Characterization of Salmonella enterica Biofilms and Antibiofilm Effect of Carvacrol and 2-Aminobenzimidazole.

Biofilm-associated foodborne Salmonella infections in poultry have become increasingly challenging for veterinarians, particularly in developing countries, and warrant thorough investigation. We assessed the biofilm-forming tendency of poultry isolates of Salmonella enterica, namely Salmonella Typhimurium (n = 23), Salmonella Infantis (n = 28), and Salmonella Heidelberg (n = 18), in nutrient-rich Rappaport-Vassiliadis Soya (RVS) peptone broth and nutrient-deficient diluted Tryptone Soya Broth (TSB). Seven of the tested isolates exhibited moderate biofilm formation in diluted TSB, whereas two showed such formation in RVS. In addition, the Congo red agar assay revealed curli and cellulose production in seven isolates. Fourteen specific biofilm-associated genes were analyzed identifying sdiA and seqA to be the most prevalent (100%), and glyA the least prevalent (69.5%). The prevalence of the genes bcsA and csgA was significantly lower in moderate and weak biofilm formers, respectively, as compared with nonbiofilm formers in RVS peptone broth. Furthermore, the compounds carvacrol and 2-aminobenzimidazole (2-ABI) effectively inhibited biofilm formation by Salmonella serovars in RVS peptone and TSB media, respectively. Whereas the antibiofilm activity of 2-ABI against Salmonella has not been reported previously, we determined its most effective concentration at 1.5 mM among tested antibiofilm treatments. These findings indicate that Salmonella strains prevalent in poultry farms have the potential to form biofilms, and the tested compounds should be further explored as supportive or alternative antimicrobials.

Modeling and optimization of antibacterial effect of lichen-associated bacteria, Bacillus subtilis KSRLAB3 strain against marine fouling bacteria, Vibrio alginolyticus.

One of the most commonly occurring bacteria, Bacillus subtilis, can produce a wide variety of secondary metabolites. In this study, the antimicrobial effect of B. subtilis KSRLAB3 against Vibrio alginolyticus was optimized using the Plackett-Burman design (PBD) method, response surface methodology (RSM), and genetic algorithm (GA). Initially, the effects of carbon source, nitrogen source, NaCl concentration, pH, temperature, and incubation time on antimicrobial effects were studied. Among the carbon and nitrogen sources investigated, mannose and peptone elicited maximum antimicrobial effect. Using PBD, the most significant variables that influence the antimicrobial effect were identified, including incubation time, peptone concentration, and temperature. The optimum conditions required for attaining maximum antimicrobial effect was identified using the RSM-GA hybrid method, and the optimum condition includes 49.999 h of incubation time, 4.39 g/L of peptone concentration, and 27.629°C of incubation temperature. The confirmatory experiments performed around the optimum condition showed a zone of inhibition of 35 ± 0.52 mm. Methanolic extract also proved the presence of antibacterial lipopeptide surfactin. Therefore, the RSM-GA hybrid method was successfully used in this study to model the antimicrobial effect of B. subtilis KSRLAB3 against V. alginolyticus. The effective inhibition of V. alginolyticus can be investigated further for the development of antifouling coatings.

Modified Drug-Susceptibility Testing and Screening Culture Agar for Colistin-Susceptible Enterobacteriaceae Isolates Harboring a Mobilized Colistin Resistance Gene mcr-9.

