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Abstract: This study evaluates the microbial metabolism and energy demand in fermentative biohydrogen production using Clostridium tyrobutyricum FYa102 at different hydraulic retention times (HRT) over a period of 1–18h. The hydrogen yield shows a positive correlation with the butyrate yield, the B/A ratio, and the ratio, but a negative correlation with the lactate yield. A decrease in HRT, which is accompanied by an increased biomass growth, tends to decrease the B/A ratio, due presumably to a higher energy demand for microbial growth. The production of lactate at a low HRT, however, may involve an unfavorable change in e− equiv distribution to result in a reduced hydrogen production. Finally, the relatively high hydrogen yields observed in the bioreactor with the peptone addition may be ascribed to the utilization of peptone as an additional energy and/or amino-acid source, thus reducing the glucose demand for biomass growth during the hydrogen production process. [Copyright &y& Elsevier]

Abstract: We investigated the efficacy of a loop-mediated isothermal amplification (LAMP) assay for rapid screening of seafood samples naturally contaminated with Vibrio parahaemolyticus. A total of 171 seafood samples enriched in alkaline peptone water (APW) were assessed by LAMP assay and conventional culture methods, which consist of a combination of APW enrichment culture and plating onto CHROMagar Vibrio and TCBS agars. Compared with V. parahaemolyticus isolation using the conventional culture test, LAMP results showed 100% (30/30) and 90.8% (128/141) sensitivity and specificity, respectively. The conventional culture test required more than 3 days to isolate and identify V. parahaemolyticus in the APW enrichment culture. In contrast, the LAMP assay was markedly faster, requiring less than 60 min from the beginning of DNA extraction to final detection of V. parahaemolyticus. In total, the LAMP assay required 17–19 h from the beginning of enrichment culture to final determination. This is the first report of the LAMP assay for rapid screening of seafood samples naturally contaminated by V. parahaemolyticus. [Copyright &y& Elsevier]

Abstract: High quality (glyco)proteins are needed for biopharmaceutical applications. They are generally expressed as recombinant proteins in bacteria, yeast, plant and/or animal cells in culture. Growth media are increasingly supplemented with peptones to improve either the cell growth or protein expression or both. To further enhance protein production, it is important to understand the effects of peptones at the cellular and molecular levels. Upon addition of a soy peptone to a cultivation medium of CHO cells, an increased specific productivity was observed. This work aimed at elucidating which main cellular functions are affected by the presence of the peptone. Therefore, hypotheses about putative effects on recombinant protein production steps have been postulated and tested. Although the effects emerge to be multiple, it was found that the peptone increased overall protein translation and recombinant protein secretion. Nonetheless, when other cellular functions (e.g. transcription, glycosylation, proteolytic degradation) were examined, no specific effects were observed. Further experiments are needed to probe the mechanisms related to the influence of the soy peptone on these cellular functions. [Copyright &y& Elsevier]

The cell wall of Candida albicans is central to the yeasts ability to withstand osmotic challenge, to adhere to host cells, to interact with the innate immune system and ultimately to the virulence of the organism. Little is known about the effect of culture conditions on the cell wall structure and composition of C. albicans. We examined the effect of different media and culture temperatures on the molecular weight (Mw), polymer distribution and composition of cell wall mannan and mannoprotein complex. Strain SC5314 was inoculated from frozen stock onto yeast peptone dextrose (YPD), blood or 5% serum agar media at 30 or 37°C prior to mannan/mannoprotein extraction. Cultivation of the yeast in blood or serum at physiologic temperature resulted in an additive effect on Mw, however, cultivation media had the greatest impact on Mw. Mannan from a yeast grown on blood or serum at 30°C showed a 38.9 and 28.6% increase in Mw, when compared with mannan from YPD-grown yeast at 30°C. Mannan from the yeast pregrown on blood or serum at 37°C showed increased Mw (8.8 and 26.3%) when compared with YPD mannan at 37°C. The changes in Mw over the entire polymer distribution were due to an increase in the amount of mannoprotein (23.8–100%) and a decrease in cell wall mannan (5.7–17.3%). We conclude that C. albicans alters the composition of its cell wall, and thus its phenotype, in response to cultivation in blood, serum and/or physiologic temperature by increasing the amount of the mannoprotein and decreasing the amount of the mannan in the cell wall. [ABSTRACT FROM PUBLISHER]

Abstract: Detection of Escherichia coli O157:H7 by conventional cultural methods can be difficult in food matrices with a high background flora such as raw ground beef. Raw ground beef samples, artificially contaminated separately with five strains of E. coli O157:H7 at low (~0.2cfu/g) and high (~2cfu/g) levels, were enriched by two enrichment protocols; buffered peptone water (BPW) at 37°C for 5h and 24h and modified buffered peptone water with pyruvate (mBPWp) for 5h at 37°C followed by adding selective agents and incubating at 42°C to 24h. Detection of added E. coli O157:H7 by real-time PCR (RTiPCR) and recovery on isolation agars was performed before and after PATHATRIX™ immunomagnetic separation (IMS). RTiPCR detection and cultural recovery of inoculated E. coli O157:H7 after 5h enrichment were poor at 0.21–0.24cfu/g. The addition of IMS after 5h enrichment did not improve RTiPCR detection but markedly improved recovery by culturing. By extending enrichment to 24h, RTiPCR detection improved to 76% for either enrichment protocol without IMS. When 24h enrichment was followed by IMS, RTiPCR detection was also further improved. Cultural recovery after 24h enrichment was 56% and 84% without IMS and 100% and 92% after IMS for BPW and mBPWp respectively. Extended enrichment to 24h followed by IMS was found to be sensitive and reliable for detection and cultural recovery from raw ground beef using either enrichment method. [Copyright &y& Elsevier]

An extreme thermophilic ethanol-producing strain was isolated from an ethanol high-yielding mixed culture, originally isolated from a hydrogen producing reactor operated at 70 WC. Ethanol yields were assessed with increasing concentrations of xylose, up to 20 g/l. The ability of the strain to grow without nutrient addition (yeast extract, peptone and vitamins) was also assessed. The maximum ethanol yield achieved was 1.28 molethanol/molxylose consumed (77% of the theoretical yield), at 2 g/l of initial xylose concentration. The isolate was able to grow and produce ethanol as the main fermentation product under most of the conditions tested, including in media lacking vitamins, peptone and yeast extract. The results indicate that this new organism is a promising candidate for the development of a second generation bio-ethanol production process. [ABSTRACT FROM AUTHOR]

