Optimization of Xanthan Gum Production from Grape Juice Concentrate Using Plackett-Burman Design and Response Surface Methodology

Low grade grape juice concentrate was used as carbon source for xanthan production. Significant factors affecting xanthan concentration, productivity and viscosity were investigated using Plackett-Burman Design. Based on the obtained results, carbon and nitrogen concentrations, inoculum size and agitation rate, were assumed as significant factors. Broth culture viscosity and xanthan concentration were optimized using Response Surface Methodology with four independent variables: carbon source (30, 40, 50 g l-1), ammonium sulfate as nitrogen source (0.5, 1.25, 2 g l-1), agitation (150, 200, 250 rpm) and inoculum size (5, 10, 15% v v-1). Optimum level for each factor was obtained by desirability function approach. The average of xanthan gum production and its viscosity under optimized conditions were recorded as 14.35 g l-1 and 1268 cP, respectively. The average yield of production and productivity of xanthan within 72 h under optimized conditions were 35% and 0.19 g l-1 h-1, respectively. The current study showed the potential of low-grade grape juice concentrate as an economic carbon source for xanthan gum production

Considerable increase in Poly(3-hydroxybutyrate) production via phbC gene overexpression in Ralstonia eutropha PTCC 1615

Introduction: Poly(3-hydroxybutyrate) (PHB) is a well-known biodegradable polymer produced by some microorganisms and can be a suitable alternative for petrochemical plastics. PHB synthase encoded by phbC gene is the main enzyme in PHB biosynthesis pathway in Ralstonia eutropha. The aim of current study was the transformation of R. eutropha PTCC 1615 with its own phbC gene and evaluation of the overexpression effect on PHB accumulation. Methods: DNA fragment including phbC gene and its promoter and terminator regions, was isolated from R. eutropha PTCC 1615, inserted into pET28a(+) vector, and transferred to the competent bacteria using calcium chloride and heat shock method. The effect of the cloned gene expression on PHB production was investigated with absorption of crotonic acid produced through PHB dehydration. Statistical analyses were carried out by SPSS software. Results: PHB content of cells of the engineered strain was 1.4 times more than that of the native bacteria. This significant difference can be an important finding for improvement of biopolymer production. Conclusion: Overexpression of phbC, the critical gene in PHB biosynthesis pathway, in R. eutropha PTCC 1615 had considerable effect on PHB accumulation

Rheological and Stability Evaluation of Emulsions Containing Fenugreek Galactomannan—Xanthan Gum Mixtures: Effect of Microwave and Ultrasound Treatments

The effects of treating two biopolymers (Trigonella foenum—graceum galactomannan and xanthan gum mixtures) with microwaves and ultrasound on the rheological aspects of O/W emulsions were investigated. The data obtained from steady shear flow were fitted with various models and the best were chosen due to the values of R2 and RMSE. The oscillatory shear rheology data demonstrated that the emulsions not treated with microwaves or ultrasound had viscous-like behavior and treated samples demonstrated weak gel behavior. The values obtained for various rheological parameters (especially apparent viscosity, storage modulus and loss modulus) indicated that fenugreek galactomannan had more impact on the rheological aspects of emulsions in comparison with xanthan gum. In addition, the synergistic interaction between two biopolymers, particularly in samples treated with ultrasound, resulted in better rheological aspects which could be affiliated with the strong bonds between the hydrocolloids. By treating the samples with microwaves and ultrasound, the emulsion stability values of the samples (especially those with a high ratio of galactomannan) significantly increased, which might be connected with various parameters, especially viscosity

Detection of Escherichia coli and Enteroccocus faecalis indices in groundwater sources

Microbial analysis of ground water, as the sole supplying water source in many areas, must be evaluated. Because the treatment of water cannot remove all pathogenic bacteria leaked from domestic wastewater, bacterial analysis of Bojnourd groundwater sources was performed. For this reason, membrane filter (MF) technique and Most Probable Number (MPN) method were used to evaluate the microbial quality of the water. Escherichia coli (E. coli) and Enteroccocus faecalis (E. faecalis) were traced as excremental indices. E. coli was detected from three out of six stations and E. faecalis was only isolated from one station. Although molecular techniques are very rapid and exact methods for detection of microbial community and can identify ‘Viable But Not Cultivable’ (VBNC) bacteria, they are unable to make a distinction between living and non-living microorganisms. By means of a standard technique, it is possible to study living and metabolically active microorganisms. Due to the detection of E.coli and E.feacalis in some stations the sanitization of groundwater must be revised to lessen the microbial population in this groundwater

Development of Insulin Resistance through Induction of miRNA-135 in C2C12 Cells

Abstract Objective: Micro-RNAs (miRNAs) are a class of posttranscriptional regulators that play crucial roles in various biological processes. Emerging evidence suggests a direct link between miRNAs and development of several diseases including type 2 diabetes (T2D). In this study, we aimed to investigate the effect of predicted miRNA and target genes on insulin resistance. Materials and Methods: This experimental study was conducted on the C2C12 cell line. Using bioinformatics tools miRNA-135 and two respective target genes-insulin receptor (Insr) and vesicle associated membrane protein 2 (Vamp2)- were selected as potential factors involved in insulin resistance process. Levels of glucose uptake miRNA expression and respective gene targets were determined after cell transfaction by miR-135. Results: It was determined that Insr gene expression was significantly down-regulated in miR-135 transfected C2C12 cell line (P≤0.05). Interestingly; these transfected cells have shown a significant difference in glucose uptake incomparision the positive control cells, while it was similar to the insulin resistant cell line (P≤0.05). In contrast, no significant alteration of Vamp2 gene expression was observed. Conclusion: Our data indicated no change on the Vamp2 expression level after miRNA transfection, while expression level of Insr was reduced and miR-135 expression was contrarily increased leading to poor stimulation of glucose uptake through insulin, and development of insulin resistance phenotype in C2C12 cell line

Unsaturated fatty acid, cis-2-decenoic acid, in combination with disinfectants or antibiotics removes pre-established biofilms formed by food-related bacteria.

