Optimization of propionic acid production in apple pomace extract with Propionibacterium freudenreichii

Abstract

Sequential optimization of propionate production using apple pomace was studied. All experiments were performed in a static flask in anaerobic conditions. Effect of apple pomace as nitrogen source against conventional N sources (yeast extract, peptone) was studied. The double increase was observed in propionic acid production while using yeast extract and peptone (0.29?±?0.01?g/g), as against the use of only apple pomace extract (APE) (0.14?±?0.01?g/g). Intensification of propionic acid fermentation was also achieved by increasing the pH control frequency of the culture medium from 24-(0.29?±?0.01?g/g) to 12-hour intervals (30?°C) (0.30?±?0.02?g/g) and by increasing the temperature of the culture from 30 to 37?°C (12-hour intervals of pH control) (0.32?±?0.01?g/g). An important factor in improving the parameters of fermentation was the addition of biotin to the medium. The 0.2?mg/L dose of biotin allowed to attain 7.66?g/L propionate with a yield of 0.38?±?0.03?g/g (12-hour intervals of pH control, 37?°C).     

Cost-effective and concurrent production of industrially valuable xylano-pectinolytic enzymes by a bacterial isolate Bacillus pumilus AJK

Simultaneous production of xylanase and pectinase by Bacillus pumilus AJK under submerged fermentation was investigated in this study. Under optimized conditions, it produced 315?±?16 IU/mL acidic xylanase, 290?±?20 IU/mL alkaline xylanase, and 88?±?9 IU/mL pectinase. The production of xylano-pectinolytic enzymes was the highest after inoculating media (containing 2% each of wheat bran and Citrus limetta peel, 0.5% peptone, 10?mM MgSO₄, pH 7.0) with 2% of 21-hr-old culture and incubated at 37°C for 60?hr at 200?rpm. Xylanase retained 100% activity from pH 6.0 to10.0 after 3?hr of incubation, while pectinase showed 100% stability from pH 6.0 to 9.0 even after 6?hr of incubation. Cost-effective and concurrent production of xylanase and pectinase by a bacterial isolate in the same production media suggests its potential for various biotechnological applications. This is the first report of simultaneous production of industrially important extracellular xylano-pectinolytic enzymes by B. pumilus.     

Development and Evaluation of a Novel Delivery System Containing Phytophospholipid Complex for Skin Aging

Citrus auranticum and Glycyrrhiza glabra are rich in anti-oxidant polyphenols helpful in prevention of skin aging. Polyphenols have high polarity and lower skin penetration resulting in lower cutaneous delivery. The present work is attempted to develop a novel polyherbal phospholipid complex cream to improve cutaneous delivery of polyphenols for sustained anti-oxidant action. Phytochemical and in vitro anti-oxidant evaluation was done on methanolic extracts of orange peel and liquorice powder. Total phenolic content, total flavonoid content, and anti-oxidant assays were done on different ratios of orange peel and liquorice extract. Ratio 1:2 gave highest total phenolic content (TPC) (530.00?±?1.56 mg gallic acid equivalent (GAE)?g^?1 extract), total flavonoid content (TFC) (246.25?±?1.03 mg rutin equivalent (RUE)?g^?1 extract), 2,2-diphenyl-1-picrylhydrazyl (DPPH) scavenging activity (87.99?±?0.64%), and H₂O₂ scavenging activity (72.47?±?0.86%) and hence was used for formulation. Solvent evaporation method using methanol with 1:1 extract to phospholipid ratio was found to have entrapment efficiency of 93.22?±?0.26%. Evaluation parameters like scanning electron microscopy (SEM), Fourier transform infrared spectrophotometry (FT-IR), and differential scanning calorimetry (DSC) confirmed formation of complex. The complex was formulated as oil-in-water cream and evaluated for various parameters. The optimized cream containing 1% complex was non-irritant and was found to be stable for 3-month period under conditions of stability study. Ex vivo diffusion studies showed that extract phospholipid complex cream had better retention of polyphenols in the skin when compared to conventional extract cream giving prolonged and stronger topical action. The cream had an anti-elastase activity of 28.02?±?0.95% at concentration of 3000 μg ml^?1 (w/v). Thus, the developed safe and stable polyherbal phytophospholipid complex cream exhibited good potential as anti-aging cosmeceutical.     