Coconut water (CW) is a by-product of food industry and has little value in Thailand. It is usually discarded as a waste into the environment. Consequently, we developed a value added process of exopolysaccharide (EPS) production using Lactobacillus confusus TISTR 1498 and coconut water. The effect of three expensive supplements (peptone, yeast extract and beef extract) on EPS and biomass production was investigated at 35°C for 24 h. Using a mod-MRS-CW medium, prepared by replacing the de-ionized water with 100% CW and supplemented with 20 g/l crystalline sucrose and a reduced quantity (50%) of the three expensive supplements (5 g/l of peptone, 2.5 g/l of yeast extract, and 2.5 g/l of beef extract) gave the highest yield of EPS (12.3 g/l). By optimizing the conditions for fermentation (pH 5.5, agitation speed at 50 rpm and initial sucrose concentration of 100 g/l), EPS yield increased up to 38.2 g/l. When compared with the modified MRS medium, the medium supplemented with CW was found to be suitable for the reduction of cost spent on the organic nitrogen and growth factors (savings close to 50%). [ABSTRACT FROM AUTHOR]

In this report, possible utilization of a chromium-reducing bacterial strain Cellulosimicrobium cellulans KUCr3 for effective bioremediation of hexavalent chromium (Cr(VI))-containing wastewater fed with tannery effluents has been discussed. Cr(VI) reduction and bioremediation were found to be related to the growth supportive conditions in wastewater, which is indicative of cell mass dependency for Cr(VI) reduction. Cr(VI) reduction was determined by measuring the residual Cr(VI) in the cell-free supernatant using colorimetric reagent S-diphenylcarbazide. Nutrient availability and initial cell density showed a positive relation with Cr(VI) reduction, but it was inhibited with increasing concentration of Cr(VI) under laboratory condition. The optimum temperature and pH for effective Cr(VI) reduction in wastewater were found to be 35°C and 7.5, respectively. The viable cells of KUCr3 were successfully entrapped in an agarose bead that was used in continuous column and batch culture for assaying Cr(VI) reduction. In packed bed column (continuous flow) experiment, approximately 25% Cr(VI) reduction occurred after 144 h. Cr(VI) was almost 75% and 52% reduced at concentrations of 0.5 mM and 2 mM Cr(VI), respectively, after 96 h in batch culture experiment in peptone-yeast extract-glucose medium, whereas it could decrease the Cr(VI) content up to 40% from the water containing tannery waste. This study suggests that KUCr3 could be used as a candidate for possible environmental clean up operation with respect to Cr(VI) bioremediation. [ABSTRACT FROM AUTHOR]

To study thraustochytrids from temperate and cold environments of Southern Argentina, the standard cultivation methodologies have been modified because many of the microorganisms detected by microscopic examination in both the original samples and the colonized baits failed to be successfully isolated in standard culture media. As a result, 35 strains, most of them having a very low growth rate, were isolated. Alternative procedures are proposed according to the nature of the sample, the characteristics of the thraustochytrid to be isolated, and the presence of contaminating microorganisms. Modifications proposed include the use of a newly formulated culture medium (Mar Chiquita, containing glucose, gelatine hydrolysate, peptone, and corn steep liquor as main carbon and nitrogen sources). In addition, the effects of the nutrient composition and agar concentration of culture media on the relative growth rates of the isolates were studied in an attempt to determine the most suitable conditions for the cultivation of new strains of thraustochytrids. The goal of this study is to develop a standard methodology, allowing us to grow baitable 'elusive' thraustochytrid strains, and that could be applied to improve the isolation and the study of the undocumented biodiversity of this group of microorganisms from different environments. [ABSTRACT FROM AUTHOR]

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Amylases and cellulases are important enzymes that can be utilized for various biological activities. Ten different wild Nigerian mushrooms (Agaricus blazei, Agaricus sp., Corilopsis occidentalis, Coriolus versicolor, Termitomyces clypeatus, Termitomyces globulus, Pleurotus tuber-regium, Podoscypha bolleana, Pogonomyces hydnoides, and Nothopanus hygrophanus) were assayed for production of these secondary metabolites. The results revealed that most of the tested wild fungi demonstrated very good amylase and cellulase activities. With the incorporation of carboxymethyl-cellulose (a carbon source) into the culture medium, Agaricus blazei had the highest amylolytic activity of 0.60 unit/mL (at 25°C, pH 6.8). This was followed in order by P. tuber-regium and Agaricus sp. with 0.42 and 0.39 unit/mL, respectively (p ⩽ 0.05). Maltose and sucrose supplementation into the submerged liquid medium made N. hygrophanus and P. hydnoides to exhibit very low amylase activities of 0.09 and 0.11 unit/mL, respectively. Introducing peptone (an organic nitrogen source) into the basal medium enhanced the ability of C. versicolor to produce a cellulase value of 0.74 unit/mL. Other organic nitrogen sources that supported good cellulase activities were yeast extract and urea. Sodium nitrate (inorganic nitrogen source) generally inhibited cellulase production in all mushrooms. The best carbon source was carboxymethyl-cellulose, which promoted very high cellulase activity of 0.67 unit/ mL in C. versicolor, which was followed in order by P. tuber-regium, T. chypeatus, and C. occidentalis (p ⩽ 0.05). Sucrose was the poorest carbon compound, supporting the lowest values of 0.01, 0.01, and 0.14 unit/mL in P. hydnoides, A. blazei, and Agaricus sp., respectively. [ABSTRACT FROM AUTHOR]

Our main objective was to optimize the enrichment of Escherichia coli O26 in raw milk cheeses for their subsequent detection with a new automated immunological method. Ten enrichment broths were tested for the detection of E. coli O26. Two categories of experimentally inoculated raw milk cheeses, semi-hard uncooked cheese and 'Camembert' type cheese, were initially used to investigate the relative efficacy of the different enrichments. The enrichments that were considered optimal for the growth of E. coli O26 in these cheeses were then challenged with other types of raw milk cheeses. Buffered peptone water supplemented with cefixim-tellurite and acriflavin was shown to optimize the growth of E. coli O26 artificially inoculated in the cheeses tested. Despite the low inoculum level (1-10 CFU per 25 g) in the cheeses, E. coli O26 counts reached at least 5·10 CFU ml after 24-h incubation at 41·5°C in this medium. All the experimentally inoculated cheeses were found positive by the immunological method in the enrichment broth selected. Optimized E. coli O26 enrichment and rapid detection constitute the first steps of a complete procedure that could be used in routine to detect E. coli O26 in raw milk cheeses. [ABSTRACT FROM AUTHOR]

