Peptone Concentration Research Articles

A new cost-effective, selective and differential medium for the isolation of Cronobacter spp.

The objective of the present study was to develop a new selective, differential and cost-effective medium (Kim and Rhee — KR-medium) for the isolation of Cronobacter spp. In this new medium, which contained salicin as a differential agent, Cronobacter spp. generated typical colonies with characteristic violet-colored centers surrounded by a transparent to opalescent border, and the growth of other microorganisms (40 strains) was inhibited or produced visually distinguishable colonies. Using healthy and heat- and desiccation-injured cells, the quantity of nutrients was adjusted to determine the optimal recovery rate, selectivity, differentiation and cost-effectiveness. Peptone and salicin concentrations were established as 10 and 8 g/L, respectively. The KR medium was then validated using salicin fermenting organisms, including Cronobacter spp. (52 strains), Enterobacter cloacae (50 strains) and Klebsiella pneumonia (10 strains) isolated from clinical and food specimens. All strains of Cronobacter spp. produced typical colonies and other salicin fermenting organisms were easily distinguishable from Cronobacter spp. with the exception of 2 E. cloacae strains. The verification of KR medium was carried out in powdered infant formula artificially inoculated with healthy, heat-injured, and desiccation-injured Cronobacter spp. and the expected typical colonies were appeared. The KR medium had a high specificity (98%) and sensitivity (100%), with no false-negative results. Moreover, we show that the cost of the KR medium is much lower than that of other selective and differential media. The use of the KR medium for the selective isolation of Cronobacter spp. in laboratories and food industry settings may therefore lessen the financial burden of Cronobacter spp. detection.

Formulation of Culture Medium with Agroindustrial Waste for β-Galactosidase Production from Kluyveromyces marxianus ATCC 16045

Seven strains of the genus Kluyveromyces were screened for β-galactosidase activity and Kluyveromyces marxianus ATCC 16045 was selected as the best enzyme producer for culture medium optimization. The production of β-galactosidase by submerged cultivation was evaluated using a factorial design and response surface methodology. The culture medium containing whey and parboiled rice effluent was formulated to maximize the production of β-galactosidase. The effects of the initial pH and the concentrations of whey lactose, peptone, (NH4)2SO4, yeast extract, and parboiled rice effluent on enzyme production were studied using a 2 IV 6-2 fractional design. A CCRD (24 trials plus axial and central points) was used for the four variables selected from the fractional design (lactose, peptone, (NH4)2SO4 and yeast extract), with β-galactosidase activity as the response. The optimum conditions established for production were a whey (lactose) concentration of 120 g/L, a yeast extract concentration of 5 g/L, a peptone concentration of 15 g/L, a (NH4)2SO4 concentration of 15 g/L, a parboiled rice effluent concentration of 30 g/L, and a pH value of 4.0. Under these conditions, the highest enzymatic activity of 10.4 U/mL was measured, being 9.5–9.7 as the values predicted by the proposed model, showing an enzymatic activity increase of 30% using alternative sources of lactose and nitrogen for β-galactosidase production.

Anaerobic H 2 production at elevated temperature (60 °C) by enriched mixed consortia from mesophilic sources

Two different enriched mixed consortia from mesophilic sources were used for H 2 production from glucose at 60 °C. The variables were initial pH, nitrogen source, iron and sulfate. pH had a crucial effect and iron was slightly positive for the biohydrogen production performance of the mixed culture. On the other hand, H 2 production decreased with the increasing of ammonia, peptone and sulfate concentrations. Metabolic pathways of mixed culture were affected in different ways depending on the differences in microbial community. The PCR–DGGE and sequencing based microbial community analysis revealed that two enriched mixed cultures had different microbial diversity and both culture were dominated mainly by Thermoanaerobacterium species.