Use of response surface methodology to optimize protease synthesis by a novel strain of Bacillus sp. isolated from Portuguese sheep wool

Aims: To investigate the influence of yeast extract, peptone, temperature and pH upon protease productivity by Bacillus sp. HTS102 – a novel wild strain isolated from wool of a Portuguese sheep breed (Merino). Methods and Results: A 2⁴ full factorial, central composite design together with response surface methodology was used to carry out the experiments and analyse the results, respectively. Among the individual parameters tested, temperature and peptone concentration produced significant effects upon protease productivity. A high correlation coefficient (R² = 0·994, P < 0·01) indicated that the empiric second‐order polynomial model postulated was adequate to predict said productivity, with the optimum loci characterized by: temperature of 43°C, peptone content of 1·4 g l^?1, pH of 5·1 and yeast extract concentration of 10·0 g l^?1. Conclusions: Protease synthesis depends chiefly on temperature and peptone level. The maximum protease activity was more than twice that obtained with the basal medium, so the experimental design and analysis undertaken were effective towards process optimization. Significance and Impact of the Study: Rational choice of processing conditions for maximum protease productivity will be relevant if an economically feasible fermentation process based on Bacillus sp. HTS102 is intended.     

EFFECT OF VITAMIN E SUPPLEMENTATION AND PARTIAL SUBSTITUTION OF POLY- WITH MONO-UNSATURATED FATTY ACIDS IN PIG DIETS ON MUSCLE,AND MICROSOME EXTRACT a-TOCOPHEROL CONCENTRATION AND LIPID OXIDATION

The experiment was organized in a 3×2 factorial arrangement with three dietary fat blends and a basal (20 mg kg^?1 diet) or supplemented (220 mg kg^?1) level of α-tocopheryl acetate. Dietary vitamin E and monounsaturated to polyunsaturated fatty acid ratio (dietary MUFA/PUFA) affected muscle α-tocopherol concentration (α-tocopherol [log μg g^?1]=0.18 (±0.105)+0.0034 (±0.0003)·dietary α-tocopherol [mg kg^?1 diet] (P<0.0001)+0.39 (±0.122)·dietary MUFA/PUFA (P<0.0036)). An interaction between dietary α-tocopherol and dietary MUFA/PUFA exists for microsome α-tocopherol concentration (α-tocopherol [log μg g^?1]=1.14 (±0.169) (P<0.0001)+0.0056 (±0.00099)·dietary α-tocopherol [mg kg^?1 diet] (P<0.0001)+0.54 (±0.206)·dietary MUFA/PUFA (P<0.0131)?0.0033 (±0.0011)·dietary α-tocopherol [mg kg^?1)]×dietary MUFA/PUFA (P<0.0067)), and hexanal concentration in meat (hexanal [ng·g^?1]=14807.9 (±1489.8)?28.8 (±10.6) dietary α-tocopherol [mg·kg^?1] (P<0.01)?8436.6 (±1701.6)·dietary MUFA/PUFA (P<0.001)+24.0 (±11.22)·dietary α-tocopherol·dietary MUFA/PUFA (P<0.0416)). It is concluded that partial substitution of dietary PUFA with MUFA lead to an increase in the concentration of α-tocopherol in muscle and microsome extracts. An interaction between dietary α-tocopherol and fatty acids exists, in which at low level of dietary vitamin E inclusion, a low MUFA/PUFA ratio leads to a reduction in the concentration of α-tocopherol in microsome extracts and a concentration of hexanal in meat above the expected values.     

