Production and partial characterization of the exopolysaccharide from Pleurotus sajor caju Abstract Purpose Microbial exopolysaccharides (EPSs) are very important because they are used in biotechnological applications in different industrial areas. The aim of the study was to determine the best EPS producer Pleurotus sp., to optimize EPS production and to perform partial purification and characterization of the produced EPS. Methods After the production conditions were optimized, the EPS was isolated and partially purified. EPS was characterized by HP-TLC, 1H-NMR, FT-IR, and TGA. Hydroxyl, superoxide, and DPPH radical scavenging activities of the EPS were also investigated spectrophotometrically. Result The best EPS producer and its incubation period in submerged fermentation were determined as Pleurotus sajor caju and on 5 days, respectively. Culture conditions to increase EPS production were optimized as follows (in per liter): 90 g of glucose, 10 g of yeast extract, 10 g of peptone, and 100 mM of Mg2+. The optimal initial pH, temperature, and an agitation rate of culture were determined as 5.0, 25 °C, and 150 rate min−1, respectively. The highest EPS production was determined as 33.32 ± 1.6 g L−1. After isolation of EPS, one active fraction was obtained by gel filtration chromatography. EPS is composed mainly of glucose according to HP-TLC analysis. Conclusion To the results, EPS had a complex structure by having carbohydrate and protein contents. The produced EPS had high degradation temperature as well as high antioxidant activity.

Methylglyoxal induces glycation and oxidative stress in Saccharomyces cerevisiae Abstract Purpose Hyperglycemia causes abnormal accumulation of methylglyoxal (MGO) and concomitant DNA, protein glycation. These pathophysiological changes further leads to diabetic complications. Yeast Saccharomyces cerevisiae is one of the best model to study MGO-induced glycation modifications. The aim of the present study was to investigate the effect of MGO on protein, DNA glycation, and oxidative stress markers using S. cerevisiae as a system. Methods Saccharomyces cerevisiae cells were incubated with 8 mM of MGO for 4 h and 24 h. After incubation, protein and DNA samples were isolated from the lysed cells. The samples were analyzed for various glycation (fructosamine, β-amyloid, free amino group, free thiol group, and hyperchromic shift analysis) and oxidative stress markers (total antioxidant potential, catalase, glutathione, and lipid peroxidation). Results MGO (8 mM) acted as a potent glycating agent, causing protein and DNA glycation in treated yeast cells. The glycation markers fructosamine and β-amyloid were significantly elevated when incubated for 4 h as compared to 24 h. Oxidative stress in the glycated yeast cells alleviated cellular antioxidant capacity and reduced the cell viability. Conclusion MGO caused significant glycation modifications of proteins and DNA in yeast cells. It also triggered increase in intracellular oxidative stress. MGO-induced protein, DNA glycation, and oxidative stress in S. cerevisiae indicate the suitability of the yeast model to study various biochemical pathways involved in diabetic complications and even conformational pathologies.

First outbreak reported caused by Erysipelothrix species strain 2 in turkeys from poultry-producing farms in Brazil Abstract Purpose The aims of this study were to report the first isolation of Erysipelothrix sp. strain 2 (ES2) associated with clinical signs of diseases as well as mortality in turkeys and identify the antimicrobial resistance of the isolates. Methods We evaluated 118 farms for bacteriological analysis and TaqMan real-time PCR to identify the microorganism in different organs. After this, we made the epidemiological analysis between the positive flocks and the mortality mean. We performed the sequencing of the 16S rRNA region and the assessment of antimicrobial resistance. Results We have identified 18 (15.25%) as ES2-positive flocks, without any other species from the same genus being found. After analysing the organ samples, we found liver as the organ of choice for the isolation of the ES2. The sequencing of 16S rRNA region of ES2 identified high homology with E. tonsillarum and E. rhusiopathiae, suggesting that it is not the best-suited target to identify this species. We have found a positive association between isolation of the bacteria in organs and flocks’ mortality. Positive flocks had a mortality mean rate of 6.87%, which is significantly greater than 3.76% in negative flocks. Ill turkeys had gross lesions of generalized septicaemia. The bacterial isolates showed high resistance to fosfomycin and trimethoprim/sulfamethoxazole and sensibility to norfloxacin, amoxicillin and lincomycin/spectinomycin. Conclusion This is the first study in the world that addressed ES2 as the causative agent of erysipelas in turkey.