AKTIVITAS LIPOLITIK Rhizopus microsporus var. rhizopodiformis ISOLAT UICC No. 6

The lipolytic activity of Rhizopus microsporus var rhizopodiformis isolat UICC No. 6. A study was carried out to examine the effect of peptone concentration (2,5% or 5%), inoculum concentration (0,1%, 0,5% or 1%) and incubation period (0 – 96 hours, interval 12 hours) on the lipolytic activity of Rhizopus microsporus var rhizopodiformis isolat UICC No. 6. Fermentation was done using the basal medium from Samad and the lipolytic activity on olive oil substrate was measured employing titration method with 0,05M NaOH. Lipolytic activity is expressed as unit/ml and one unit is defined as 1 􀁭mol fatty acid liberated per minute. Results show that optimum lipolytic activity was obtained from 1 % inoculum, 5% peptone after 72 hours incubation period. Keywords: lipolytic, Rhizopus, inoculum, incubation

Evaluation and optimization of ethanol production from carob pod extract by Zymomonas mobilis using response surface methodology

In this research, ethanol production from carob pod extract (extract) using Zymomonas mobilis with medium optimized by Plackett-Burman (P-B) and response surface methodologies (RSM) was studied. Z. mobilis was recognized as useful for ethanol production from carob pod extract. The effects of initial concentrations of sugar, peptone, and yeast extract as well as agitation rate (rpm), pH, and culture time in nonhydrolyzed carob pod extract were investigated. Significantly affecting variables (P = 0.05) in the model obtained from RSM studies were: weights of bacterial inoculum, initial sugar, peptone, and yeast extract. Acid hydrolysis was useful to complete conversion of sugars to glucose and fructose. Nonhydrolyzed extract showed higher ethanol yield and residual sugar compared with hydrolyzed extract. Ethanol produced (g g(-1) initial sugar, as the response) was not significantly different (P = 0.05) when Z. mobilis performance was compared in hydrolyzed and nonhydrolyzed extract. The maximum ethanol of 0.34 ± 0.02 g g(-1) initial sugar was obtained at 30°C, initial pH 5.2, and 80 rpm, using concentrations (g per 50 mL culture media) of: inoculum bacterial dry weight, 0.017; initial sugar, 5.78; peptone, 0.43; yeast extract, 0.43; and culture time of 36 h.

Statistical Optimization and Neural Modeling of Amylase Production from Banana Peel Using Bacillus subtilis MTCC 441

Optimization of process parameters is of critical task in developing an industrial fermentation process for various reasons. Many techniques are available for experimental design and optimization of fermentation process parameters, i.e., fermentation medium composition and conditions, each having its own advantages and disadvantages. In this work response surface methodology (RSM) with central composite design (CCD) of experiments and artificial neural network (ANN) coupled with global optimization technique (TOMLAB’s Direct Alogoritm—gblSolve) are used for optimization of process parameters for the production of alpha amylase using banana peel as the substrate and bacterial source Bacillus subtilis MTCC 441. A 46 run central composite design was used to plan the experiment with six parameters (banana peel concentration, peptone concentration, pH, temperature, incubation time and inoculum size) with five levels. The maximum amylase activity predicted by CCD and ANN is in good agreement with the experimental values at the optimized levels. The present work shows the better optimization and prediction capacity of ANN techniques compared to RSM technique.

Differential Filamentation of Candida albicans and Candida dubliniensis Is Governed by Nutrient Regulation of UME6 Expression

Candida dubliniensis is closely related to Candida albicans; however, it is responsible for fewer infections in humans and is less virulent in animal models of infection. C. dubliniensis forms fewer hyphae in vivo, and this may contribute to its reduced virulence. In this study we show that, unlike C. albicans, C. dubliniensis fails to form hyphae in yeast extract-peptone-dextrose (YPD) medium supplemented with 10% (vol/vol) fetal calf serum (YPDS medium). However, C. dubliniensis filaments in water plus 10% (vol/vol) fetal calf serum (WS), and this filamentation is inhibited by the addition of peptone and glucose. Repression of filamentation in YPDS medium could be partly overcome by preculture in synthetic Lee's medium. Unlike C. albicans, inoculation of C. dubliniensis in YPDS medium did not result in increased UME6 transcription. However, >100-fold induction of UME6 was observed when C. dubliniensis was inoculated in nutrient-poor WS medium. The addition of increasing concentrations of peptone to WS medium had a dose-dependent effect on reducing UME6 expression. Transcript profiling of C. dubliniensis hyphae in WS medium identified a starvation response involving expression of genes in the glyoxylate cycle and fatty acid oxidation. In addition, a core, shared transcriptional response with C. albicans could be identified, including expression of virulence-associated genes including SAP456, SAP7, HWP1, and SOD5. Preculture in nutrient-limiting medium enhanced adherence of C. dubliniensis, epithelial invasion, and survival following coculture with murine macrophages. In conclusion, C. albicans, unlike C. dubliniensis, appears to form hyphae in liquid medium regardless of nutrient availability, which may account for its increased capacity to cause disease in humans.

