Peptone-yeast Extract Medium Research Articles

Evaluation of Generic Fertiliser as an Alternative Inorganic Nitrogen Source for Ethanolic Glucose Fermentation by Saccharomyces cerevisiae

In the studies and production of bioethanol, the preferred fermenting yeast (Saccharomyces cerevisiae) is usually cultured in liquid broth that contains yeast extract and peptone. However, the use of these laboratory and scientific grade chemicals is costly, making them impractical for mass bioethanol production. Therefore, this study was conducted to evaluate the feasibility of glucose ethanolic fermentation by S. cerevisiae using generic fertiliser formulations to provide inorganic nitrogen, phosphorus, potassium and trace elements (NPK-TE). Fermentation media of different generic fertiliser strength at 0.5X, 1.0X and 2.0X Fertiliser Nitrogen Equivalents (FNE), as compared to the conventional Yeast Extract-Peptone (YEP) medium as control, was used as fermentation broth during the ethanolic fermentation of glucose. Based on the results, S. cerevisiae cultured in YEP broth produced the highest cell concentration for both wet (21.93 g/L) and dry cells (3.87 g/L), with rapid increment observed in the first 72 h of fermentation. By the end of the fermentation period, lactic acid (3.14 g/L) and acetic acid (0.96 g/L) levels were recorded to be the lowest in YEP medium while their concentration (lactic acid, 8.08 g/L) and (acetic acid, 2.67 g/L) were highest in 2.0X FNE fertiliser medium. Results indicated that the best theoretical ethanol yield (TEY) among the fertiliser media was achieved when fermentation was performed in the 0.5X FNE fertiliser medium, with a TEY of 86.18%. TEY yields were 78.68% and 51.54% in broth with 1.0X and 2.0X FNE, respectively. In general, all three fertiliser media supported ethanolic fermentation of glucose, with the 0.5X FNE fertiliser broth showing a yield that is significantly close to the conventional YEP medium, as seen in the statistical analysis. Similarities in other fermentation profiles such as acetic acid, lactic acid, and biomass production, as well as glucose utilisation, between the results from the YEP samples and samples from the fertiliser broths (at 0.5X and 1.0X FNE) have also shown that generic fertiliser has the potential to be used as an alternative medium to replace the conventional YEP to produce ethanol at a lower cost.

Production of Two Novel Polyketide Pigments by Fusarium chlamydosporum

Aim: The aim of the present study was to evaluate the pigment production by the fungus Fusarium chlamydosporum in Glucose Peptone Yeast Extract medium and further to assess its toxicity by in vitro methods. Materials and Methods: The coloured crude extract yielded 4 fractions when subjected to column chromatography, upon which Fraction 2 and 4 were subjected to characterization procedures by UV-Visible spectrophotometry, Fourier Transform Infrared Spectroscopy and Molecular weight determination by Liquid Chromatography Mass Spectroscopy (LCMS). The toxicity of the pigments was evaluated in vitro on L-929 Mouse Fibroblast cell lines by MTT Assay. Results: The fungus produced dark red pigment in Glucose Peptone Yeast Extract medium on extraction with ice cold chloroform. The results summarized Fraction 2 and 4 to be the polyketide derivatives, Rubrofusarin and 8-O-methyl fusarubin respectively wherein the IC50 values of rubrofusarin and 8-O-methyl fusarubin was 183.85 and 82.366 μg/ml respectively. Conclusion: The significance of the present study lies in the characterization of 2 novel polyketides, rubrofusarin and 8-O-methyl fusarubin from F. chlamydosporum and there have been no literature reviews on the production of these pigments from the fungus.

Reclassification of Olsenella gallinarum as Thermophilibacter gallinarum comb. nov. and description of Thermophilibacter immobilis sp. nov., isolated from the mud in a fermentation cellar used for the production of Chinese Luzhou-flavour Baijiu.

