of PHAs was given by strain AJ3 (89.43%) with molasses. When grown at 55 °C for 24 hours, strain AJ3 showed the highest PHAs accumulation, 79% with glucose. At alkaline pH 8, strain AJ3 gave 34% PHAs with molasses. The highest EPSs production was observed for strain AJ3. AJ3 gave 70g/L of EPSs with both glucose and glycerol. The amplification of the phaC gene was done to confirm the genetic basis of PHAs production. FTIR analysis showed clear bands at 1722 cm-1 and 2925 cm-1 representing the carbonyl and alkyl groups of PHAs, respectively.

Exopolysaccharyde production by Cryptococcus laurentii SD7 using molasses and corn steep liquor as substrates

Microbial polysaccharides are of great biotechnological and commercial interest and have wide application in the food, cosmetic and medicine industries. Exopolysaccharide (EPS) production by the yeast Cryptococcus laurentii SD7, isolated from fresh water molluscs, was studied using agro-industrial byproducts as substrates in the submerged fermentation. The Central Composite Design (CCD) 23 was used to study the influence of pH, different concentrations on sugarcane molasses and corn steep liquor (CSL), for 48 hours. According to the results, the highest EPS production occurred at the initial pH 5 and at 8.4% concentration of sugarcane molasses, which were statistically significant variable at 10% (p < 0.1). The concentration of CSL had no influence in the studied range, thus, it can be used lowest concentration (0.3%). The time course of EPS production showed that while cell growth peaked within 48 hours, the highest EPS production (6.61 g L-1) occurred at 168 hours, with a productivity of about 0.04 g L-1 h-1. The pH of the medium remained approximately constant throughout the fermentation process. The yeast C. laurentii SD7 showed great potential for EPS production at a low cost and with sustainable substrates.

In vitro assessment of probiotic and virulence potential of Enterococcus faecium strains derived from artisanal goatskin casing Tulum cheeses produced in central Taurus Mountains of Turkey

In the present study, nine Enterococcus (Ent.) faecium isolates were isolated from Tulum cheese produced traditionally in the central Taurus Mountains of Turkey during ripening period and were characterized to investigate their probiotic potential via gastrointestinal resistance, and adhesion ability, functional properties tests, and safety (haemolytic activity, antibiotic resistance, biogenic amine production, and PCR detection of some virulence factors) analyses. All of these strains proved to be resistant to bile salt and simulated gastric juice. All the isolates displayed good safety assessment regarding vancomycin susceptibility except for isolate 1050. Additionally, the majority of isolates showed high exopolysaccharide production while isolate 12 showed a desirable cholesterol removal rate. Also, five of Ent. faecium isolates indicated antibacterial activity against both Listeria monocytogenes ATCC 7644 and Staphylococcus aureus ATCC 25923. Isolates 394 and 894 were examined based on the presence of virulence genes encoding for aggregation substance (asa1), cytolysin (CylLL, CylLs, CylM, CylB, CylA), gelatinase (gelE), and hyaluronidase (hylefm). Isolate 894 harbored three virulence determinants including asa1, gelE and CylA while the virulence cylLL,S,cylM, Hylefm, gelE, and CylA genes were detected in isolate 394. Overall, isolate 894 was shown to be a potential candidate for further in vivo investigations as a probiotic culture.

Production and characterization of biomass and exopolysaccharides obtained in submerged culture under different initial pHs used in the cultivation of Colletotrichum gloeosporioides and Rhizopus stolonifer

Colletotrichum gloeosporioides (GC003) and Rhizopus stolonifer (RS001) were cultivated in two different liquid culture media: LC1 (glucose 40 g L-1, yeast extract 3 g L-1 and tryptone peptone 2 g L-1) and LC2 (glucose 40 g L-1, yeast extract 3 g L-1 and tryptone peptone 10 g L-1) for the production of mycelial biomass and exopolysaccharides (EPS). By using the liquid culture (LC2) under pH of 4.5 presented the highest biomass content (15.73 g L-1) in the propagation of Rhizopus stolonifer. The highest production of exopolysaccharides (1.74 g L-1) was obtained by the liquid culture (LC2) under pH of 4.5 in the cultivation of Colletotrichum gloeosporioides. The results presented that the production of biomass and exopolysaccharides (EPS) is directly related with the pHs values and the strain used in the cultivation.

Effect of Amaranth and Quinoa Flours on Exopolysaccharide Production and Protein Profile of Liquid Sourdough Fermented by Weissella cibaria and Lactobacillus plantarum.