Fish processing generates large amounts of solid and liquid wastes. Many different by-products have been produced from fish processing wastes. Studies on solubilization of Bolti fish ( Tilapia nilotica) viscera by endogenous enzymes at different pHs are described. Hydrolysis reactions were conducted with freshly thawed viscera utilizing an initial temperature gradient and terminated at various time points by heat inactivation of the enzymes. Various peptones obtained from hydrolysed visceral homogenates of Bolti fish residues showed their suitability for promoting the growth of lactic acid bacteria (mainly Lactobacillus sake Lb 706), microorganisms with particularly complex nutritional requirements especially peptidic sources. The assay of several treatments with L. sakei Lb 706, producer of the bacteriocin sakacin A, demonstrated that optimum conditions for biomass and bacteriocin production only imply a brief autohydrolysis at room temperature. The results showed that the Bolti fish hydrolysates gave remarkable results to those found in costly commercial media, specifically recommended for culturing and large-scale production of lactic acid bacteria. [ABSTRACT FROM AUTHOR]

Abstract: Glucose addition to glucose-starved Saccharomyces cerevisiae cells triggers a quick and transient influx of calcium from the extracellular environment. In yeast at least two different carrier systems were identified: a high affinity system, requiring Cch1 channel, and a low affinity system. Here we report that another calcium transport system exists in yeast, not yet identified, that can substitute the two known systems when they are inactivated. This system was called GIC (for Glucose Induced Calcium) system and it is a high affinity calcium transport system, magnesium-sensitive but nickel-resistant. Moreover, GIC transport is sensitive to gadolinium and nifedipine, but it is not sensitive to inhibition by verapamil, which conversely behaves as an agonist on glucose response. GIC transport is fully functional in conditions when calcineurin is active, a serine/threonine specificity phosphatase involved in the regulation of calcium homeostasis and in many other cellular phenomena such as tolerance to high concentrations of Na+ and Li+, response to pheromones and gene transcription regulation. Here it is reported for the first time that calcineurin can also be activated by nutrients: the activation of Crz1 transcription factor by calcineurin was observed in derepressed cells after addition of glucose in the presence of extracellular calcium. [Copyright &y& Elsevier]

Abstract: Yeast prion [PSI +] is a self-perpetuating amyloid of the translational termination factor Sup35. Although [PSI +] propagation is modulated by heat shock proteins (Hsps), high temperature was previously reported to have little or no effect on [PSI +]. Our results show that short-term exposure of exponentially growing yeast culture to mild heat shock, followed by immediate resumption of growth, leads to [PSI +] destabilization, sometimes persisting for several cell divisions after heat shock. Prion loss occurring in the first division after heat shock is preferentially detected in a daughter cell, indicating the impairment of prion segregation that results in asymmetric prion distribution between a mother cell and a bud. Longer heat shock or prolonged incubation in the absence of nutrients after heat shock led to [PSI +] recovery. Both prion destabilization and recovery during heat shock depend on protein synthesis. Maximal prion destabilization coincides with maximal imbalance between Hsp104 and other Hsps such as Hsp70-Ssa. Deletions of individual SSA genes increase prion destabilization and/or counteract recovery. The dynamics of prion aggregation during destabilization and recovery are consistent with the notion that efficient prion fragmentation and segregation require a proper balance between Hsp104 and other (e.g., Hsp70-Ssa) chaperones. In contrast to heat shock, [PSI +] destabilization by osmotic stressors does not always depend on cell proliferation and/or protein synthesis, indicating that different stresses may impact the prion via different mechanisms. Our data demonstrate that heat stress causes asymmetric prion distribution in a cell division and confirm that the effects of Hsps on prions are physiologically relevant. [Copyright &y& Elsevier]

Abstract: 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 8g/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. [Copyright &y& Elsevier]

Species identification is important for epidemiological, clinical and treatment purposes. The aim of this study was to find out whether hippurate hydrolysis is a reliable test for differentiating between Campylobacter coli and Campylobacter jejuni. To achieve this, hippurate hydrolysis test was compared with multiplex Polymerase Chain Reaction (mPCR) for their ability to speciate C. coli and C. jejuni. Eighteen Campylobacter strains from poultry samples were used for this study. The results from 17 of the 18 strains were in agreement with both methods. Thus, the hippurate hydrolysis test can be used for distinguishing C. jejuni from C. coli although occasionally some strains of C. jejuni may be mis-identified as C. coli. [ABSTRACT FROM AUTHOR]

Abstract: Marine natural products with biological activity represent an important resource for marine drugs and biotechnological products; however, most marine natural products, especially those derived from sponges, have not been further developed because of the limited number of sources. The scale-up cultivation of the microbial source of sponge-derived natural products could provide a possible approach to solve this bottleneck problem. In this study, statistical Plackett–Burman (PB) design and Box–Behnken response surface methodology (RSM) were used to optimize the medium components to increase the production of bacillamide C by the Bacillus atrophaeus strain C89, which was associated with the marine sponge Dysidea avara. The obtained optimal medium consisted of 3.64g/L corn starch, 6.29g/L CaCO3, 4.00g/L soy peptone, 6.00g/L peptone, 0.10g/L cysteine and 0.02g/L tryptophan with artificial sea water (ASW). Using this optimized medium, the concentration of bacillamide C reached 70.85mg/L in fed-batch cultivation in a 5-L fermentor at pH 7.70, which was 25.80-fold higher than the level observed in a shake flask using the basic medium. This study provides a potential approach for the production of bacillamide C and related derivatives, which was the first to optimize the cultivation of sponge-associated microbes for the production of marine natural products. [Copyright &y& Elsevier]