Cyanophycin production from feather hydrolysate using biotechnological methods

Abstract

Cyanophycin is a bacterial storage polymer for carbon, nitrogen and energy with emerging industrial applications. As efficient cyanophycin production is enhanced by peptone, but commercial peptones are very expensive, thereby increasing the overall production cost, an enzymatically produced feather hydrolysate (FH) is assessed as a cheap replacement of peptone to lower the costs and make cyanophycin production more economically feasible. Keratinase production using feather as the sole carbon/nitrogen source by S.pactum 40530 at 30-L fermentation scale was achieved within 93?h with degradation rate of 96.5%. A concentration of 60?g/L of FH, generated by keratinolytic activity (8?×?10³?U?g^?1L^?1d^?1) within 24?h, was used as the main carbon/peptone source to produce cyanophycin. The growth performances of E. coli DapE/L using FH was compared to that of casamino acids (CA) and up to 7.1?±?0.4 and 5.3?±?0.3?g/L of cell mass were obtained after 72?h from FH and CA, respectively. Cyanophycin production yielded 1.4?±?0.1g/L for FH with average molecular mass of 28.8 and 1.4?±?0.2 for CA with average molecular mass of 35.3, after 60?h. For the first time, FH generated by biotechnological methods from environmentally problematic, abundant and renewable feather bioresource was successfully used for cyanophycin biopolymer production.     

Five-factor-at-a-time (FFAT) approach for optimal production of an extracellular RNase from Bacillus safensis RB-5

Abstract

A Gram-positive, rod-shaped, endospore-forming, and RNA-degrading bacterium RB-5 was isolated from a soil sample. Based on 16-rDNA gene sequence, the bacterium RB-5 was identified as Bacillus safensis (Accession number KX443714.1). The bacterium appeared to be related to Bacillus safensis KL-052, an other-member of genus Bacillus. One-factor-at-a-time (OFAT) and Response Surface Methodology (RSM) statistical approaches were used to optimize the fermentation broth to obtain an improved extracellular RNase production from B. safensis RB-5. These approaches improved RNase activity of B. safensis KL-052 from 4.26 to 7.85?U/mL. The OFAT approach was used to study the effects of supplementation of carbon, nitrogen and physical conditions, which included temperature, pH and agitation rate on extracellular RNase production by B. safensis KL-052. Five variables screened by Central Composite Design (CCD) were employed to evaluate their interactive effects on RNase production by the organism. CCD selected 2⁵ factorial values obtained by the statistical approach were peptone 1.13% (w/v), sodium nitrate 1.13% (w/v), MgSO₄ 0.06% (w/v), pH 8.5, and temperature 35?°C for RNase production by B. safensis. The highest predicted value of RNase was 7.05?U/ml while actual obtained value was 7.85?U/ml that was ～84% and 1.84-fold higher than OFAT approach.     

Enhancement of carotenoids and lipids production by oleaginous red yeast Sporidiobolus pararoseus KM281507

Bioconversion of biodiesel-derived crude glycerol into carotenoids and lipids was investigated by a microbial conversion of an oleaginous red yeast Sporidiobolus pararoseus KM281507. The methanol content in crude glycerol (0.5%, w/v) did not show a significant effect on biomass production by strain KM281507. However, demethanolized crude glycerol significantly supported the production of biomass (8.64?±?0.13?g/L), lipids (2.92?±?0.03?g/L), β-carotene (15.76?±?0.85?mg/L), and total carotenoids (33.67?±?1.28?mg/L). The optimal conditions suggested by central composite design were crude glycerol concentration (55.04?g/L), initial pH of medium (pH 5.63) and cultivation temperature (24.01°C). Under these conditions, the production of biomass, lipids, β-carotene, and total carotenoids were elevated up to 8.83?±?0.05, 4.00?±?0.06?g/L, 27.41?±?0.20, and 53.70?±?0.48?mg/L, respectively. Moreover, an addition of olive oil (0.5???2.0%) dramatically increased the production of biomass (14.47?±?0.15?g/L), lipids (6.40?±?0.09?g/L), β-carotene (54.43?±?0.95?mg/L), and total carotenoids (70.92?±?0.51?mg/L). The oleic acid content in lipids was also increased to 75.1% (w/w) of total fatty acids, indicating a good potential to be an alternative biodiesel feedstock. Meanwhile, the β-carotene content in total carotenoids was increased to 76.7% (w/w). Hence, strain KM281507 could be a good potential source of renewable biodiesel feedstock and natural carotenoids.     