Exopolysaccharides (EPSs) are known for their positive contribute to the technological properties of many foods, including bakery products. These molecules can be obtained performing piloted fermentation with lactic acid bacteria (LAB). In order to select strains able to produce EPS, a screening test in agar medium containing sucrose, fructose or glucose as carbohydrate source was performed on 21 LAB strains. Results allowed to select 8 Weissella cibaria, 2 Weissella confusa, and 2 Leuconostoc spp. strains as EPS producers only in the presence of sucrose. A further screening in liquid medium enriched with sucrose (10%) (mMRS_S) indicated the W. cibaria strain C43-11 as the higher EPS producer. The selected strain was used to develop liquid sourdoughs (LSs) with dough yield (DY) 500, fermented for 15 h and based on wheat flour and wheat gluten or pseudocereals (quinoa or amaranth) in ratio 1:1, in the presence or not of sucrose at 3% (w/w, LS weight), in comparison to Lactobacillus plantarum ITM21B, a strain not producing EPS in mMRS_S. Results indicated that the use of pseudocereals favored the EPS production. Formulations were optimized by modifying DY (500 or 250), sucrose concentration (3 or 6%) and flour ratio. LSs were characterized for the content of organic acids (lactic, acetic, phenyllactic, OH-phenyllactic), pH, TTA, EPS, viscosity, total protein degradation and protein pattern. The highest EPS production (20.79 g/kg) and viscosity (1168 mPa s) were obtained in LS (DY 250, sucrose 6%) based on quinoa flour and started with C43-11 strain. The LS was characterized by the presence of phenyllactic and OH-phenyllactic acids, protein degradation by 51.7% and proteins in the range 14–80 kDa. In these conditions, also strain ITM21B was able to produce EPS at level of 4.61 g/kg and to degrade proteins by 53.8% in LS based on wheat and quinoa flours (1:1) (DY250 and sucrose 3%). Therefore, results demonstrated that the use of selected conditions (flour type, DY, sucrose) can stimulate specific attributes of strains making them suitable for production of short fermented (15 h) LSs which can be used as bread improvers.

Deciphering the Factors for Nodulation and Symbiosis of Mesorhizobium Associated with Cicer arietinum in Northwest India

The compatibility between rhizobia and legumes for nitrogen-fixing nodules and the stages of root hair curling, formation of infection thread, and nodulation initiation have been vitally studied, but the factors for the sustainable root surface colonization and efficient symbiosis within chickpea and rhizobia have been poorly investigated. Hence, we aimed to analyze phenotypic properties and phylogenetic relationships of root-nodule bacteria associated with chickpea (Cicer arietinum) in the north-west Indo Gangetic Plains (NW-IGP) region of Uttar Pradesh, India. In this study, 54 isolates were recovered from five agricultural locations. Strains exhibited high exopolysaccharide production and were capable of survival at 15–42 °C. Assays for phosphate solubilization, catalase, oxidase, Indole acetic acid (IAA) production, and 1-aminocyclopropane-1-carboxylic acid (ACC) deaminase activity revealed that all the tested isolates possessed plant growth-promoting potential. Metabolic profiling using Biolog plates indicated that patterns of substrate utilization differed considerably among isolates. A biofilm formation assay showed that isolates displayed a nearly four-fold range in their capacity for biofilm development. Inoculation experiments indicated that all isolates formed nodules on chickpea, but they exhibited more than a two-fold range in symbiotic efficiency. No nodules were observed on four other legumes (Phaseolus vulgaris, Pisum sativum, Lens culinaris, and Vigna mungo). Concatenated sequences from six loci (gap, edD, glnD, gnD, rpoB, and nodC) supported the assignment of all isolates to the species Mesorhizobium ciceri, with strain M. ciceri Ca181 as their closest relative.

Characterization of Exopolysaccharides Produced by Marine Bacillus Megaterium

Exopolysaccharides (EPSs) are polymers with large molecular weight that consist of various residues of sugar. These are desired because the substitution of synthetic polymers is degradable and non-toxic. Most microorganisms have the ability to synthesize and excrete exo polysaccharides with new chemical compositions, characteristics and structures in order to have important applications in various areas. The current study based on marine bacterial isolates screening the production of exo polysaccharide. Among the four exopolysaccharide producing isolates, the isolate PMSS12 had the highest production of exo polysaccharides. The efficient marine bacterial isolate PMSS12 was further identified by sequence of 16S rRNA. The PMSS12 isolate was confirmed as Bacillus megaterium. Then the exopolysaccharide produced by Bacillus megaterium was characterized by using FTIR, NMR and SEM.