Abstract: The goal of the present work was to study the efficacy of several lactic acid bacteria (LAB) as bio-silage inoculants of swordfish, ray and shark viscera by-products. A sterilised medium was initially used as a model system for assessing the potential of these microorganisms in batch and fed-batch cultures with re-neutralisation. In all cases, batch cultivations without re-neutralisation led to the highest production and yields of the main metabolites of LAB fermentation (lactic and acetic acids). The dynamics of these metabolites followed a conversion pattern from lactic to acetic acid with a final joint concentration over 16g/L and final pH lower than 4.5. Both productions were modelled by means of logistic modified equations. In addition, the capability of LAB to ferment the fish visceral wastes was always high and easily reproducible. Finally, the results obtained for non-sterilised fermentations with Lactobacillus casei CECT 4043 were similar to those obtained for sterilised media, and a stable material was obtained after 72h of culture. [ABSTRACT FROM AUTHOR]

Abstract: Extraction of proteose–peptones (PPs) was carried out from fresh milk, from milk after prolonged incubation (12 days at 37 °C) and from two different whey protein concentrates (WPCs). The high performance liquid chromatography profiles of these extracts were compared. PPs eluted as three chromatographic peaks, which increased during milk incubation. The PP extracts from WPCs showed a number of peaks that are attributable to small peptides belonging to the proteose–peptone fraction and probably derive from proteolysis during storage of WPC. The dynamic properties at the air–water interface of the PP extracts were investigated by the drop-volume method. The PPs extracted from fresh milk showed the lowest values and a more rapid reduction in surface tension. PPs from WPCs were found to be effective as surfactants, even though a less marked reduction in surface tension compared with PPs from milk samples was shown. [Copyright &y& Elsevier]

Detergent compatible alkaline protease production by a newly isolated Bacillus sp.Y from laundry soil was studied under shake flask conditions in growth medium comprised (g/L): peptone, 1; NaCl, 5; skim milk, 100; Na2CO3, 4. Different environmental process parameters such as fermentation period, initial pH, incubation temperature, and nutritional parameters such as supplementation of different starch sources and nitrogen sources were standardized for the maximum yield of alkaline protease. Rice flour showed an almost 2.2-fold increase in protease activity followed by wheat flour, which showed a 1.85-fold increase over the basal media. However, supplementation of potato starch, corn starch, and ragi exerted an inhibitory effect on alkaline protease production. Protease production by Bacillus sp. Y was suppressed up to 80% in the presence of most of the organic and inorganic nitrogen sources tested in comparison to rice flour:peptone supplementation. Hence, based on the optimization studies, we achieved a yield of 88 PU/mL (2.2-fold increase) with the Bacillus sp. Y when cultivated for 72 h at pH 7.5, 37 °C in a medium containing: rice flour (1%, w/v), NaCl (0.5%, w/v), and skim milk (10%, v/v) with Na2CO3 (0.4%, w/v). [ABSTRACT FROM AUTHOR]

In this article, a quantitative real-time PCR assay for detection and enumeration of the spoilage yeast Dekkera anomala in beer, cola, apple cider, and brewing wort is presented as an improvement upon existing detection methods, which are very time-consuming and not always accurate. Primers were designed to exclude other organisms common in these beverages, and the assay was linear over 6 log units of cell concentrations. The addition of large amounts of non-target yeast DNA did not affect the efficiency of this assay. A standard curve of known DNA was established by plotting the C values obtained from the QPCR against the log of plate counts on yeast peptone dextrose medium and unknowns showed exceptional correlation when tested against this standard curve. The assay was found to detect D. anomala at levels of 10-14 CFU ml in either cola or beer and at levels of 9·4-25·0 CFU ml in apple cider. The assay was also used to follow the growth of D. anomala in brewing wort. The results indicate that real-time PCR is an effective tool for rapid, accurate detection and quantitation of D. anomala in beer, cola and apple cider. This method gives a faster and more efficient technique to screen beer, cola, and cider samples and reduce spoilage by D. anomala. Faster screening may allow for significant reduction in economic loss because of reduced spoilage. [ABSTRACT FROM AUTHOR]

The objective of this study was to produce fish peptone (FP) from silver carp (Hypophthalmichthys molitrix) heads by Alcalase® hydrolysis in order to use for growing Vibrio anguillarum instead of the standard peptones applied in the commercial media. An optimization of the FP to be used as culture media was also carried out using the response surface method (RSM). According to the results, the degree of hydrolysis and protein percentage after 24 h was 37.68 mg/mL and 20.74%, respectively. The adjustment of the quadratic model with the experimental data was satisfactory. The analysis of variance showed a high coefficient of determination value (0.930). The results of fish protein hydrolysates also showed that fish by-products modified by enzymatic procedures can be used as low cost nitrogen sources for bacterial growth. [ABSTRACT FROM AUTHOR]

Abstract: Ligninolytic enzymes activities (laccases, peroxidases (total, MnP and MiP) and aryl-alcohol oxidase (AAO)) were measured during the cultivation of six commercial Pleurotus sp. strains on MMP media, on cereal grains (spawn) and on straw substrates (the three commonly utilized cultivation steps to obtain fruiting bodies) supplemented with several concentrations of autoclaved (OMW) or gamma-irradiated (iOMW) olive mill waste. Results indicated that all the strains were able to grow on MMP media and spawn containing up to 30% OMW and iOMW and on straw substrates mixed with 50% OMW. None of the strains showed AAO activity and there was not a single strain which showed the highest laccases and peroxidases activities, independently of the utilized substrate. Pleurotus mycelia adjusted their enzymatic mechanisms depending on their variety, type of substrate, concentration of OMW or iOMW added. OMW was a better supplement to use than iOMW because OMW induced higher exo-enzymes activities. [Copyright &y& Elsevier]

This study aimed at optimising the cultivation conditions for the production of carotenoids by Sporidiobolus salmonicolor (CBS 2636) in a bioreactor. The maximum content of total carotenoids in the full factorial design 2² was 3131.3 μg/L in synthetic medium with 80 g/L of glucose, 15 g/L of peptone, 5 g/L of malt extract, aeration of 1.5 vvm, agitation of 180 rpm, initial pH of 4.0 at 25 °C. In the kinetic study, we could observe that the bioproduction of carotenoids is associated with cell growth in the exponential phase, and the average specific growth (μ) in bioreactor is 0.046 h with a maximum yield of 0.19 g cells/L h. The maximum yield of carotenoids (60.0 μg/Lh) is observed at 50-h bioproduction. The conversion factor for total organic carbon (TOC) in cells (Y/) was 2.97 g/g (0-50 h) and 0.254 g/g (50-100 h), the conversion factor glucose into cells (Y) was 0.168 g/g (0-100 h). The specific production of carotenoids (Y/) was 390 μg of carotenoids per gram of cells, the conversion factor of carbon in the product (Y) was 107.8 μg/g (0-50 h) and 34.4 μg/g (50-100 h), whereas the factor Y/ was 69.59 μg/g. The agitation and aeration provided better homogeneity in the culture medium, and hence greater availability of nutrients and oxygen, leading to higher production of carotenoids. [ABSTRACT FROM AUTHOR]