Methane emissions from an alpine fen in central Switzerland

Methane emissions and below ground methane pore water concentrations were determined in an alpine fen at 1,915?m a.s.l. in central Switzerland. The fen represented an acidic (pH 4.5–4.9), nutrient-poor to mesotrophic habitat dominated by Carex limosa, Carex rostrata, Trichophorum caespitosum and Sphagnum species. From late fall to late spring the fen was snow-covered. Throughout winter the temperatures never dropped below 0°C at 5?cm below the vegetation surface. Methane emissions in June, July, August and September were in the range of 125 (±26)–313 (±71)?mg?CH₄?m^?2?day^?1 with a tendency to decrease along the summer season. Mean methane pore water concentrations at a depth of 20–40?cm below the vegetation surface were 526 (±32)?μM in June and in the range of 144 (±10)–233 (±7)?μM in July, August and September. At a depth of 0–20?cm the mean methane pore water concentrations dropped back to <20?μM with an almost linear decrease between 0 and 15?cm. Oxygen pore water concentrations were close to air saturation in the first few centimeters and dropped back below detection limit at a depth of 20?cm. In July and August the pore water concentrations of dissolved organic carbon (DOC) were in the range of 7.2–10.1?mg?C?l^?1 at all depths. The pore water concentrations of acetate, formate and oxalate were in the range of 2.0–8.2?μM at all depths. Methanotrophic and methanogenic communities were quantified using pmoA and mcrA, respectively, as marker genes. The abundances of both communities showed a distinct peak at a depth of 10–15?cm below the vegetation surface.     

Life table of Gaeolaelaps aculeifer (Acari: Laelapidae) feeding on larvae of Lycoriella auripila (Diptera: Sciaridae) with stage-specific estimates of consumption

Gaeolaelaps aculeifer (Canestrini, 1883) is a soil-dwelling predatory mite with potential for use as a biological control agent of fungus gnats (Diptera: Sciaridae) in mushroom production. The life table, predation rate and population growth rate of G. aculeifer on a diet of larvae of the sciarid fly, Lycoriella auripila, at 23?±?1°C, 60?±?5% RH and a photoperiod of 0:24 (L:D)?h was investigated. The results revealed that the duration of egg, larva, protonymph, deutonymph, females and males of G. aculeifer were 3.8?±?0.1, 1.4?±?0.1, 3.9?±?0.1, 4.1?±?0.1, 67.7?±?2.8 and 60.3?±?3.1 days, respectively. Net reproductive rate (R₀) was 54.8?±?7.1 offspring, intrinsic rate of increase (r) was 0.12?±?0.01 offspring day^?1, finite rate of increase (λ) was 1.13?±?0.01 day^?1and mean generation time (T) was 32.3?±?0.6 days. The predator consumed a mean of 0.08?±?0.05, 1.73?±?0.18, 3.16?±?0.28 and 75.9?±?7.1 third instar L. auripila larvae during the larval (1.3?±?0.1 days), protonymph (3.9?±?0.1 days), deutonymph (4.1?±?0.1 days) and adult (52.6?±?2.2 days) stages. Population parameters and consumption rates suggest that G. aculeifer has good potential as a biological control agent of L. auripila in mushroom production.     

Evaluation of Arthrospira platensis extracellular polymeric substances production in photoautotrophic, heterotrophic and mixotrophic conditions