A novel Gram-stain-positive, strictly anaerobic, elliptical, non-motile and non-flagellated bacterium, designed LZLJ-2T, was isolated from the mud in a fermentation cellar used for the production of Chinese Luzhou-flavour Baijiu. Growth occurred at 28-45 °C (optimum, 37 °C), at pH 6.0-7.0 (optimum, pH 6.0) and with concentrations of NaCl up to 2 % (w/v; optimum, 0 %). On the basis of 16S rRNA gene sequence similarity, strain LZLJ-2T belonged to the genus Thermophilibacter and was most closely related to Thermophilibacter mediterraneus Marseille-P3256T (similarity 96.9 %), Olsenella gallinarum ClaCZ62T (similarity 96.6 %) and Thermophilibacter provencensis Marseille-P2912T (similarity 96.4 %). In addition, strain LZLJ-2T had high similarity to the genus Olsenella, including Olsenella profusa DSM 13989T (similarity 94.9 %), Olsenella umbonata DSM 22620T (similarity 94.9 %), Olsenella uli ATCC 49627T (similarity 94.22 %), Tractidigestivibacter scatoligenes DSM 28304T (similarity 93.9 %) and Paratractidigestivibacter faecalis KCTC 15699T (similarity 93.25 %). Comparative genome analysis showed that orthoANI values between strain LZLJ-2T and Thermophilibacter mediterraneus Marseille-P3256T, Olsenella gallinarum ClaCZ62T, Thermophilibacter provencensis Marseille-P2912T, Olsenella profusa DSM 13989T, Olsenella umbonata DSM 22620T, Olsenella uli ATCC 49627T, Tractidigestivibacter scatoligenes DSM 28304T and Paratractidigestivibacter faecalis KCTC 15699T were 78.68, 78.99, 78.29, 73.40, 74.00, 74.30, 75.08 and 77.23 %, and the genome-to-genome distance values were respectively 22.3, 22.5, 22.4, 19.6, 20.5, 19.7, 20.5 and 21.5 %. The genomic DNA G+C content of strain LZLJ-2T was 65.21 mol%. The predominant cellular fatty acids (>10 %) of strain LZLJ-2T were C18 : 1 cis 9 (33.7 %), C14 : 0 (22.0 %) and C18 : 1 cis 9 DMA (13.5 %). d-Glucose, sucrose, mannose, maltose, lactose (weak), salicin, glycerol (weak), cellobiose and trehalose (weak) could be used by strain LZLJ-2T as sole carbon sources. Enzyme activity results showed positive reactions with valine arylamidase, leucine arylamidase, crystine arylamidase, acid phosphatase, alkaline phosphatase, esterase (C4) (weakly positive), naphthol-AS-BI-phosphohydrolase, α-glucosidase and β-glucosidase. The major end products of glucose fermentation were lactic acid and acetic acid. It produced skatole from indole acetic acid, and produced p-cresol from modified peptone-yeast extract medium with glucose. Based on the 16S rRNA gene trees as well as the genome core gene tree, it is suggested that Olsenella gallinarum are transferred to genus Thermophilibacter as Thermophilibacter gallinarum comb. nov. Based on phenotypic, genotypic and phylogenetic data, strain LZLJ-2T is considered to represent a novel species of the genus Thermophilibacter, for which the name Thermophilibacter immobilis sp. nov. is proposed. The type strain is LZLJ-2T (=KCTC 25162T=JCM 34224T).

Comparative Analysis of Different Nutrient Media for Growth of Agrobacterium tumefaciens under Small Volume Cultures