The K296-D320 region of recombinant levansucrase BA-SacB can affect the sensitivity of Escherichia coli host to sucrose Abstract Purpose A mutant BA-SacB-Del encoding BA-SacB minus K296-D320 region was constructed to analyze its effect on catalytic characteristics of the enzyme as well as help deepen understanding of the catalytic mechanism of BA-SacB and even proteins of GH68 family. Methods Based on the comparison of levansucrases from Bacillus amyloliquefaciens (BA-SacB) and Sphingopyxis macrogoltabida (SM-Lev), a mutant BA-SacB-Del encoding BA-SacB minus K296-D320 region was constructed and its effect on catalytic characteristics of the enzyme was analyzed. Results Deletion of this region would undoubtedly affect the conserved structure (i.e., central negatively charged cavity surrounded by five antiparallel β-strands) shared by the GH68 family. Therefore, Escherichia coli-expressing mutant BA-SacB-Del could more efficiently catalyze the production of levan in media containing high concentration of sucrose, which is unrealizable for BA-SacB. Conclusions This result should be valuable for understanding this conditional lethal mechanism. Therefore, this study should be very valuable for understanding the catalytic mechanism of BA-SacB and even proteins of the GH68 family. More importantly, levan can be conveniently produced by direct fermentation of sucrose-containing media with E. coli-expressing BA-SacB-Del which is not sensitive to sucrose.

Short-chain fatty acid and vitamin production potentials of Lactobacillus isolated from fermented foods of Khasi Tribes, Meghalaya, India Abstract Purpose Vitamins and SCFA (short-chain fatty acids) production from Lactobacillus isolates are studied due to its health benefits to the human hosts. Lactobacillus strains are widely used in fermented foods, and few of them are reported with vitamin and SCFA production potential. Therefore, in the present study, vitamins and SCFA production capability of isolates were studied to find the potent Lactobacillus cultures for value-added functional food product development. Methods Five Lactobacillus strains, i.e., KGL2, KGL3A, KGL4, RNS4, and WTS4, were isolated from rice-based traditional fermented foods of Garo Hills, Meghalaya, India. All the well grown isolates were morphologically, physiologically, and genetically characterized. Then, vitamins and SCFA were estimated using HPLC based methods. Vitamins produced in vitamins free assay medium and SCFA in milk medium are produced by Lactobacillus. Results Lactic acid bacteria produce essential vitamins like riboflavin, folate, cobalamin, and SCFA which have health impacts (anti-obesity, anti-diabetics, anti-microbial, and other chronic diseases prevention) to the host. These vitamins are essential for cellular and metabolic growth of living system. In the study, five potent Lactobacillus isolates viz., KGL2 (Lactobacillus fermentum), KGL3A (Lactobacillus plantarum), KGL4 (Lactobacillus fermentum), RNS4 (Lactobacillus rhamnosus), and WTS4 (Lactobacillus fermentum) were considered for vitamins (B2, B12, and B9) and SCFA productions (lactate, butyrate, and acetate). However, KGL3A had shown highest B2 production (0.7 μg/ml) while KGL2 exhibited maximum B12 production (0.05 μg/ml) after 36 h. Moreover, WTS4 attributed highest folate production (0.09 μg/ml) after 24 h. In addition, RNS4 reported the maximum short-chain fatty acid production (0.77 g/l acetic acid, 0.26 g/l lactic acid, and 0.008 g/l butyric acid respectively). Conclusions Potent Lactobacillus isolates from traditional fermented foods of Garo Hills, Meghalaya, India (North East Part of India) showed maximum production of B2, B9, and B12 as well as short-chain fatty acids and could be used for their application as health beneficial functional fermented dairy products.