Statistical Optimization of Pullulanase Production by Raoultella planticola DSMZ 4617 Using Sago Starch as Carbon and Peptone as Nitrogen Sources

Response surface methodology based on central composite design was employed for statistical optimization of medium components for the production of pullulanase by Raoultella planticola DSMZ 4617. The combined effects of three independent variables, i.e., concentrations of sago starch and peptone and initial culture pH were analyzed using a reduced cubic model, which was developed by central composite design in predicting the optimum yield of pullulanase activity. Under these conditions, the model predicted a maximum production of pullulanase (1.94 U/mL) at 6.12 g/L sago starch, 15.34 g/L peptone, and at initial culture pH of 7.23. By applying the statistical design, the pullulanase production was enhanced to about nearly two times higher (1.70 U/mL) as compared with the fermentation using nonoptimized medium (0.95 U/mL). It was observed that the experimental values obtained were in good agreement with the values predicted from the models with relatively small errors between the values.

Xylose fermentation to biofuels (hydrogen and ethanol) by extreme thermophilic (70 °C) mixed culture

Combined biohydrogen and bioethanol (CHE) production from xylose was achieved by an extreme thermophilic (70 °C) mixed culture. Effect of initial pH, xylose, peptone, FeSO 4, NaHCO 3, yeast extract, trace mineral salts, vitamins, and phosphate buffer concentrations on bioethanol and biohydrogen yield was investigated in batch experiments. Results obtained showed that initial pH, concentration of xylose, peptone, and FeSO 4 significantly affected biohydrogen and bioethanol production, while the concentration of NaHCO 3 was only significant for bioethanol production. By changing cultivation conditions the culture could be directed to mainly produce ethanol with maximum ethanol yield of 1.60 mol ethanol/mol-xylose corresponding to 95.8% of the theoretical ethanol yield based on degradation of xylose through ethanologenic pathway, or mainly hydrogen with maximum hydrogen yield of 1.84 mol H 2/mol-xylose corresponding to 55% of the theoretical hydrogen yield based on acetate metabolic pathway. An empirical model was established to reveal the quantitative effect of factors significant for biohydrogen (quadratic model) production and for bioethanol (linear model) production. Changes in hydrogen/ethanol yields observed were due to the shift of the metabolic pathway between ethanol or hydrogen production, rather than changes in bacterial community composition at genus level. Thermoanaerobacter related bacteria were found to be the dominant hydrogen/ethanol producers.

Production of a highly glucose tolerant β-glucosidase by Paecilomyces variotii MG3: optimization of fermentation conditions using Plackett–Burman and Box–Behnken experimental designs

β-Glucosidases (β-d-glucoside glucohydrolase, 3.2.1.21) are a group of enzymes mainly involved in the hydrolysis of β-glycosidic bonds connecting carbohydrate residues in different classes of β-d glycosides. During cellulose degradation they convert cellobiose and cellooligosaccharides produced by the endo and exoglucanases to glucose. Most of the microbial β-glucosidases are inhibited by glucose. This limits their application in commercial scale cellulose degradation ventures. Solid state fermentation production of a highly glucose tolerant β-glucosidase by a novel isolate of Paecilomyces was optimized using a two step statistical experiment design. In the first step which employed a Plackett–Burman design, the effects of parameters such as moisture, temperature, pH, inoculum concentration, incubation time and different concentrations of (NH4)2SO4, KH2PO4, NaCl, peptone and cellobiose were evaluated. The parameters with significant influence on the process were selected and fine tuned in the second step using a Box–Behnken design. The model obtained was validated and a peptone concentration of 2 g/l, inoculum concentration of 1.2 × 106 spores/ml and an incubation period of 96 h were found to be optimum for the maximum production of the enzyme. The optimization resulted in a doubling of the enzyme production by the fungus.