The kinetic study of Arthrospira platensis extracellular polymeric substances (EPS) production under different trophic modes??photoautotrophy (100???mol photons m^?2?s^?1), heterotrophy (1.5?g/L glucose), and mixotrophy (100???mol photons m^?2?s^?1 and 1.5?g/L glucose)??was investigated. Under photoautotrophic and heterotrophic conditions, the maximum EPS production 219.61?±?4.73 and 30.30?±?1.97?mg/L, respectively, occurred during the stationary phase. Under a mixotrophic condition, the maximum EPS production (290.50?±?2.21?mg/L) was observed during the early stationary phase. The highest specific EPS productivity (433.62?mg/g per day) was obtained under a photoautotrophic culture. The lowest specific EPS productivity (38.33?mg/g per day) was observed for the heterotrophic culture. The effects of glucose concentration, light intensity, and their interaction in mixotrophic culture on A. platensis EPS production were evaluated by means of 32 factorial design and response surface methodology. This design was carried out with a glucose concentration of 0.5, 1.5, and 2.5?g/L and at light levels of 50, 100, and 150???mol photons m^?2?s^?1. Statistical analysis of the model demonstrated that EPS concentration and EPS yield were mainly influenced by glucose concentration and that conditions optimizing EPS concentration were dissimilar from those optimizing EPS yield. The highest maximum predicted EPS concentration (369.3?mg/L) was found at 150???mol photons m^?2?s^?1 light intensity and 2.4?g/L glucose concentration, while the highest maximum predicted EPS yield (364.3?mg/g) was recorded at 115???mol photons m^?2?s^?1 light intensity and 1.8?g/L glucose concentration.     

Dry anaerobic digestion of high solids content dairy manure at high organic loading rates in psychrophilic sequence batch reactor

Cow manure with bedding is renewable organic biomass available around the year on dairy farms. Developing efficient and cost-effective psychrophilic dry anaerobic digestion (PDAD) processes could contribute to solving farm-related environmental, energy, and manure management problems in cold-climate regions. This study was to increase the organic loading rate (OLR), fed to a novel psychrophilic (20 °C) dry anaerobic digestion of 27 % total solid dairy manure (cow feces and wheat straw) in sequence batch reactor (PDAD-SBR), by 133 to 160 %. The PDAD-SBR process operated at treatment cycle length of 21 days and OLR of 7.0 and 8.0 g total chemical oxygen demand (TCOD)?kg^?1 inoculum day^?1 (5.2?±?0.1 and 5.8?±?0.0 g volatile solids (VS)?kg^?1 inoculum day^?1) for four successive cycles (84 days) produced average specific methane yields (SMYs) of 147.1?±?17.2 and 143.2?±?11.7 normalized liters (NL)?CH₄?kg^?1 VS fed, respectively. PDAD of cow feces and wheat straw is possible with VS-based inoculum-to-substrate ratio of 1.45 at OLR of 8.0 g TCOD kg^?1 inoculum day^?1. Hydrolysis was the limiting step reaction. The VS removal averaged around 57.4?±?0.5 and 60.5?±?5.7 % at OLR 7.0 and 8.0 g TCOD kg^?1 inoculum day^?1, respectively.     

Evaluation of a granular formulation containing Metarhizium brunneum F52 (Hypocreales: Clavicipitaceae) microsclerotia in controlling eggs of Aedes aegypti (Diptera: Culicidae)

We evaluated the potential of a granular formulation of Metarhizium brunneum F52 containing microsclerotia (MbMSc granules) for control of Aedes aegypti by targeting eggs. MbMSc granules produced infective conidia within 14 days after application to 2.5?g moist potting soil, producing 5.9?×?10⁵, 2.08?×?10⁶ and 6.85?×?10⁶ conidia from 1, 5 and 25?mg MbMSc granules, respectively. Application of MbMSc triggered premature eclosion of eggs (EC_50?=?12?mg) with percentages as high as 31?±?2.9% and 67?±?4.3% of the eggs treated with 5 and 25?mg MbMSc granules, respectively, after 14 days on moist filter paper. Premature eclosion of eggs started at 3 days subsequent to MbMSc granule application and survival of larvae was significantly reduced for granule treated eggs (74?±?2.2%, 39?±?2.0% and 23?±?4.9% larvae survived for 1, 5 and 25?mg granule treatments, respectively, EC₅₀?=?4.9?mg). When MbMSc granules were applied in moist potting soil with mosquito eggs, rates of 1, 5 and 25?mg of MbMSc granules significantly reduced adult emergence with only 81?±?2.1%, 47?±?1.9%, and 34?±?2.1% emergence, respectively (EC₅₀?=?7?mg). Eggs treated with increasing concentrations of fungal conidia enhanced premature eclosion of eggs with an EC₅₀?=?1.6?×?10⁶ conidia/mL. Our results demonstrate that MbMSc granules are a promising candidate for control of A. aegypti and that fermentative production of Mb F52 microsclerotia as the active propagule has the potential for use for mosquito control.     