Three isolates of the Enterobacter cloacae complex harboring mcr-9, a member of the colistin resistance mcr gene family encoded on plasmids, were susceptible to colistin, with MICs of 0.125 to 0.5 µg/mL in standard broth microdilution (BMD) tests using cation-adjusted Mueller-Hinton broth (CA-MHB) in accordance with European Committee on Antimicrobial Susceptibility Testing guidelines. In contrast, their MICs for colistin were significantly higher (4 to 128 µg/mL) when BMD tests were performed using brain-heart infusion (BHI) medium, Luria-Bertani (LB) broth, tryptic soy broth (TSB), or CA-MHB supplemented with casein, tryptonen or peptone. Colistin significantly induced mcr-9 expression in a dose-dependent manner when these mcr-9-positive isolates were cultured in BHI or CA-MHB supplemented with peptone/casein. Pretreatment of mcr-9-positive isolates and Escherichia coli DH5α harboring mcr-9 with colistin significantly increased their survival rates against LL-37, a human antimicrobial peptide. Electrospray ionization time-of-flight mass spectrometry analysis showed that a lipid A moiety of lipopolysaccharide was partially modified by phosphoethanolamine in E. coli DH5α harboring mcr-9 when treated with colistin. Of 93 clinical isolates of Enterobacteriaceae, only the mcr-9-positive isolates showed MICs to colistin that were at least 32 times higher in BHI than in CA-MHB. These mcr-9-positive isolates grew on a modified BHI agar, MCR9-JU, containing 3 µg/mL colistin. These results suggest that the BMD method using BHI is useful when performed together with the BMD method using CA-MHB to detect mcr-9-positive isolates and that MCR9-JU agar is useful in screening for Enterobacteriaceae isolates harboring mcr-9 and other colistin-resistant isolates.

[Effects of Nutrients on the Growth of Microcystis aeruginosa and Bacteria in the Phycosphere].

The "bacteria-algae" system plays an important role in water ecosystems. The effects of bacteria in phycospheres on the growth of Microcystis aeruginosa under in-situ nutrient stimulation were studied to explore the bacteria-algae interaction during a cyanobacteria bloom. The results showed that LB medium could inhibit the growth of M. aeruginosa, and the algicidal rate was 86.49%. Sodium acetate, glucose, and sodium citrate could promote M. aeruginosa, and the growth rate was more than 50%. The addition of nutrients in M. aeruginosa could have changed the biocoenosis in the phycosphere and increased the species richness by 16S rRNA gene sequencing, and the number of bacteria in the phycosphere increased dramatically in the LB medium and peptone groups. The physiological and biochemical responses showed that algae suffered serious lipid peroxidation, and superoxide dismutase (SOD) and catalase (CAT) activities first increased significantly and subsequently decreased under the oxidative stress of LB medium or peptone. Scanning electron microscopy (SEM) indicated that the surface of algae cells appeared wrinkled, invaded, and atrophied under LB medium stimulation, whereas bacteria in the phycosphere significantly increased. Furthermore, six strains of algicidal bacteria were isolated from the LB medium and peptone groups, and the algicidal rate of Bacillus sp. A1 was 97.55%, which confirmed that the phycosphere of M. aeruginosa included algicidal bacteria. Therefore, appropriate external nutrient stimulation can produce algicidal bacteria in situ to prevent cyanobacterial blooms.

An Evaluation of Different Types of Peptone as Partial Substitutes for Animal-derived Serum in Vero Cell Culture.

Vero cells are one of the most frequently used cell types in virology. They can be used not only as a vehicle for the replication of viruses, but also as a model for investigating viral infectivity, cytopathology and vaccine production. There is increasing awareness of the need to limit the use of animal-derived components in cell culture media for a number of reasons, which include reducing the risk of contamination and decreasing costs related to the downstream processing of commercial products obtained via cell culture. The current study evaluates the use of protein hydrolysates (PHLs), also known as peptones, as partial substitutes for fetal bovine serum (FBS) in Vero cell culture. Eleven plant-based, two yeast-based, and three casein-based peptones were assessed, with different batches evaluated in the study. We tested the effects of three concentration ratios of FBS and peptone on Vero cell proliferation, four days after the initial cell seeding. Some of the tested peptones, when in combination with a minimal 1% level of FBS, supported cell proliferation rates equivalent to those achieved with 10% FBS. Collectively, our findings showed that plant-based peptones could represent promising options for the successful formulation of serum-reduced cell culture media for vaccine production. This is especially relevant in the context of the current COVID-19 pandemic, in view of the urgent need for SARS-CoV-2 virus production for certain types of vaccine. The current study contributes to the Three Rs principle of reduction, as well as addressing animal ethics concerns associated with FBS, by repurposing PHLs for use in cell culture.

Statistical optimization of media components for production of extracellular lipase from edible mushroom Cantharellus cibarius.