Detection of Staphylococcus Aureus in Different Liquid Mediums Using Wireless Magnetoelastic Sensor

Abstract The magnetoelastic Staphylococcus aureus (S. aureus) wireless sensor was fabricated to detect S. aureus in different liquid mediums. Approximately 0.2 mL bacterial solution with proper concentration was taken into testing cuvette containing 2 mL of liquid medium, and the magnetoelastic sensor resonance frequency changed with the growth of bacteria. By changing the concentration of beef extract and peptone, sensor had the most frequency response in culture medium (CM) 2-2 incubated with 2 × 105 cells mL−1 S. aureus. The results indicated that the sensor can be used to determine S. aureus in the concentrations range of 3 × 103–2 × 107 cells mL−1 in CM and 104–107 cells mL−1 in milk, with a detection limit of 103 and 104 cells mL−1, respectively. The sensor frequency shift was correlated to the logarithmic value of the concentration of S. aureus. The coefficient was 0.98 in milk and 0.99 in CM.

Optimization of probiotic and lactic acid production by Lactobacillus plantarum in submerged bioreactor systems

Biomass and lactic acid production by a Lactobacillus plantarum strain isolated from Serrano cheese, a microorganism traditionally used in foods and recognized as a potent probiotic, was optimized. Optimization procedures were carried out in submerged batch bioreactors using cheese whey as the main carbon source. Sequential experimental Plackett-Burman designs followed by central composite design (CCD) were used to assess the influence of temperature, pH, stirring, aeration rate, and concentrations of lactose, peptone, and yeast extract on biomass and lactic acid production. Results showed that temperature, pH, aeration rate, lactose, and peptone were the most influential variables for biomass formation. Under optimized conditions, the CCD for temperature and aeration rate showed that the model predicted maximal biomass production of 14.30 g l(-1) (dw) of L. plantarum. At the central point of the CCD, a biomass of 10.2 g l(-1) (dw), with conversion rates of 0.10 g of cell g(-1) lactose and 1.08 g lactic acid g(-1) lactose (w/w), was obtained. These results provide useful information about the optimal cultivation conditions for growing L. plantarum in batch bioreactors in order to boost biomass to be used as industrial probiotic and to obtain high yields of conversion of lactose to lactic acid.

Optimization of α‐amylase production in solid substrate fermentation

AbstractResponse surface methodology (RSM) was used to optimize the medium components of α‐amylase production using solid substrate fermentation (SSF). Hazelnut cake (HC), peptone, yeast extract (YE), and (NH4)2SO4 were selected as independent variables for optimization. Central composite design (CCD) was used in design experiments and analysis results. This procedure limited the number of actual experiments performed while allowing possible interactions between the independent variables. By using CCD, 30 experiments were performed for determining the interaction of independent variables and optimization of fermentation medium. The P‐value of the coefficient of linear effect of (NH4)2SO4 concentrations, which was obtained as 0.0001 has shown that this parameter has the greatest effect on the production of α‐amylase. Model F‐value (5.62) implies that the model is significant. The highest α‐amylase activity (4895 IU) was measured when the HC, peptone, YE, and (NH4)2SO4 concentrations in the medium were 22.62, 5.20, 1.62, and 6.81 g L−1, respectively.