Biofilm formation by food-related bacteria and food-related pathogenesis are significant problems in the food industry. Even though much disinfection and mechanical procedure exist for removal of biofilms, they may fail to eliminate pre-established biofilms. cis-2 decenoic acid (CDA), an unsaturated fatty acid messenger produced by Pseudomonas aeruginosa, is reportedly capable of inducing the dispersion of established biofilms by multiple types of microorganisms. However, whether CDA has potential to boost the actions of certain antimicrobials is unknown. Here, the activity of CDA as an inducer of pre-established biofilms dispersal, formed by four main food pathogens; Staphylococcus aureus, Bacillus cereus, Salmonella enterica and E. coli, was measured using both semi-batch and continuous cultures bioassays. To assess the ability of CDA combined biocides treatments to remove pre-established biofilms formed on stainless steel discs, CFU counts were performed for both treated and untreated cultures. Eradication of the biofilms by CDA combined antibiotics was evaluated using crystal violet staining. The effect of CDA combined treatments (antibiotics and disinfectants) on biofilm surface area and bacteria viability was evaluated using fluorescence microscopy, digital image analysis and LIVE/DEAD staining. MICs were also determined to assess the probable inhibitory effects of CDA combined treatments on the growth of tested microorganisms' planktonic cells. Treatment of pre-established biofilms with only 310 nM CDA resulted in at least two-fold increase in the number of planktonic cells in all cultures. While antibiotics or disinfectants alone exerted a trivial effect on CFU counts and percentage of surface area covered by the biofilms, combinational treatments with both 310 nM CDA and antibiotics or disinfectants led to approximate 80% reduction in biofilm biomass. These data suggests that combined treatments with CDA would pave the way toward developing new strategies to control biofilms with widespread applications in industry as well as medicine

Development of Insulin Resistance through Induction of miRNA-135 in C2C12 Cells

Objective: Micro-RNAs (miRNAs) are a class of posttranscriptional regulators that play crucial roles in various biological processes. Emerging evidence suggests a direct link between miRNAs and development of several diseases including type 2 diabetes (T2D). In this study, we aimed to investigate the effect of predicted miRNA and target genes on insulin resistance. Materials and Methods: This experimental study was conducted on the C2C12 cell line. Using bioinformatics tools miRNA-135 and two respective target genes-insulin receptor (Insr) and vesicle associated membrane protein 2 (Vamp2)- were selected as potential factors involved in insulin resistance process. Levels of glucose uptake miRNA expression and respective gene targets were determined after cell transfaction by miR-135. Results: It was determined that Insr gene expression was significantly down-regulated in miR-135 transfected C2C12 cell line (P≤0.05). Interestingly; these transfected cells have shown a significant difference in glucose uptake incomparision the positive control cells, while it was similar to the insulin resistant cell line (P≤0.05). In contrast, no significant alteration of Vamp2 gene expression was observed. Conclusion: Our data indicated no change on the Vamp2 expression level after miRNA transfection, while expression level of Insr was reduced and miR-135 expression was contrarily increased leading to poor stimulation of glucose uptake through insulin, and development of insulin resistance phenotype in C2C12 cell line

Evaluation of the Relationship between the Incubation Time and Carotenoid Production in Rhodotorula Slooffiae and R. Mucilaginosa Isolated from Leather Tanning Wastewater

Objective(s): Carotenoids which are naturally synthesized by fungi such as yeasts can act as an antioxidant which is closely related to their ability to decrease the risk of a variety of degenerative diseases. In recent years, the increase of demand for carotenoids obtained from natural sources has promoted major efforts to improve carotenoid production from biological sources such as pigmented yeasts. The aim of this study was comparing incubation time and carotenoid production in Rhodotorula slooffiae and R. mucilaginosa isolated from leather tanning wastewater.   Materials and Methods: To isolate the carotenoid pigment, cells were suspended in acetone and broken using a homogenizer, followed by centrifugation and separation of supernatant. In order to study the effect of incubation time, samples were held at 30 С in a shaker at 150 rpm for 24, 48, 72, 96, and 120 hr. For analytical evaluation, pigments were measured spectrophotometrically at 450 nm using the extinction coefficient E1%450=2500. Results: The results showed that the content of total carotenoid in R. slooffiae was the highest when samples were incubated for 72 hr. Overall, R. mucilaginosa had more potential to produce carotenoid. The best incubation periods for R. slooffiae and R. mucilaginosa were 72 hr and 48 hr, respectively. Conclusion: It seemed that the maximum rate of total carotenoid was not directly associated with the maximum amount of cell biomass and the type of carotenoid and their relative amount may vary depending on genus of yeast