Abstract: While bacteria and yeast are used for the production of rather simple proteins, mammalian cells are generally required for the production of more complex proteins (i.e. post-translational modifications and, in particular, complex glycosylations). In order to boost cell growth and protein production, cultivation media are commonly supplemented with plant peptones, which are hydrolysed plant proteins. Therefore, plant peptones consist mainly of an undefined mixture of peptides, but also contain carbohydrates, phenolic compounds, salts, etc. To increase biosafety, the current trend is the use of chemically defined media. The straightforward idea that only a small number of compounds from peptones are biologically active is attractive, but their identification remains challenging. We first characterised global chemical families of compounds present in a soy peptone. The main constituents of this batch were peptides (60%) and carbohydrates (20%). The addition of this peptone or derived fractions to the culture medium was then tested on Chinese hamster ovary cells, CHO-320 line, expressing γ-interferon (γ-IFN), cultivated in BDM. Its presence did not increase the time-integral of the viable cell density, it increased slightly that of the γ-IFN concentration, but significantly the product/cell yield. Upon fractionation of this peptone by anion exchange chromatography and gel filtration, beneficial and detrimental fractions were obtained. The antioxidant activity of detrimental fractions was higher than that of beneficial fractions. Whereas the chemical nature of antioxidants contained in the detrimental fractions remains unknown, it may be assumed that they could inhibit the proliferation of CHO cells. Although the beneficial compounds were not identified, a fraction exhibiting the same effect as the peptone, but less complex, was obtained. [Copyright &y& Elsevier]

Monascus-fermented products have been widely used in Taiwan and other Asian countries as health foods. Unfortunately, many Monascus strains concurrently produce trace amounts of toxic citrinin. This study isolated a strain NPUST-B11 with the ability to degrade citrinin as the only carbon source. The isolated strain NPUST-B11 was characterised and identified as Klebsiella pneumoniae by 16S rRNA gene analysis using UNI-F and UNI-R primers. The isolated strain was then incubated in the mineral broth containing 10 ppm of citrinin, 1.2% of glucose, 0.3% of peptone and 100 ppm of vitamin C under optimal conditions, including pH 7, 200 rpm and 37°C. Citrinin was rapidly degraded with incubation from 97.9% at 1 h to 8.67% at 5 h and completely depleted at 10 h. Overall, this strain could be useful for the degradation of citrinin in food products and other medical applications. [ABSTRACT FROM AUTHOR]

The effect of different carbon and nitrogen sources on the production of mannan-degrading enzymes, focussing on β-mannanase, by Aspergillus niger was investigated using shake flask culture. The β-mannanase activity obtained during growth of A. niger on guar gum (GG, 1495nkatmL−1) was much higher than those observed on other carbon substrates, locust bean gum (1148nkatmL−1), α-cellulose (10.7nkatmL−1), glucose (8.8nkatmL−1) and carboxymethylcellulose (4.6nkatmL−1). For fermentation using GG as a carbon source, bacteriological peptone gave the highest β-mannanase activity (1744nkatmL−1) followed by peptone from meat (1168nkatmL−1), yeast extract (817nkatmL−1), ammonium sulphate (241nkatmL−1), ammonium nitrate (113nkatmL−1) and ammonium chloride (99nkatmL−1) when used as a nitrogen source. The composition of bacteriological peptone and initial pH of the medium were further optimized using response surface methodology (RSM). Medium consisted of 21.3gL−1 GG and 57gL−1 peptone with initial culture pH of 5.5 was optimum for β-mannanase production (2063nkatmL−1) by A. niger. The β-mannanase production obtained in this study using A. niger was significantly higher than those reported in the literature. [ABSTRACT FROM AUTHOR]

Abstract: The capacity to detect low levels of healthy and sub-lethally injured Salmonella enterica cells in chocolate by two alternative rapid detection methods iQ-CheckTM Salmonella II real-time PCR (Bio-Rad) and VIDAS® Easy SLM (BioMérieux) was assessed and compared with ISO 6579:2005. Chocolate, a low moisture food known to support the survival of Salmonella, was challenged as food matrix. Buffered peptone water (BPW) did not support the recovery of low levels of sub-lethally injured S. enterica independent of the detection method, while BPW supplemented with milk powder enabled detection by the three examined methods. However, inhibition of real-time PCR was observed since for one out of three repetitions of chocolate inoculated with a low number of sub-lethally injured S. enterica cells, no PCR signal was obtained. Therefore, attention should be paid to the enrichment step to avoid false negative results due to the presence of especially sub-lethally injured Salmonella cells in chocolate. An appropriate sample preparation (such as enrichment media and conditions for incubation) remains the key factor for reliable detection including sub-lethally injured cells and should be evaluated, if necessary optimized, for each detection assay. [Copyright &y& Elsevier]

Abstract: The work aimed to develop a “true headspace-SPME–GC” method for evaluating the aroma retention capacity of the proteose–peptone (PP) milk protein fraction. The SPME analytical conditions were optimized in aqueous solution to which was added a blend containing seven aroma compounds from different chemical classes. The following parameters were tested: sample equilibrium time, fibre coating and fibre exposure time. The optimal equilibrium time was found to be 4h and the DVB/CAR/PDMS fibre offered the highest sensitivity and repeatability. Finally, a 1min fibre exposure time was chosen in order to avoid aroma competition and extraction phenomena. This method was then employed to evaluate the flavour binding capacity of PP aqueous systems at different pH values (6.8, 5.0 and 3.8). For all the pH conditions the retention capacity of the PP fraction gradually increased with hydrophobic chain length or overall hydrophobicity of the aroma compounds. Higher aroma binding capacity was found at pH 3.8. [Copyright &y& Elsevier]