Cantharellus cibarius is a wild edible mushrooms and considered as a plethora of compounds with potential biotechnological applications. This study highlighted the utilization of C. cibarius mushroom in the production of extracellular lipase under submerged fermentation, representing the first report on lipase production by this mushroom. Various physicochemical factors were optimized via one-factor-at-a time (OFAT) method. Maximum enzyme production was recorded when the mushroom mycelium was grown at 30 °C on pH 6.0 for 96 h in the medium supplemented with 1% [(v/v)] olive oil. Productivity of enzyme was affected by variation in the nitrogen sources, carbon sources, metal ions and NaCl salt. Glucose and peptone significantly enhanced enzyme production as carbon and nitrogen sources, respectively. Stimulatory and inhibitory effects were found by Ca2+ and Zn2+ ions, respectively. Furthermore, Box-Behnken Design (BBD) of Response Surface Methodology (RSM) was employed to optimize the interactive effects of specific media components like glucose, olive oil and CaCl2. The regression model was significant with a coefficient of determination (R2) value of 0.9483. Statistically optimized design (RSM) resulted approximately two-fold increase (23.5-42.283 UmL-1) of lipase production than classical optimization method (OFAT), confirmed the validation of model. The kinetic parameters for p-nitrophenyl palmitate hydrolysis, Km and Vmax were 5.24 mM and 0.768 mmol/min/mg respectively, established a high affinity for the substrate.

T7-lac promoter vectors spontaneous derepression caused by plant-derived growth media may lead to serious expression problems: a systematic evaluation.

BACKGROUND: The widespread usage of protein expression systems in Escherichia coli (E. coli) is a workhorse of molecular biology research that has practical applications in biotechnology industry, including the production of pharmaceutical drugs. Various factors can strongly affect the successful construction and stable maintenance of clones and the resulting biosynthesis levels. These include an appropriate selection of recombinant hosts, expression systems, regulation of promoters, the repression level at an uninduced state, growth temperature, codon usage, codon context, mRNA secondary structure, translation kinetics, the presence/absence of chaperons and others. However, optimization of the growth medium's composition is often overlooked. We systematically evaluate this factor, which can have a dramatic effect on the expression of recombinant proteins, especially those which are toxic to a recombinant host. RESULTS: Commonly used animal tissue- and plant-based media were evaluated using a series of clones in pET vector, containing expressed Open Reading Frames (ORFs) with a wide spectrum of toxicity to the recombinant E. coli: (i) gfpuv (nontoxic); (ii) tp84_28-which codes for thermophilic endolysin (moderately toxic); and (iii) tthHB27IRM-which codes for thermophilic restriction endonuclease-methyltransferase (REase-MTase)-RM.TthHB27I (very toxic). The use of plant-derived peptones (soy peptone and malt extract) in a culture medium causes the T7-lac expression system to leak. We show that the presence of raffinose and stachyose (galactoside derivatives) in those peptones causes premature and uncontrolled induction of gene expression, which affects the course of the culture, the stability of clones and biosynthesis levels. CONCLUSIONS: The use of plant-derived peptones in a culture medium when using T7-lac hybrid promoter expression systems, such as Tabor-Studier, can lead to uncontrolled production of a recombinant protein. These conclusions also extend to other, lac operator-controlled promoters. In the case of proteins which are toxic to a recombinant host, this can result in mutations or deletions in the expression vector and/or cloned gene, the death of the host or highly decreased expression levels. This phenomenon is caused by the content of certain saccharides in plant peptones, some of which (galactosides) may act as T7-lac promoter inducer by interacting with a Lac repressor. Thus, when attempting to overexpress toxic proteins, it is recommended to either not use plant-derived media or to use them with caution and perform a pilot-scale evaluation of the derepression effect on a case-by-case basis.

Aspergillus oryzae-Fermented Wheat Peptone Enhances the Potential of Proliferation and Hydration of Human Keratinocytes through Activation of p44/42 MAPK.