Numerical analysis of phenotypic properties, genomic fingerprinting, and multilocus sequence analysis of Bradyrhizobium strains isolated from root nodules of Lembotropis nigricans of the tribe Genisteae Abstract Purpose The aim of this study was to estimate the level of genomic and phenotypic diversity as well as the genus and species position of bacterial strains isolated from root nodules of Lembotropis nigricans (family Fabaceae). Methods The genomic diversity of studied L. nigricans nodule symbionts was examined by using BOX-PCR and AFLP (amplified fragment length polymorphism) fingerprinting techniques. To assign bacteria to the genus, numerical analysis of phenotypic features and comparative analysis of 16S rDNA sequences were performed. The comparative analysis of combined atpD, dnaK, gyrB, and rpoB gene sequences (multilocus sequence analysis, MLSA) was used to determine the most closely related species to the studied bacteria. Results Both BOX-PCR and AFLP techniques revealed a high level of genomic heterogeneity of L. nigricans nodulators. Among 33 studied bacteria, 32 genotypes were delineated by the AFLP method and 27 genotypes were identified by the BOX-PCR fingerprinting. The numerical analysis of 86 phenotypic characteristics of L. nigricans nodule isolates and reference rhizobia showed that studied bacteria belong to the genus Bradyrhizobium. Affiliation of L. nigricans nodule isolates to the genus Bradyrhizobium was supported by comparative analysis of 16S rDNA sequences and the concatenation of atpD, dnaK, gyrB, and rpoB gene sequences. MLSA indicated also that L. nigricans microsymbionts are members of Bradyrhizobium japonicum. Conclusion L. nigricans root nodule symbionts are members of Bradyrhizobium japonicum and exhibit high phenotypic and genomic diversity important for their survival in soil.

Microbial lipids from cellulolytic oleaginous fungus Penicillium citrinum PKB20 as a potential feedstock for biodiesel production Abstract Purpose Microbial lipids derived from oleaginous fungi are considered as an alternative feedstock for biodiesel production. We attempt to isolate a cellulolytic oleaginous fungi as a potential feedstock for biodiesel production. Methods The fungus was identified by 5.8 S-ITS rRNA gene sequencing. The extracellular enzyme activities were recorded after every 24 h for 7 days. Nile red staining and fluorescence microscopy was used to visualise the lipid bodies within the fungal hyphae. A renewable heterogeneous base catalyst derived from Musa balbisiana cola peels was used for the transesterification of Penicillium citrinum PKB20 derived oil into biodiesel. GC-MS analysis was used to analyse the fatty acid methyl esters (FAME) profile of the transesterified lipids. Results Penicillium citrinum PKB20 was isolated from detritus rich soil of Assam, India. The endoglucanase, xylanase and β-glucosidase enzyme activities were found to be 292.83 ± 0.29, 111.72 ± 0.45 and 6.54 ± 0.13 U/mg respectively. The specific enzyme activity for extracellular lipase was found to be 3.12 ± 0.16 U/mg. It could accumulate up to 60.61% of lipids in nitrogen-limited medium (7.34 ± 0.45 g/L biomass production). The extracted lipids were converted to biodiesel with 89.3% conversion efficiency. The predominant fatty acids were oleic acid (30.09%), palmitic acid (20.25%) and linoleic acid (33.14%) suggesting a balance between oxidative stability and cold flow properties for suitable biodiesel quality. Conclusion Penicillium citrinum PKB20 was found to be a potential feedstock for biodiesel production with desirable fuel properties. The cellulolytic nature could be utilised for simultaneous lipid production directly on cellulosic substrates.

Assessment of biotechnological potentials of strains isolated from repasso olive pomace in Tunisia Abstract Purpose The agri-food industry generates significant amounts of byproducts, among them repasso olive pomace (ROP) which are rejected and can constitute a serious environmental problem. Our study aimed to investigate the diversity of microbiota isolated from ROP and screen for their biotechnological potentials. Methods A collection of 102 strains (88 bacteria and 14 fungi) was obtained from a ROP sample. The diversity of the bacterial collection was evaluated by amplification of the internal transcribed spacers between the 16S and the 23S rRNA genes (ITS-PCR) and by 16S rRNA sequencing. Fungal identification was performed by polymerase chain reaction (PCR) amplification of the ITS1–5.8S–ITS2 ribosomal DNA region. The specific enzymatic screening of the detected microorganisms was tested. Result Partial 16S rRNA gene sequencing performed on 44 isolates showed a high level of identity with known strains. Fungal strains identification showed that they belong to four families: Trichocomaceae, Pleurostomataceae, Mucoraceae, and Bionectriaceae. Our results demonstrated that Gram-positive bacteria were mostly active, particularly for protease, lipase, amylase, cellulase laccase, and for biosurfactant production. From the 88 isolated bacteria, Firmicutes were the most prevalent and microdiverse. Bacillus and Paenibacillus, together with some other Gram-negative bacteria such as Pseudocitrobacter anthropi, and Acinetobacter johnsonii showed significant hydrolytic activities and biosurfactant production. The 14 isolated fungi showed a high capacity of enzyme production. This is the first study in Tunisia describing the microbial diversity in ROP as well as the isolation of Bacillus mojavensis producing lipase. Conclusion Microorganisms especially fungi present in the repasso olive cake produce diverse hydrolytic enzymes of industrial interest.