Effect of culture conditions on biomass, lipid, and arachidonic acid production was investigated in the oleaginous fungus Mortierella alpina CBS 528.72 under shake flask conditions. Several factors have been found to affect the biomass buildup and lipogenesis in this fungus, complicated by the fact that different strains demonstrate varying optimization conditions. Growth, lipid accumulation, and arachidonic acid production in the strain investigated were influenced by media, pH, temperature, carbon source, nitrogen source, etc. The results indicated that the most effective medium for growth and arachidonic acid production was glucose yeast extract medium. The optimum pH and temperature were found to be 6.5 and 28°C, respectively. On the same weight basis, glucose was the most efficient carbon source for biomass and lipid production in this fungal strain which yielded 6.8 g/L dry biomass and 40.2% ( w/ w) total lipid after 7 days of cultivation. Maximum arachidonic acid (ARA) production of 40.41% achieved in rhamnose-containing media was not concomitant with higher biomass and lipid yields. Efficacy of organic carbon sources, viz, yeast extract and peptone over inorganic sources like sodium nitrate, ammonium sulfate, ammonium chloride, etc, was established in the present study. M. alpina CBS 528.72 grown in peptone acquired the highest lipid content (42.0% ( w/ w)). However, the ARA content (28.74%) proved to be significantly less than that grown in yeast extract (35.28%). Furthermore, it was found that the biomass and ARA production declined drastically in a medium with vegetable oils as the sole carbon source but triggered the lipogenic pathway leading to higher accumulation of total lipids. Under the ideal conditions mentioned above, the maximum biomass, total lipid, and arachidonic acid production were 6.8 g/L, 41.6%, and 35.28% total fatty acid, respectively, in shake flask system. [ABSTRACT FROM AUTHOR]

Riboflavin producing lactic acid bacteria were isolated from fermented milk samples. Lactobacillus fermentum MTCC 8711, which produced higher amount of riboflavin, was used for the fermentative production of riboflavin. Response surface methodology with central composite design was used for the optimization of the fermentation medium for riboflavin production. Peptone, beef extract, glucose and K2HPO4 of the MRS broth were selected as variables. Among the tested variables, beef extract, glucose and K2HPO4 showed significant effect on the riboflavin production. Higher concentration of K2HPO4 exhibited positive response on riboflavin production. The validation run based on the optimum production in response surface plot resulted in the maximum (9.43 mg L-1) riboflavin yield, which was almost equivalent to the predicted value of 9.63 mg L-1. The Lb. fermentum strain produced four folds higher riboflavin in the optimized medium when compared to the unoptimized medium (2.28 mg L-1). [ABSTRACT FROM AUTHOR]

In an effort to optimize the medium components, the statistical methodology was applied to achieve the optimum lipase production under shake flask conditions. The study was conducted in three steps on newly isolated Bacillus pumilus RK 31. In the first step, 12 different variables viz., Glucose, Olive oil, Yeast extract, Peptone, Tween 80, KH2PO4, MgSO4, NaNO3, CaCl2, Temperature, pH and Inoculum size were used to identify the most significant variables affecting lipase production using Plackett–Burman statistical design. Variance analysis showed that Olive oil, Tween 80 and KH2PO4 played significant role in lipase production. In the second step, the values of the above-identified three variables were optimized by central composite design using three-level-three-factor approach. The optimum values of Olive oil, Tween 80 and KH2PO4 were found to be 10.0ml/l, 5.0ml/l and 8.0g/l, respectively. KH2PO4 was found to be responsible for maximum lipase production of 5.59IU/ml, experimental and 5.03IU/ml, predicted. In the third step, the optimum predicted values of the three factors and lipase production were verified by experimental approach. The amount of lipase produced in the designated medium was in agreement with that of predicted values by statistical method. [Copyright &y& Elsevier]

Abstract: Acidithiobacillus ferrooxidans strain SRDSM2 was isolated from silica containing soil sample collected at a Rajpardi lignite mine. The strain responded to the addition of 0.5g/L peptone and 1.0g/L tryptone soya broth in the ferrous sulphate tryptone soya broth (ITSB) medium with 35.3% and 29.6% increase in iron oxidation rate (IOR), but decrease in the IOR at higher peptone or tryptone soya broth levels. The presence of 4mM of zinc as zinc sulphate in the medium increased the IOR by 24.4%. Forty percent of the inoculated cells survived even after exposure at 80°C for 120min and showed 30% ferrous iron oxidation. The V max and K s for iron oxidation by the isolate were 344.82mg/L/h and 32.25g/L respectively. The isolate was able to oxidized ferrous iron even in presence of 4.06M ionic strength of medium and leached >85% copper and zinc from the polymetallic concentrate. Thus, this isolate can be used for bioextraction of metals from polymetallic concentrate. [ABSTRACT FROM AUTHOR]

Abstract: This study evaluated the kinetics of simultaneous biodegradation of peptone mixture and 2,6-dihydroxybenzoic acid (2,6-DHBA) by an acclimated dual microbial culture under aerobic conditions. A laboratory-scale sequencing batch reactor was sustained at steady-state with peptone mixture feeding. During the study period, peptone mixture feeding was continuously supplemented with 2,6-DHBA. Related experimental data were derived from three sets of parallel batch reactors, the first fed with the peptone mixture, the second with 2,6-DHBA and the third one with the two substrates, after acclimation of microbial culture and simultaneous biodegradation of both organics. A mechanistic model was developed for this purpose including the necessary model components and process kinetics for the model calibration of relevant experimental data. Model evaluation provided all biodegradation characteristics and kinetics for both peptone mixture and 2,6-DHBA. It also supported the development of a dual microbial community through acclimation, with the selective growth of a second group of microorganisms specifically capable of metabolizing 2,6-DHBA as an organic carbon source. [ABSTRACT FROM AUTHOR]

Glucose oxidase (GO) is an enzyme that is used in many fields. In this study, ram horn peptone (RHP) was utilized as the nitrogen source and compared with other nitrogen sources in the production of GO by Aspergillus niger. To obtain higher GO activity, 14 A. niger strains were isolated from soil samples around Erzurum, Turkey. Among these strains, the isolate that was named A. niger OC-3 achieved the highest GO production. The production of GO was carried out in 100 mL scaled batch culture. The fermentation conditions such as initial pH, temperature, agitation speed, and time were investigated in order to improve GO production. The results showed that the cultivation conditions would significantly affect the formation of GO, and the utilization of the RHP achieved the highest enzyme production (48.6 U/mL) if compared to other nitrogen sources. On the other hand, the maximum biomass was obtained by using the fish peptone (7.2 g/L), while RHP yielded 6.4 g/L. These results suggest that RHP from waste ram horns could effectively be used in the production of GO by A. niger OC-3. [ABSTRACT FROM AUTHOR]