Aims: To assess the effects of different selective complex growth media: Yeast Extract Peptone (YEP), Yeast Extract Mannitol (YEM), and Luria Bertani (LB) on growth and multiplication of three different strains of Agrobacterium tumefaciens.
 Place and Duration of Study: Molecular Biology Laboratory, Genetics and Tree Improvement Division, Arid Forest Research Institute, Jodhpur, Rajasthan, India, between July and December 2020.
 Methodology: Three strains of Agrobacterium (EHA105, GV3101 and LBA4404) were inoculated to grow on three different complex nutrient media (YEP, YEM, LB) supplemented with respective antibiotics for a period of 30 hours. Optical Density (O.D) at 600 nm was measured at every 3-hour interval to analyze differential growth pattern.
 Results: Though all the three nutrient media supported the growth of bacteria, YEP medium supported the fast growth of all strains of bacteria, LB medium was a little less efficient but comparable to YEP media. However, YEM medium proved the least supportive for bacterial growth among the three media types.
 Conclusion: Agrobacterium is used for genetic transformation of plant species and crop improvement. knowledge of the growth pattern of bacteria is necessary for the effective infection of plant material. We have analyzed that three strains of Agrobacterium on three different complex media, among the three media YEP media was supporting fast growth. This study can help the researchers to gain knowledge of the growth pattern of Agrobacterium to be used in the genetic transformation of plant species accordingly.

Characterization of melanin and optimal conditions for pigment production by an endophytic fungus, Spissiomyces endophytica SDBR-CMU319.

Melanin is a natural pigment that is produced by filamentous fungi. In this study, the endophytic species, Spissiomyces endophytica (strain SDBR-CMU319), produced a brown-black pigment in the mycelia. Consequently, the pigment was extracted from the dried fungal biomass. This was followed by pigment purification, characterization and identification. Physical and chemical characteristics of the pigment showed acid precipitation, alkali solubilization, decolorization with oxidizing agents, and insolubility in most organic solvents and water. The pigment was confirmed as melanin based on ultraviolet-visible spectroscopy, Fourier-transform infrared, and electron paramagnetic resonance spectra analyses. The analyses of the elemental composition indicated that the pigment possessed a low percentage of nitrogen, and therefore, was not 3,4-dihydroxyphenylalanine melanin. Inhibition studies involving specific inhibitors, both tricyclazole and phthalide, and suggest that fungal melanin could be synthesized through the 1,8-dihydroxynaphthalene pathway. The optimum conditions for fungal pigment production from this species were investigated. The highest fungal pigment yield was observed in glucose yeast extract peptone medium at an initial pH value of 6.0 and at 25°C over three weeks of cultivation. This is the first report on the production and characterization of melanin obtained from the genus Spissiomyces.

De novo production of aromatic m-cresol in Saccharomyces cerevisiae mediated by heterologous polyketide synthases combined with a 6-methylsalicylic acid decarboxylase

As a flavor and platform chemical, m-cresol (3-methylphenol) is a valuable industrial compound that currently is mainly synthesized by chemical methods from fossil resources. In this study, we present the first biotechnological de novo production of m-cresol from sugar in complex yeast extract-peptone medium with the yeast Saccharomyces cerevisiae. A heterologous pathway based on the decarboxylation of the polyketide 6-methylsalicylic acid (6-MSA) was introduced into a CEN.PK yeast strain. For synthesis of 6-MSA, expression of different variants of 6-MSA synthases (MSASs) were compared. Overexpression of codon-optimized MSAS from Penicillium patulum together with activating phosphopantetheinyl transferase npgA from Aspergillus nidulans resulted in up to 367 mg/L 6-MSA production. Additional genomic integration of the genes had a strongly promoting effect and 6-MSA titers reached more than 2 g/L. Simultaneous expression of 6-MSA decarboxylase patG from A. clavatus led to the complete conversion of 6-MSA and production of up to 589 mg/L m-cresol. As addition of 450–750 mg/L m-cresol to yeast cultures nearly completely inhibited growth our data suggest that the toxicity of m-cresol might be the limiting factor for higher production titers.

Optimized xylose isomerase uptake and expression level in Saccharomyces cerevisiae for improving ethanol production

The ability to engineer the yeast Saccharomyces cerevisiae to efficiently convert lignocellulosic biomass to ethanol remains a considerable challenge. Here, we propose a new reprogrammable strategy to optimize the expression level of the xylose isomerase (XI) gene with the induction of mutations in S . cerevisiae to improve efficient ethanol production and productivity. We sought to fine-tune the xylose uptake and catabolism abilities of S. cerevisiae during fermentation by improving efficiency of the xylose transporter, which was fused with four copies of the XI gene under the control of different promoters to obtain recombinant yeast strains. In fermentation experiments, the optimized strain CW9 cultured in yeast extract-peptone (YP) medium containing approximately 65 g/L glucose and 55 g/L xylose produced consistent ethanol yields of 0.45 g/g total sugar in about 72 h, which was close to 90% of the theoretical yield. These promising results indicate that strain CW9 is the best producer of ethanol from mixed sugar when synthetically regulating the xylose assimilation pathway. Overall, this study provides an optimal method to control XI expression levels to find better conditions for enhancing biofuel production.