Candida zeylanoides as a new yeast model for lipid metabolism studies: effect of nitrogen sources on fatty acid accumulation

Lipid homeostasis is well-known in oleaginous yeasts, but there are few non-oleaginous yeast models apart from Saccharomyces cerevisiae. We are proposing the non-oleaginous yeast Candida zeylanoides QU 33 as model. The aim of this study was to investigate the influence of the carbon/nitrogen ratio and the type of nitrogen source upon oil accumulation by this yeast grown on shake flask cultures. The maximum biomass was obtained in yeast extract (2.39?±?0.19 g/l), followed by peptone (2.24?±?0.05 g/l), while the highest content of microbial oil (0.35?±?0.01 g/l) and the maximum lipid yield (15.63 %) were achieved with peptone. Oleic acid was the predominant cellular fatty acid in all culture media (>32.23 %), followed by linoleic (>15.79 %) and palmitic acids (>13.47 %). The highest lipid yield using glucose and peptone was obtained at the C/N ratio of 200:1.     

In vitro mature embryo culture protocol of einkorn (Triticum monococcum ssp. monococcum) and bread (Triticum aestivum L.) wheat under boron stress

Mature embryos of einkorn (Triticum monococcum ssp. monococcum) and bread (Triticum aestivum L.) wheat were used for callus induction on media containing four different doses (0, 1, 2 and 4 mg L^?1) of 2,4-D and dicamba supplemented with five different boron concentrations (0, 6.2, 12.4, 24.8, and 37.2 mg L^?1). The obtained callus was transferred to culture media with three (0, 0.5, and 2 mg L^?1) different BAP doses with five boron concentrations for further regeneration. The maximum callus weight in einkorn wheat was in culture media with 1 mg L^?1 dicamba and 6.2 mg L^?1 (3.71?±?0.13 g). Bread wheat had the maximum callus weight on culture media with 4 mg L^?1 dicamba and 12.4 mg L^?1 (3.46?±?0.40 g). The highest plantlet numbers were in only 2 mg L^?1 BAP (2.92?±?0.88) for einkorn wheat and 0.5 mg L^?1 BAP supplemented with 6.2 mg L^?1 boron (3.71?±?1.12) for bread wheat. This indirect regeneration protocol using mature embryos of einkorn and bread wheat under boron stresses expected to be useful for future wheat breeding studies.

     

Production of laccase and manganese peroxidase by Pleurotus pulmonarius in solid-state cultures and application in dye decolorization

The production of ligninolytic enzymes (laccase and Mn-dependent peroxidase) by the white-rot fungus Pleurotus pulmonarius (FR.) Quélet was studied in solid-state cultures using agricultural and food wastes as substrate. The highest activities of laccase were found in wheat bran (2,860?±?250 U/L), pineapple peel (2,450?±?230 U/L), and orange bagasse (2,100?±?270 U/L) cultures, all of them at an initial moisture level of 85 %. The highest activities of Mn peroxidase were obtained in pineapple peel cultures (2,200?±?205 U/L) at an initial moisture level of 75 %. In general, the condition of high initial moisture level (80–90 %) was the best condition for laccase activity, while the best condition for Mn peroxidase activity was cultivation at low initial moisture (50–70 %). Cultures containing high Mn peroxidase activities were more efficient in the decolorization of the industrial dyes remazol brilliant blue R (RBBR), Congo red, methylene blue, and ethyl violet than those containing high laccase activity. Also, crude enzymatic extracts with high Mn peroxidase activity were more efficient in the in vitro decolorization of methylene blue, ethyl violet, and Congo red. The dye RBBR was efficiently decolorized by both crude extracts, rich in Mn peroxidase activity or rich in laccase activity.     