Identifying materials contributing to skin hydration, essential for normal skin homeostasis, has recently gained increased research interest. In this study, we investigated the potential benefits and mechanisms of action of Aspergillus oryzae-fermented wheat peptone (AFWP) on the proliferation and hydration of human skin keratinocytes, through in vitro experiments using HaCaT cell lines. The findings revealed that compared to unfermented wheat peptone, AFWP exhibited an improved amino acid composition, significantly (p < 0.05) higher DPPH scavenging capability and cell proliferation activity, and reduced lipopolysaccharide-induced NO production in RAW 264.7 cells. Furthermore, we separated AFWP into eleven fractions, each ≤2 kDa; of these, fraction 4 (AFW4) demonstrated the highest efficacy in the cell proliferation assay and was found to be the key component responsible for the cell proliferation potential and antioxidant properties of AFWP. Additionally, AFW4 increased the expression of genes encoding natural moisturizing factors, including filaggrin, transglutaminase-1, and hyaluronic acid synthase 1-3. Furthermore, AFW4 activated p44/42 MAPK, but not JNK and p38 MAPK, whereas PD98059, a p44/42 MAPK inhibitor, attenuated the beneficial effects of AFW4 on the skin, suggesting that the effects of AFW4 are mediated via p44/42 MAPK activation. Finally, in clinical studies, AFW4 treatment resulted in increased skin hydration and reduced trans-epidermal water loss compared with a placebo group. Collectively, these data provide evidence that AFW4 could be used as a potential therapeutic agent to improve skin barrier damage induced by external stresses.

Investigation on mycelial growth requirements of Cantharellus cibarius under laboratory conditions.

The golden chanterelle represents one of the commonly found, edible mushrooms that is highly valued in various cuisines. The present study focused on assessing the requirements of Cantharellus cibarius such as pH, temperature, as well as the carbon and nitrogen sources for mycelial growth. Optimization of the growth parameters was carried out by one-factor-at-a-time method. The optimal pH and temperature were determined to be 6.0 and 22.5 °C, respectively. Among the various carbon sources studied, sucrose at a concentration of 2% gave maximum mycelial growth and proved to be the most suitable one. Amongst the nitrogen sources studied, peptone, ammonium sulphate, and sodium nitrate, gave the maximum mycelial growth at an optimized concentration of 0.5%. In the presence of beef extract and yeast extract, a change in colony pigmentation from yellow to dark grey was observed. Finally, the carbon to nitrogen ratio of 2:0.5 proved to be optimal for mycelial growth. This study is the first report on the optimisation of in vitro growth requirements of C. cibarius.

Influences of organic nitrogen on the removal of inorganic nitrogen from complicated marine aquaculture water by Marichromatium gracile YL28.

The sediment-water interface is not only an important location for substrate conversion in a mariculture system, but also a major source of eutrophication. This study aimed to clarify the characteristics of inorganic nitrogen (ammonia, nitrite and nitrate) removal by Marichromatium gracile YL28 in the presence of both organic nitrogen and inorganic nitrogen. The results showed that, in the presence of peptone or urea, seaweed oligosaccharides (SOS) effectively enhanced the ammonia removal capacity of YL28 (6.42 mmol/L) and decreased the residual rate by 54.04% or 8.17%, respectively. With increasing peptone or urea concentrations, the removal of both ammonia and nitrate was gradually inhibited, and the residual rates of ammonia and nitrate reached 22.56-34.36% and 12.03-15.64% in the peptone system and 20.65-24.03% and 12.20-13.21% in the urea system, respectively. However, in the control group the residual rates of ammonia and nitrate reached 11.97% and 5.12%, respectively. In addition, the concentrations of peptone and urea did not affect nitrite removal, and YL28 displayed better cell growth and nitrogen removal activity in the presence of bait and SOS. Overall, the ability of YL28 to remove inorganic nitrogen was enhanced in the presence of organic nitrogen.

Decolorization of azo and anthraquinone dyes by crude laccase produced by Lentinus crinitus in solid state cultivation.