The main purpose of this study is to reduce the production cost of cellulase by optimizing the production medium and using an alternative carbon source such as municipal solid waste residue. In the present investigation, we aim to isolate the two novel cellulase producing fungi (Aspergillus niger and Trichoderma sp.) from municipal solid waste. Municipal solid waste residue (4-5% (w/v)) and peptone and yeast extract (1.0% (w/v)) were found to be the best combination of carbon and nitrogen sources for the production of cellulase by A. niger and Trichoderma sp. Optimumtemperature and pH of the medium for the cellulase production by A. niger were 40?C and 6-7, whereas those for the production of cellulase by Trichoderma sp. were 45?C and 6.5. Cellulase production from A. niger and Trichoderma sp. can be an advantage as the enzyme production rate is normally higher as compared to other fungi. [ABSTRACT FROM AUTHOR]

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 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 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. [ABSTRACT FROM AUTHOR]

Production of 3,4-dihydroxy phenyl- l-alanine ( l-DOPA) using an Egyptian isolate of halophilic black yeast was studied. Optimum aeration level and incubation period for high yield production of l-DOPA were 50 ml medium/250 ml flask with 200 rpm and 36 h, respectively. Two new techniques (addition of aniline or NaCl to the medium) have been investigated to enhance the monophenolase activity and inhibit or reduce diphenolase activity of tyrosinase to form high yield of l-DOPA without more oxidation to melanin. Addition of aniline to tyrosine medium at 3 μl/ml medium enhanced l-DOPA production 2.9 fold, however, addition of NaCl at 20% showed the same amount of l-DOPA as the control. Peptone and ram horn hydrolysate were studied as nitrogen sources instead of tyrosine in the medium and they showed good nitrogen sources for l-DOPA production as tyrosine. Finally, addition of aniline (3 μl/ml) to ram horn hydrolysate was economically feasible and cost effective for l-DOPA production by Egyptian halophilic black yeast. [ABSTRACT FROM AUTHOR]

Biosurfactant production was screened in four lactobacilli strains. The highest biosurfactant production (excreted and cellbound biosurfactants) was achieved with Lactobacillus paracasei ssp. paracasei A20, a strain isolated from a Portuguese dairy plant, with a decrease in the surface tension of 6.4mNm-1 and 22.0mNm-1, respectively. Biosurfactant production by this strain was evaluated under different culture broth compositions. The use of different nitrogen sources revealed that yeast extract is essential for bacterial growth, while peptone is crucial for biosurfactant synthesis. For biosurfactant production, the use of peptone and meat extract yielded a higher production when compared to the standard medium, with a surface tension reduction of 24.5mNm-1. Furthermore, experiments were also conducted in a reactor with pH and temperature control. Biomass and biosurfactant production in bioreactor was higher comparing with the experiments conducted in shake flaks. The optimization procedure adopted in the current work was found to improve the biosurfactant production and opened new perspectives for the use of L. paracasei ssp. paracasei A 20 as a promising biosurfactant-producer. [ABSTRACT FROM AUTHOR]

Abstract: This study employed statistically based experimental designs to optimize fermentation conditions for hydrogen production from sweet sorghum syrup by anaerobic mixed cultures. Initial screening of important factors influencing hydrogen production, i.e., total sugar, initial pH, nutrient solution, iron (II) sulphate (FeSO4), peptone and sodium bicarbonate was conducted by the Plackett–Burman method. Results indicated that only FeSO4 had statistically significant (P ≤0.005) influences on specific hydrogen production (P s) while total sugar and initial pH had an interdependent effect on P s. Optimal conditions for the maximal P s were 25g/L total sugar, 4.75 initial pH and 1.45g/L FeSO4 in which P s of 6897mL H2/L was estimated. Estimated optimum conditions revealed only 0.04% difference from the actual P s of 6864mL H2/L which suggested that the optimal conditions obtained can be practically applied to produce hydrogen from sweet sorghum syrup with the least error. [ABSTRACT FROM AUTHOR]

Growth curves in liquid peptone-glucose medium and survival curves of the Saccharomyces cerevisiae culture from variously irradiated inoculum were evaluated. Irradiation of yeast cells in solution physiological (salt) was performed with γ-rays of Co in Gammacell 220 or with UV-irradiation using ultraviolet lamps UVH 1016-6 and Photochemical reactors, Ltd, Sylvania for various time periods. Various dose rates of both types of radiation were used. The absorbed doses reached some hundreds Gy for both γ and UV radiation. The growth curves were measured using the nephelometric data of yeast suspension in various time periods of growth. The results of repeated measurements showed that the slope of growth curves express relatively exactly the negative influence of irradiation when the standard and uniform method of evaluation was used. When the curves were fitted to the data points by the least-squares method, the average standard errors were found to be in the range from 0.6 to 0.8% and from 0.2 to 0.5% for γ- and UV-irradiation, respectively. The negative effect of irradiation depended monotonously and non-linearly on the applied dose of irradiation. Quantitatively different effects were found in the case of γ and UV irradiation. [ABSTRACT FROM AUTHOR]

This study evaluated the kinetics of 2,6-dihydroxybenozic acid and peptone biodegradation at low sludge age by acclimated culture under aerobic conditions. A laboratory-scale sequencing batch reactor was set and fed with peptone mixture. The system was operated at steady-state at a sludge age of 2 days. In order to assess biodegradation kinetics of 2,6-dihydroxybenozic acid and its impact on peptone utilization, a mixture of 2,6-dihydroxybenzoic acid and peptone was fed to mixed culture. After a period of four days, the system became acclimated to simultaneously remove both 2,6-dihydroxybenzoic acid and peptone mixture. A mechanistic model was developed involving model components and kinetic parameters for both substrates. This model was calibrated with related experimental data such as oxygen uptake rate and COD. Biodegradation characteristics and kinetics of peptone and 2,6-dihydroxybenzoic acid was estimated. The evaluation of calibrated model indicated that a group of microorganisms adjusted their enzymatic tools for the utilization of 2,6-dihydroxybenzoic acid resulting in dual microbial community development at low sludge age. [ABSTRACT FROM AUTHOR]