Evaluating different carriers of Metarhizium brunneum F52 microsclerotia for control of adult Asian longhorned beetles (Coleoptera: Cerambycidae)

Microsclerotia (MS) of Metarhizium brunneum strain F52 (Hypocreales: Clavicipitaceae) were processed as granules using three carriers: kaolin clay, microcrystalline cellulose (MCC), or diatomaceous earth (DE). In a series of experiments aimed at comparing viable conidial production, each MS carrier type was hydrated using a decreasing range of water activities on glycerol or polyethylene glycol (PEG200)-amended media. Conidial density and percent germination of conidia declined significantly as water activity was lowered. All three carrier types produced >2–6?×?10⁹ viable conidia/gram at higher water activities (а_w >0.987) but were still capable of producing 2.9?×?10⁷?±?1.6?×?10⁶ conidia/g (30% glycerol а_w?=?0.883) and 1.9?×?10⁷?±?6.5?×?10⁶ conidia/g (30% PEG200 а_w?=?0.924) at the lowest tested water activities. MS carrier types were sprayed onto 0.4?m length logs with or without hydromulch formulation. The median survival times of Asian longhorned beetles, Anoplophora glabripennis (Coleoptera: Cerambycidae), exposed by climbing double the length of the logs of hydromulch-treated bark, were 16.5–20.5?d while beetles exposed to logs without hydromulch formulation had median survival times of 22–25.5?d. Overall, experiments showed that there were few biologically significant differences between the MS carrier types.     

Optimization of critical medium components using response surface methodology for biomass and extracellular polysaccharide production by <Emphasis Type="Italic">Agaricus blazei</Emphasis>

Response surface methodology (RSM) was applied to optimize the critical medium ingredients of Agaricus blazei. A three-level Box–Behnken factorial design was employed to determine the maximum biomass and extracellular polysaccharide (EPS) yields at optimum levels for glucose, yeast extract (YE), and peptone. A mathematical model was then developed to show the effect of each medium composition and its interactions on the production of mycelial biomass and EPS. The model predicted the maximum biomass yield of 10.86 g/l that appeared at glucose, YE, peptone of 26.3, 6.84, and 6.62 g/l, respectively, while a maximum EPS yield of 348.4 mg/l appeared at glucose, YE, peptone of 28.4, 4.96, 5.60 g/l, respectively. These predicted values were also verified by validation experiments. The excellent correlation between predicted and measured values of each model justifies the validity of both the response models. The results of bioreactor fermentation also show that the optimized culture medium enhanced both biomass (13.91 ± 0.71 g/l) and EPS (363 ± 4.1 mg/l) production by Agaricus blazei in a large-scale fermentation process.     

Isolation,screening, and optimization of bacterial strains for novel transglutaminase production

Transglutaminases are a class of transferases known to form isopeptide bond between glutamine and lysine residues in a protein molecule. Increasing demand for transglutaminase in food and other industries and its low productivity have compelled researchers to isolate and screen micro-organisms with potential to produce it. In the present investigation around 200 isolates were screened for extracellular secretion of microbial transglutaminase (MTGase). Isolate B4 showed enzyme activity of 1.71?±?0.2?U/mL followed by isolate C2 which showed 1.61?±?0.17?U/mL activity, comparable with the activity of industrially used microbial strains. Biochemical analysis along with 16S r-RNA sequencing revealed these isolates (B4 and C2) to be Bacillus nakamurai and a variant of Bacillus subtilis, respectively. Amongst the various production media screened, a medium containing starch and peptone was found best for MTGase production. Correlation between growth, enzyme production, and sugar utilization was also studied and maximum enzyme production was obtained after 48 to 60?hr. Highest MTGase titer (3.95?±?0.03?U/mL for B4 and 2.65?±?0.17?U/mL for C2) was obtained by optimization of parameters. The enzyme was characterized for temperature and pH optima, pH and thermal stability, and effect of metal ions, suggesting its potential use in future applications.