White-rot basidiomycetes such as Lentinus crinitus produce laccases with potential use in dye biodegradation. However, high productivity and enzymes with specific properties are required in order to make viable laccase production. We aimed to produce laccase from Lentinus crinitus grown in sugarcane bagasse for dye decolorization. Solid state cultivation medium had sugarcane bagasse added with a nutrient solution of 10 g/L glucose, 1 g/L KH2PO4, 0.5 g/L MgSO4, 0.001 g/L FeSO4, 0.01 g/L ZnSO4, and 0.01 g/L MnSO4. The addition of different nitrogen sources (peptone, urea, or peptone plus urea) and different nitrogen concentrations (0, 0.4, 0.6, 0.8, 1.0, and 1.2 g/L) were evaluated. Enzymatic extract was used in the decolorization of azo dyes, reactive blue 220 (RB220) and reactive black 5 (RB5), and anthraquinone dye, Remazol brilliant blue R (RBBR). The greatest laccase activity (4800 U/g dry mass) occurred when the peptone and urea mixture was added to the solid state cultivation medium. When the nitrogen concentration was 1 g/L, the laccase activity increased to 6555 U/g dry mass. The laccase activity peak occurred on the 10th day, and the maximum decolorization within 24 h was observed with enzymatic extracts obtained on different cultivation days, i.e., 6th day for RB220, 10th day for RB5, and 9th day for RBBR. Manganese and lignin peroxidases were not produced when nitrogen was added to the cultivation medium. The crude enzymatic extract was more effective in the decolorization of azo dyes (RB220 and RB5), more than 90% of decolorization, than anthraquinone dye with 77% decolorization.

Effects of medium composition on the growth and lipid production of microplasmodia of Physarum polycephalum.

Physarum polycephalum is a plasmodial slime mold. One of the trophic stages in the life cycle of this organism is a plasmodium. In submerged culture, plasmodia are fragmented into microplasmodia. The latter both lack cell walls and are capable of rapid growth. There has been limited information on the effects of medium composition on the growth and lipid accumulation of microplasmodia. In this study, optimization of medium components by response surface methodology showed that tryptone and yeast extract concentrations had the most significant effects on lipid and biomass production; significant synergistic interactions between glucose and tryptone concentration on these responses were also recorded. The optimal medium was composed of 20 g/L of glucose, 6.59 g/L of tryptone, and 3.0 g/L of yeast extract. This medium yielded 13.86 g/L of dry biomass and 1.97 g/L of lipids. These amounts are threefold higher than those of the American Type Culture Collection (ATCC) medium. In addition, biomass and lipid production reached maximal values between only 4 and 5 days. Fatty acid compositions analysis by gas chromatography-mass spectrometer (GC-MS) revealed that P. polycephalum lipids consisted mainly of oleic acid (40.5%), linoleic acid (10%), and octadecynoic (15.8%). This is the first report on the fatty acid composition of P. polycephalum microplasmodia. These results suggest that the biomass of microplasmodia could be used as a source of material for direct conversion into biodiesel because of the absence of cell walls or it could also be used as a supplemental source of beneficial fatty acids for humans, albeit with some further evaluation needed.

Production of Valuable Compounds and Bioactive Metabolites from By-Products of Fish Discards Using Chemical Processing, Enzymatic Hydrolysis, and Bacterial Fermentation.

The objective of this report was to investigate the isolation and recovery of different biocompounds and bioproducts from wastes (skins and heads) that were obtained from five species discarded by fishing fleets (megrim, hake, boarfish, grenadier, and Atlantic horse mackerel). Based on chemical treatments, enzymatic hydrolysis, and bacterial fermentation, we have isolated and produced gelatinous solutions, oils that are rich in omega-3, fish protein hydrolysates (FPHs) with antioxidant and antihypertensive activities, and peptones. FPHs showed degrees of hydrolysis higher than 13%, with soluble protein concentrations greater than 27 g/L and in vitro digestibilities superior to 90%. Additionally, amino acids compositions were always valuable and bioactivities were, in some cases, remarkable. Peptones that were obtained from FPHs of skin and the heads were demonstrated to be a viable alternative to expensive commercial ones indicated for the production of biomass, lactic acid, and pediocin SA-1 from Pediococcus acidilactici.

Medium composition optimization, structural characterization, and antioxidant activity of exopolysaccharides from the medicinal mushroom Ganoderma lingzhi.