Control of the release of digestive enzymes in the caeca of the cricket Gryllus bimaculatus

Abstract In Gryllus bimaculatus, more digestive enzymes (amylase, trypsin, aminopeptidase) are secreted in the caecum of fed crickets than in unfed crickets, but the enzymes are released continuously at a basal rate in unfed animals. The rate of synthesis of the enzymes appears to parallel their rate of release. Digestive enzymes are released in response to a specific ratio of nutrients, although a high nutrient component in the food does not necessarily induce a high digestive enzyme release for that component. Rinsed flat‐sheet preparations of the caecum are incubated with specific nutrients (carbohydrates and proteins) and various concentrations of a neuropeptide (type‐A allatostatin), which affects generally the basal rates of secretion. Both maltose and glucose increase the release of amylase in vitro, but starch produces an inhibition of amylase release at lower concentrations. Bovine serum albumin (BSA), peptone and a mixture of amino acids have almost no effect on the release of aminopeptidase or carboxypeptidase, and only low concentrations of peptone increase trypsin release. High concentrations of both BSA and peptone strongly inhibit trypsin activity, perhaps by excess substrate binding to the trypsin active site. The allatostatin Grybi‐AST 5 elevates the release of amylase in vitro, but not of trypsin or aminopeptidase, in 2‐day‐old fed females. In the caeca from 1‐day‐old unfed crickets, both amylase and the trypsin release are stimulated in the presence of AST 5. The paracrine AST 5 is probably released from the gut endocrine cells and binds to the enzyme‐producing caecal cells.

Production and partial characterization of lipases from a newly isolatedPenicilliumsp. using experimental design

The objective of this work was to investigate the lipase production by a newly isolated Penicillium sp., using experimental design technique, in submerged fermentation using a medium based on peptone, yeast extract, NaCl and olive oil, as well as to characterize the crude enzymatic extracts obtained. Lipase activity values of 9.5 U ml(-1) in 96 h of fermentation was obtained at the maximized operational conditions of peptone, yeast extract, NaCl and olive oil concentrations (g l(-1)) of 20.0, 5.0, 5.0 and of 10.0 respectively. The partial characterization of crude enzymatic extract obtained by submerged fermentation showed optimum activity at pH range from 4.9 to 5.5 and temperature from 37 degrees C to 42 degrees C. The crude extract maintained its initial activity at freezing temperatures up to 100 days. A newly isolated strain of Penicillium sp. used in this work yielded good lipase activities compared to the literature. The growing interest in lipase production is related to the potential biotechnological applications that these enzymes present. New lipase producers are relevant to finding enzymes with different catalytic properties of commercial interest could be obtained, without using genetically modified organisms (GMO).

Production and optimization of a commercially viable alkaline protease from a haloalkaliphilic bacterium

Twenty five haloalkaliphilic bacterial strains were isolated from sea water along the Coastal Gujarat (India) and screened for their ability to secret alkaline proteases. Among them, a potent strain S-20-9 (GenBank accession number EU118360), resembling to Halophilic Bacterium MBIC3303 on the basis of 16S rRNA gene sequencing, was selected for the optimization of enzyme production. S-20-9 produced protease optimally, under aerobic conditions during mid-stationary phase over a broad range of salt (5∼25%, w/v) and pH (7∼10). The optimum production was at pH 9 and 15% (w/v) NaCl. The production was suppressed by lactose, maltose, sucrose, and inorganic nitrogen sources, especially ammonium ions. Further, the production was significantly stimulated by KH2PO4 and suppressed by glucose. Similarly, the production was also suppressed at higher concentrations of gelatin, yeast extract, peptone, and casamino acids, indicating towards a threshold value for nitrogen requirement. The growth and protease production were enhanced by mono-valent cation (KCl), while the divalent cations acted as inhibitors. The study holds significance as only few reports are available on the alkaline proteases from haloalkaliphilic bacteria, particularly those from moderate saline habitats.

Optimizing Media of Lactobacillus rhamnosus for Lactic Acid Fermentation

The aim of this study was to optimize the main media components that affect the production of lactic acid by Lactobacillus rhamnosus fermentation. In the experiment,the two variables (glucose and peptone) were optimized using tbe Central Composite Design (CCD) metbod by STATISTICA Software.The optimization studies were successfully carried out in shake flask experiments. The results indicated that the optimun concentration of glucose and peptone for optimun bacterial grovvth rate and lactic acid production in shake flask were 9.80 and 9.98 g L -1, respectively. The optimwn productivity of the lactic acid was 0.630 g g-l h which correspond to optimwn grovvth rate of the bacteria at 0.341 h-1.