Acetobacter sacchari sp. nov., for a plant growth-promoting acetic acid bacterium isolated in Vietnam Abstract Purpose Two bacterial strains, designated as isolates VTH-Ai14T and VTH-Ai15, that have plant growth-promoting ability were isolated during the study on acetic acid bacteria diversity in Vietnam. The phylogenetic analysis based on 16S rRNA gene sequences showed that the two isolates were located closely to Acetobacter nitrogenifigens RG1T but formed an independent cluster. Methods The phylogenetic analysis based on 16S rRNA gene and three housekeeping genes’ (dnaK, groEL, and rpoB) sequences were analyzed. The genomic DNA of the two isolates, VTH-Ai14T and VTH-Ai15, Acetobacter nitrogenifigens RG1T, the closest phylogenetic species, and Acetobacter aceti NBRC 14818T were hybridized and calculated the %similarity. Then, phenotypic and chemotaxonomic characteristics were determined for species’ description using the conventional method. Results The 16S rRNA gene and concatenated of the three housekeeping genes phylogenetic analysis suggests that the two isolates were constituted in a species separated from Acetobacter nitrogenifigens, Acetobacter aceti, and Acetobacter sicerae. The two isolates VTH-Ai14T and VTH-Ai15 showed 99.65% and 98.65% similarity of 16S rRNA gene when compared with Acetobacter nitrogenifigens and Acetobacter aceti and they were so different from Acetobacter nitrogenifigens RG1T with 56.99 ± 3.6 and 68.15 ± 1.8% in DNA-DNA hybridization, when isolates VTH-Ai14T and VTH-Ai15 were respectively labeled. Moreover, the two isolates were phenotypically distinguished from Acetobacter nitrogenifigens in growth in the presence of 0.35% acetic acid (v/v), on nitrogen-free LGI medium and D-mannitol, and in no ability to solubilize phosphate. Conclusion Therefore, the two isolates, VTH-Ai14T(= VTCC 910031T= BCC 67843T= TBRC 11175T= NRIC 0977T) and VTH-Ai15 (= VTCC 910032 = BCC 67844 = TBRC 11176 = NRIC 0978), can be assigned to an independent species within the genus Acetobacter, and the name of Acetobacter sacchari sp. nov. is proposed for the two isolates.

Selection of potentially probiotic Kluyveromyces lactis for the fermentation of cheese whey–based beverage Abstract Purpose This work aimed to assess the probiotic potential of different Kluyveromyces lactis strains isolated from Canastra cheese and to produce a fermented cheese whey beverage added to beetroot juice using the selected strain. Methods Kluyveromyces lactis strains were tested for their resistance to the passage through the simulated gastrointestinal tract, adhesion properties, and functional effects such as inhibition of enteric pathogens, short-chain fatty acids (SCFA) production, and β-galactosidase activity. The selected strain was used to produce a fermented cheese whey beverage added to beetroot juice in different proportions. The produced beverages were characterized using HPLC for sugars, Folin-Ciocalteu for total phenolic content, DPPH for antioxidant activity, and GC-MS for volatiles compounds. Results Except B51, all strains showed viability above 75% after exposure to the simulated gastric and duodenal juices. The aggregation rates were above 84% in 24 h. Only B9 and C16 strains presented hydrophobicity above 60%. The highest B9 β-galactosidase activities were 2.17 U/g and 2.21 U/g for pH 7 and 9, respectively. The B9 SCFA profile was similar to that found for Saccharomyces bourllardi. The fermented cheese whey beverages presented phenolic content ranging from 102.75 to 291.61 μg EAG/mL and inhibition of DPPH ranging from 38.69 to 81.02% after 21 days of storage, besides being lactose free. Esters and acetates were the most abundant compounds. Conclusions Kluyveromyces lactis B9 presented interesting results as a potential probiotic yeast. The produced beverages allowed the delivery of K. lactis B9 through innovative product with functional properties.