Clostridium pabulibutyricum sp. nov., a butyric-acid-producing organism isolated from high-moisture grass silage.

A Gram-stain-variable, strictly anaerobic, rod-shaped, catalase-negative and endospore-forming bacterial strain, designated MJC39T, was isolated from grass silage preserved in Hokkaido, Japan. Growth occurred at 20-42 °C, pH 5.0-7.0 and NaCl concentrations up to 2 % (w/v). The isolated strain MJC39T produced butyric acid in peptone yeast extract medium with glucose. The DNA G+C content of strain MJC39T was 34.4±0.2 mol%. The major cellular fatty acids (>10 %) were C14 : 0, C16 : 0 and summed feature 3 (including C16 : 1ω7c/C16 : 1ω6c). No respiratory quinones were detected. The polar lipids of strain MJC39T were phosphatidylglycerol, phosphatidylethanolamine, diphosphatidylglycerol, one unidentified lipid, one unidentified aminolipid, two unidentified glycolipids, one unidentified phospholipid, one unidentified aminoglycolipid and one unidentified phosphoaminoglycolipid. Phylogenetic analysis based on 16S rRNA gene sequences showed that strain MJC39T was a member of the genus Clostridium and is closely related to Clostridium tyrobutyricum JCM 11008T (95.8 % similarity) and Clostridium algifaecis MB9-7T (95.5 % similarity). Based on the genotypic, phenotypic and chemotaxonomic characteristics, strain MJC39T represents a novel species of the genus Clostridium, for which the name Clostridium pabulibutyricum sp. nov. is proposed. The type strain is MJC39T (=JCM 31506T=DSM 103944T).

Media development for large scale Agrobacterium tumefaciens culture.

A chemically defined media was developed for growing Agrobacterium tumefaciens at large scale for commercial production of recombinant proteins by transient expression in plants. Design of experiments was used to identify major and secondary effects of ten media components: sucrose, ammonium sulfate ((NH4 )2 SO4 ), magnesium sulfate heptahydrate (MgSO4 *7H2 O), calcium chloride dihydrate (CaCl2 *2H2 O), iron (II) sulfate heptahydrate (FeSO4 *7H2 O), manganese (II) sulfate monohydrate (MnSO4 *H2 O), zinc sulfate heptahydrate (ZnSO4 *7H2 O), sodium chloride (NaCl), potassium chloride (KCl) and a sodium/potassium phosphate buffer (Na2 HPO4 /KH2 PO4 ). Calcium and zinc were found to have no detectable impact on biomass concentration or transient expression level, and concentrations of the other components that maximized final biomass concentration were determined. The maximum specific growth rate of Agrobacterium strain C58C1 pTFS40 in this media was 0.33 ± 0.01 h-1 and the final biomass concentration after 26 h of batch growth in shake flasks was 2.6 g dry cell weight/L. Transient expression levels of the reporter protein GUS following infiltration of a recombinant Agrobacterium strain C58C1 into N. benthamiana were comparable when the strain was grown in the defined media, Lysogeny Broth (LB) media, or yeast extract-peptone (YEP) media. In LB and YEP media, free amino acid concentration was measured at three points over the course of batch growth of Agrobacterium strain C58C1 pTFS40; results indicated that l-serine and l-asparagine were depleted from the media first, followed by l-alanine and l-glutamic acid. © 2017 American Institute of Chemical Engineers Biotechnol. Prog., 33:1218-1225, 2017.

Growth kinetics and scale-up of Agrobacterium tumefaciens.