To contribute towards effective exploitation and utilization of natural antioxidants, response surface methodology (RSM) was employed to optimize the medium composition for the production of exopolysaccharides from the medicinal mushroom Ganoderma lingzhi (GLEPS). An optimal medium for GLEPS production was gave through Plackett-Burman design, path of steepest ascent, and Box-Behnken design as follows: glucose (59.62 g/L), yeast extract (10.03 g/L), CaCO3 (0.2 g/L), thiamine (45.13 mg/L), KH2PO4 (1.0 g/L), peptone (1.5 g/L), Tween 80 (10.26 mL/L), ZnSO4 (0.3 g/L), mannitol (1.5 g/L), MgSO4 (0.5 g/L), and aspartate (8.86 g/L). The GLEPS yield obtained was 3.57 ±â€¯0.21 g/L-3.16-fold higher than that produced in basal medium alone. The resulting GLEPS rich in uronic acid, d-mannose, l-rhamnose, and d-glucose, was a heteropolysaccharide with high-molecular weights (475,000 kDa and 21.6 kDa, 87.97%). It was demonstrated that the GLEPS with higher carbohydrate and uronic acid contents exhibited strong in vitro antioxidant activities via radical scavenging, reductive capacity, and chelation of transition metal catalysis. These findings indicated that RSM is an efficient tool to predict the composition of culture medium required for maximizing GLEPS yield, and GLEPS had potent antioxidant activities and could be explored as a novel natural antioxidant in functional food or medicine.

Process optimization, purification and characterization of alkaline stable white laccase from Myrothecium verrucaria ITCC-8447 and its application in delignification of agroresidues.

The white laccase was produced from Myrothecium verrucaria ITCC-8447 under submerged fermentation. The media components were optimized by response surface methodology (CCD-RSM). The nutritional components (glucose and peptone) and physical parameters (pH and temperature) were optimized by response surface methodology for enhanced laccase production by Myrothecium verrucaria ITCC-8447. The enzyme activity under optimum condition exhibited 1.45 fold increases in laccase activity. The white laccase was subjected to ion exchange chromatography with 6 fold purification. The molecular weight of white laccase was ~63-75kDa as estimated by SDS-PAGE followed by the activity staining with ABTS where green bands confirmed the presence of laccase. The enzyme was stable over an alkaline pH range of 7-9 and the temperature range of 30-40°C. The characterization of white laccase was done by CD spectra, UV-visible absorption, FTIR and XRD. The Km and Vmax values of the purified laccase were 2.5mM and1818.2µmol/min/L. The delignification capability of the white laccase was determined by reduction in Kappa number (58.8%) and Klason lignin (64.7%) of wheat straw after 12h of incubation. Further the delignification was confirmed FTIR and XRD.

Monomethylmercury degradation by the human gut microbiota is stimulated by protein amendments.

Monomethylmercury (MMHg) is a potent neurotoxicant that can be bioaccumulated and biomagnified through trophic levels. Human populations whose diets contain MMHg are at risk of MMHg toxicity. The gut microbiota was identified as a potential factor causing variation in MMHg absorption and body burden. However, little is known about the role of gut microbiota on Hg transformations. We conducted a series of in vitro experiments to study the effects of dietary nutrient change on Hg metabolism and the human gut microbiota using anoxic fecal slurry incubations. We used stable Hg isotope tracers to track MMHg production and degradation and characterized the microbiota using high throughput sequencing of the 16S rRNA gene. We show that the magnitude of MMHg degradation is individual dependent and rapidly responds to changes in nutrient amendments, leading to complete degradation of the MMHg present. Although the mechanism involved remains unknown, it does not appear to involve the well-known mer operon. Our data are the first to show a nutrient dependency on the ability of the simulated human gut microbiota to demethylate MMHg. This work provides much-needed insights into individual variations in Hg absorption and potential toxicity.

Effect of cell culture medium additives on color and acidic charge variants of a monoclonal antibody.