The Different Bio-Effects of Functionalized Multi-Walled Carbon Nanotubes on tetrahymena pyriformis

To promote the applications of namomaterials, the potential toxicity of multi-walled carbon nanotubes (MWCNTs) and their derivates to environment have been studied. With γ-ray irradiation, MWCNTs were modified chemically with glucosamine and decylamine to obtain glucosamine-MWCNTs (g-MWCNTs) and decylamine-MWCNTs (d-MWCNTs). Their toxicological experiments were carried out with Tetrahymena pyriformis. The results illustrate that d-MWCNTs show a dose-dependent growth inhibition to the cells, due to the increasing concentration of toxic decylamine. This was attributed to the biological function performed by the decylamine after it was carried into the cell interior by the tubes. The results have a certain reference value for the applications of MWCNTs used as drug delivery system. Both glucosamine and purified MWCNTs (p-MWCNTs) alone show little biological activity, but g-MWCNTs exhibit a dose-dependent growth stimulation. This is due to the fact that the increasing hydrophilicity of g-MWCNTs promotes the conjugation of nanotubes with soluble peptone in culture medium via noncovalent binding. Uptake of the g-MWCNTs-peptone conjugates with various concentration of peptone by the cells is responsible for the dose-dependent growth stimulation. Consequently we propose the effects of concentration of functional groups, hydrophilicity of functionalized nanotubes as well as sequential nonspecific interaction between nanotubes with some components in culture medium on living system should be taken into account in the study of cytotoxicity of carbon nanotubes. Keywords: Carbon nanotubes, chemical modification, bio-effects, tetrahymena pyriformi

Production of Cellulolytic Enzymes by Aspergillus phoenicis in Grape Waste using Response Surface Methodology

The production of cellulolytic enzymes by the fungus Aspergillus phoenicis was investigated. Grape waste from the winemaking industry was chosen as the growth substrate among several agro-industrial byproducts. A 2 x 2 central composite design was performed, utilizing the amount of grape waste and peptone as independent variables. The fungus was cultivated in submerged fermentation at 30 degrees C and 120 rpm for 120 h, and the activities of total cellulases, endoglucanases, and beta-glucosidases were measured. Total cellulases were positively influenced by the linear increase of peptone concentration and decrease at axial concentrations of grape waste and peptone. Maximum activity of endoglucanase was observed by a linear increase of both grape waste and peptone concentrations. Concentrations of grape waste between 5 and 15 g/L had a positive effect on the production of beta-glucosidase; peptone had no significant effects. The optimum production of the three cellulolytic activities was observed at values near the central point. A. phoenicis has the potential for the production of cellulases utilizing grape waste as the growth substrate.

Selection and Optimization of Bacillus atrophaeus Inoculum Medium and its Effect on Spore Yield and Thermal Resistance

Bacillus atrophaeus's spores are used as biological indicators to monitor sterilization processes and as a Bacillus anthracis surrogate in the development and validation of biosafety methods. The regular use of biological indicators to evaluate the efficiency of sterilization processes is a legal requirement for health services. However, its high cost hinders its widespread use. Aiming at developing a cost-effective inoculum medium, soybean molasses and nutrient-supplemented vinasse were evaluated for their effectiveness in solid-state fermentation (SSF). In biomass production, the results demonstrated that all tested compositions favor growth by providing the nutritional demands of the microorganism. Optimum casein peptone and soybean molasses concentration (1.0%, 2.5%, or 4.0%) was determined by a 2((2-0)) factorial experimental design. The results have showed a positive influence of peptone on biomass production. In order to define peptone final concentration (4.0% or 6.0%), a 2(2) factorial experimental design was used. An optimized medium containing 4.0% soybean molasses and 4.0% casein peptone was similar in performance to a synthetic control medium (tryptone soy broth) in dry-heat thermal-resistant spore production by SSF. An experiment performed under optimum SSF conditions resulted in 1.9 x 10(10) CFU g(-1) dry matter with D (160 degrees C) = 5.2 +/- 0.2 min.