Production of recombinant proteins in plants through Agrobacterium-mediated transient expression is a promising method of producing human therapeutic proteins, vaccines, and commercial enzymes. This process has been shown to be viable at a large scale and involves growing large quantities of wild-type plants and infiltrating the leaf tissue with a suspension of Agrobacterium tumefaciens bearing the genes of interest. This study examined one of the steps in this process that had not yet been optimized: the scale-up of Agrobacterium production to sufficient volumes for large-scale plant infiltration. Production of Agrobacterium strain C58C1 pTFS40 was scaled up from shake flasks (50-100mL) to benchtop (5L) scale with three types of media: Lysogeny broth (LB), yeast extract peptone (YEP) media, and a sucrose-based defined media. The maximum specific growth rate (μ max) of the strain in the three types of media was 0.46±0.04h-1 in LB media, 0.43±0.03h-1 in YEP media, and 0.27±0.01h-1 in defined media. The maximum biomass concentration reached at this scale was 2.0±0.1, 2.8±0.1, and 2.6±0.1g dry cell weight (DCW)/L for the three media types. Production was successfully scaled up to a 100-L working volume reactor with YEP media, using k L a as the scale-up parameter.

Investigation on Saccharification and Bioethanol Production from Pretreated Agro-Residues Using a Mangrove Associated Actinobacterium Streptomyces variabilis (MAB3)

The present study was undertaken to evaluate the saccharification, followed by bioethanol production by an actinobacterium Streptomyces variabilis (MAB3) isolated from the sediment sample of mangrove environment using Modified Yeast extract—Peptone medium substituted with different concentrations of xylanase (50 to 400 IU) pretreated various agro-residues like vegetable, banana, mango, sugarcane bagasse and sugarcane juice through fermentation process. Among the tested residues, sugarcane juice substituted medium pretreated with 200.0 IU concentration of xylanase exhibited maximum level of reducing sugar (50.19 mg/g), degree of saccharification (59.49%) as well as bioethanol (4.69 g/L) production. Further the organism expressed highest saccharification yield and bioethanol production at the optimized cultural conditions of pH 6, temperature 30 °C, inoculum size 2.5% and incubation time 72 h substituted with 2.5% dextrose and 2.0% urea, respectively as carbon and nitrogen sources. The concentration of produced bioethanol (82.26%) from the optimized medium was determined through HPLC analysis. Finally the bioethanol was evaluated through FT-IR and GC-MS analysis. The basic functional ethanol groups (O–H and C–O) from the optimized medium were denoted in both FT-IR and GC-MS analysis at the wavenumber of 3272.22 and 1077.15 cm−1 with the retention time of 2.60 min, respectively. Based on the results, it could be confirmed that the selected isolate is a potent strain and it can able to hydrolyze the pretreated agro-residues and also it can able to convert the pretreated agro residues into economically important byproduct like bioethanol.

Characterization of the transcription factor encoding gene, KlADR1: metabolic role in Kluyveromyces lactis and expression in Saccharomyces cerevisiae

In Saccharomyces cerevisiae, Adr1 is a zinc-finger transcription factor involved in the transcriptional activation of ADH2. Deletion of KlADR1, its putative ortholog in Kluyveromyces lactis, led to reduced growth in glycerol, oleate and yeast extract-peptone medium suggesting, as in S. cerevisiae, its requirement for glycerol, fatty acid and nitrogen utilization. Moreover, growth comparison on yeast extract and peptone plates showed in K. lactis a KlAdr1-dependent growth trait not present in S. cerevisiae, indicating different metabolic roles of the two factors in their environmental niches. KlADR1 is required for growth under respiratory and fermentative conditions like KlADH, alcohol dehydrogenase genes necessary for metabolic adaptation during the growth transition. Using in-gel native alcohol dehydrogenase assay, we showed that this factor affected the Adh pattern by altering the balance between these activities. Since the activity most affected by KlAdr1 is KlAdh3, a deletion analysis of the KlADH3 promoter allowed the isolation of a DNA fragment through which KlAdr1 modulated its expression. The expression of the KlADR1-GFP gene allowed the intracellular localization of the factor in K. lactis and S. cerevisiae, suggesting in the two yeasts a common mechanism of KlAdr1 translocation under fermentative and respiratory conditions. Finally, the chimeric Kl/ScADR1 gene encoding the zinc-finger domains of KlAdr1 fused to the transactivating domains of the S. cerevisiae factor activated in Scadr1Δ the transcription of ADH2 in a ScAdr1-dependent fashion.