This manuscript summarizes the effect of certain cell culture medium additives on antibody drug substance coloration and acidic charge variants. It has been shown previously that B-vitamins and iron in the cell culture medium could significantly impact color intensity. In this manuscript, we detail the effect of several other cell culture components that have been shown to impact coloration. It is shown that if cystine is used instead of cysteine in the cell culture medium, coloration was reduced. Hydrocortisone has been shown to reduce coloration and boost specific productivity. The effect of a peptone/hydrolysate on coloration was investigated in cell culture experiments, which showed its use can lead to reduced coloration. Mechanisms by which these compounds influence coloration will be briefly discussed. Since it has been previously shown that antibody oxidation could potentially lead to coloration, the current effort was focused on screening for specific antioxidant additives to the culture medium to reduce coloration. An in-vitro incubation model was used to screen antioxidant compounds, several of which were found to significantly reduce antibody color, while some led to significantly increased color. Hypotaurine and carboxymethylcysteine, which had the most significant color reducing effect in the incubation study, were further tested in small-scale bioreactor cell culture experiments. These studies demonstrated that these compounds lead to reduced coloration in cell culture without affecting cell growth and titer. Hypotaurine, hydrocortisone, peptone, and cystine were also shown to reduce the acidic charge variant levels, which was previously shown to correlate with color. © 2018 American Institute of Chemical Engineers Biotechnol. Prog., 2018 © 2018 American Institute of Chemical Engineers Biotechnol. Prog., 34:1298-1307, 2018.

Characterization and Antioxidant Activity of an Exopolysaccharide Produced by Rigidoporus microporus (Agaricomycetes).

In this investigation we developed an optimal fermentation medium to produce an exopolysaccharide (EPS) with antioxidant activity from Rigidoporus microporus. Lactose and tryptone were chosen as the optimal carbon and nitrogen sources, respectively, for EPS production, with a 6-day cultivation cycle. After removing proteins through the use of the Sevag method, one EPS fraction was purified from the culture filtrates by gel filtration chromatography on a Sepharose CL-6B column. The preliminary chemical structure of the EPS fraction was determined by Fourier transform infrared spectroscopy, gas chromatography-mass spectrometry, and nuclear magnetic resonance. The results indicated that the main structure of the EPS consisted of ß-glucopyranose and mannopyranose. Furthermore, conformational parameters such as molecular weight (Mw), intrinsic viscosity ([η]), mean-square radii of gyration (Rg), and hydrodynamic radius (Rh) of the EPS were characterized using a size exclusion chromatography-multiangle light scattering-refractive index viscometry method. It showed that the EPS was a kind of water-soluble polysaccharide with a moderate molecular weight (34.1 × 104) and a flexible, linear random coil chain structure. The antioxidant activity tests suggested that the EPS has great potential application as a natural antioxidant material in foods and medicines.

Composition of the Stabilizer and Conditions of Lyophilization for Preserving Infectious Activity of Influenza Virus.

For stabilization of vaccine preparations, they are lyophilized. The composition of the protective medium is an important parameter affecting the quality of the vaccine after drying. In view of the risk of spreading prion diseases, the use of media containing animal proteins is not recommended. In this study, protective media containing no animal proteins and lyophilization regimen were determined. The optimum lyophilization regimen consisted of three stages: freezing at -70°C, main stage at -35°C, and drying at 24°C. Protective medium containing 4% trehalose or protective medium with 10% sucrose and 5% soy peptone ensured highest stability of the lyophilized vaccine preparation in temperature range of 4-24°C. This can help to overcome possible break in the cold chain, which is important during transporting or storage of vaccine preparations.

Influence of medium composition and physical factors on enhanced production of endoglucanase by locally isolated fungal strain in solid state fermentation.

Endoglucanase is one of the most important enzymes of the cellulase group.  Endoglucanase are involved in the catalytic hydrolysis of cellulose and plays a pivotal role in different sectors like pharmaceutical, textile, detergent, and food processing as well as paper and pulp industry. With consumers getting more and more aware of environmental issues, industries find enzymes as a better option over other chemical catalysts. In the current research different thermophilic fungal strains were isolated from the different sources. Qualitative screening was carried out on the basis of cellulose hydrolysis zone. The quantitative screening was carried out employing solid state fermentation.  The fungal culture, showing highest EG potential was selected identified and assigned the code Aspergillus fumigatus BBT2. Different fermentation media were evaluated and M 2 containing wheat bran gave maximum EG production. The maximal enzyme productivity was recorded in 72 hours, 40°C, pH 5, inoculum size 1.5ml, and moisture content (1:1). Glucose (1%) and peptone (1%) were optimized as best carbon and nitrogen sources, respectively.