Influence of nitrogen source on proteinases synthesis in aerobic alkalotolerant and halotolerant bacteria from soda-salt lakes of Transbaikalia was studied. Maximal accumulation of proteinases was revealed on medium with peptones. Introduction of various sources of nitrogen in the medium did not result in increase of enzyme activity in cultural liquid. It was indicated that secreting proteinases of the studied bacteria strains possess narrow substrate specificity, hydrolyze proteins and n-nitroanilide substrates have maximal activity during GlpAALpNA hydrolysis. Data of inhibitory analysis and substrate specificity of studied extracellular enzymes indicate that they belong to a class of serine proteinases of subtilisin-like type. [ABSTRACT FROM AUTHOR]

Nattokinase was produced by batch and fed-batch culture of Bacillus subtilis in flask and fermentor. Effect of supplementing complex media (peptone, yeast extract, or tryptone) was investigated on the production of nattokinase. In flask culture, the highest cell growth and nattokinase activity were obtained with 50g/L of peptone supplementation. In this condition, nattokinase activity was 630unit/ml at 12h. In batch culture of B. subtilis in fermentor, the highest nattokinase activity of 3400unit/ml was obtained at 10h with 50g/L of peptone supplementation. From the batch kinetics data, it was shown that nattokinase production was growth-associated and culture should be harvested before stationary phase for maximum nattokinase production. In fed-batch culture of B. subtilis using pH-stat feeding strategy, cell growth (optical density monitored at 600nm) increased to ca. 100 at 22h, which was 2.5 times higher than that in batch culture. The highest nattokinase activity was 7100unit/ml at 19h, which was also 2.1 times higher than that in batch culture. [Copyright &y& Elsevier]

Metacordyceps yongmunensis is a newly reported species from Korea, which is very similar to Cordyceps species in morphological characters. It grows on large lepidopteran pupa, and numerous white stromata grow on a single host. Mycelial growth characteristics of M. yongmunensis isolates were studied in different media and at different temperatures. Also, different carbon sources, nitrogen sources, and mineral salts were tested for mycelial growth of M. yongmunensis. Schizophyllum (mushroom) genetics complete medium plus yeast extract, Schizophyllum (mushroom) genetics minimal medium, and Martin's peptone dextrose agar produced longer colony diameters and more compact mycelial density than other media. The optimum temperature for mycelial growth was 25°C. Carbon sources such as sucrose, soluble starch, dextrose, glucose, dextrin, maltose, and fructose showed better mycelial growth, whereas peptone, yeast extract and tryptone resulted in the best mycelial growth of all of the nitrogen sources tested. All of the mineral salts tested showed similar growth as the control, except K2HPO4 which showed longer colony diameter and more compact mycelial density. The compact colonies were white and cottony with a greenish margin. The results showed that M. yongmunensis is an easy fungus to growas it grew from 30 to more than 50 mm in 2 wk. [ABSTRACT FROM AUTHOR]

Abstract: The ability of the standard pre-enrichment procedure in buffered peptone water (BPW) to recover Salmonella Typhimurium from acidic marinade sauces containing spices was tested by inoculating marinade sauces with known numbers of an antibiotic-resistant marker strain of Salmonella Typhimurium DT104 prior to pre-enrichment. Viable numbers of salmonellae present in BPW after 24h incubation depended on the inoculum level. If initial cell numbers were low (below 103 cfu per 250ml BPW) final cell concentrations were also low and, in some cases, no growth occurred. The problem was overcome by use of double-strength BPW that neutralised the acidity and allowed good recovery from otherwise inhibitory marinade sauces. [Copyright &y& Elsevier]

Abstract: We previously reported that superoxide anion was generated from glucose–peptone–meat extract medium. We found that superoxide anion was generated from other conventional laboratory media, Nutrient Broth, Tryptic Soy Broth, and Mueller Hinton Broth as well as glucose–peptone–meat extract medium. The glucose–peptone–meat extract medium consisting of 1% glucose, 0.5% peptone, 0.5% meat extract, and 0.3% NaCl showed the highest superoxide anion generation among the media tested. The meat extract and peptone, which are natural nutrient sources in the medium, showed an increase in absorbance intensity by WST-1 formazan products upon reaction with superoxide anion. The specific type of reactive oxygen species was measured by SOD-inhibitable reduction of cytochrome c and WST-1 (for superoxide anion), Fluoro H2O2™ kit (for hydrogen peroxide), hydroxyphenyl fluorescein (for hydroxyl radical), and Singlet Oxygen Sensor Green (for singlet oxygen). The generation of hydroxyl radical was also evaluated by ESR-spin trapping method. We detected superoxide anion, hydrogen peroxide, and hydroxyl radical but not singlet oxygen. These results suggest that the superoxide anion spontaneously generated from glucose–peptone–meat extract medium is finally converted to hydroxyl radical. [ABSTRACT FROM AUTHOR]

Abstract: Efficient and rapid monitoring of Salmonella in the poultry production chain is necessary to assure safe food. The objective was to validate an open-formula real-time PCR method for screening of Salmonella in poultry faeces (sock samples). The method consists of incubation in buffered peptone water for 18±2h, centrifugation of a 1-ml subsample, DNA extraction on the pellet and PCR. The total analysis time is 20h. The validation study included comparative and collaborative trials, based on the recommendations from the Nordic organization for validation of alternative microbiological methods (NordVal). The comparative trial was performed against a reference method from the Nordic Committee on Food Analysis (NMKL187, 2007) using 132 artificially and naturally contaminated samples. The limit of detection (LOD50) was found to be 24 and 33CFU/sample for the PCR and NMKL187 methods, respectively. The relative accuracy, relative sensitivity and relative specificity were all 100%, when including naturally contaminated samples and samples artificially contaminated with 10–100CFU/sample. The collaborative trial included six laboratories and valid results were obtained from five of them. Apart from one of the samples that was artificially contaminated with 1–10CFU/sample being a false negative with PCR for one of the laboratories, no false-positive or false-negative results were reported. This test supplies the growing demand for validated diagnostic PCR methods for screening of samples in the meat production chain to assure safe food. [ABSTRACT FROM AUTHOR]