Biodegradation and decolorization of melanoidin solutions by manganese peroxidase yeasts.

The ability of selected manganese peroxidase (MnP) yeast strains, isolated from the mixed liquor of an activated sludge bioreactor treating melanoidins wastewater, was investigated in this work, aiming to examine the degradation potential of melanoidins, in the presence or absence of nutrients. Ten yeast strains were initially isolated from the mixed liquor; four yeast strains (Y1, Y2, Y3 and Y4) were selected for further studies, based on their tolerance towards synthetic melanoidins (SMs) degradation and MnP activity onto solid agar medium. The Y1 strain exhibited almost 98% homology to Candida glabrata yeast, based on 28S rRNA identification studies. During experiments carried out using SM at 30 °C, the four isolated yeast cultures showed a noticeable organic matter reduction and decolorization capacity reaching up to 70% within 2-5 days. However, the corresponding yeast cultures grown in glucose peptone yeast extract medium using real melanoidin wastewater at 30°C showed lower organic matter and color removal capacity, reaching about 60% within 2-5 days. Nevertheless, it was found that the removal of real and synthetic melanoidins could be carried out by these strains under non-aseptic conditions, without requiring further addition of nutrients.

Enhanced fibrinolytic protease production by Serratia marcescens RSPB11 through Plackett-Burman and response surface methodological approaches

A well characterized alkaline metalloprotease enzyme called serralysin with fibrinolytic activity has been reported in the newly isolated Serratia marcescens RSPB11. In view of its potential application in thrombolytic therapy this study has been made for understanding the nutritional parameters requirement needed for production. Therefore, medium components required for the production of serralysin were optimized using a two step statistical approach. Fermentation variables were selected in accordance with the Plackett-Burman design and were further optimized via response surface methodological approach. A total of seven parameters viz., casein, dextrose, KH2PO4, MgSO4, NaCl, CaCl2 and inoculum have been considered for the optimization studies. The statistical model was constructed via central composite design (CCD) using five screened variables (casein, dextrose, KH2PO4, CaCl2 and inoculum size). An overall 51.8% increase in protease production was achieved in the optimized medium as compared with the unoptimized casein medium.With the application of statistical design methodology serralysin production increased significantly with optimized casein medium (23910 U/ml) when compared to yeast extract-peptone medium (5363 U/ml).

Effects of Hydrogen Peroxide on Different Toxigenic and Atoxigenic Isolates of Aspergillus flavus.

Drought stress in the field has been shown to exacerbate aflatoxin contamination of maize and peanut. Drought and heat stress also produce reactive oxygen species (ROS) in plant tissues. Given the potential correlation between ROS and exacerbated aflatoxin production under drought and heat stress, the objectives of this study were to examine the effects of hydrogen peroxide (H2O2)-induced oxidative stress on the growth of different toxigenic (+) and atoxigenic (−) isolates of Aspergillus flavus and to test whether aflatoxin production affects the H2O2 concentrations that the isolates could survive. Ten isolates were tested: NRRL3357 (+), A9 (+), AF13 (+), Tox4 (+), A1 (−), K49 (−), K54A (−), AF36 (−), and Aflaguard (−); and one A. parasiticus isolate, NRRL2999 (+). These isolates were cultured under a H2O2 gradient ranging from 0 to 50 mM in two different media, aflatoxin-conducive yeast extract-sucrose (YES) and non-conducive yeast extract-peptone (YEP). Fungal growth was inhibited at a high H2O2 concentration, but specific isolates grew well at different H2O2 concentrations. Generally the toxigenic isolates tolerated higher concentrations than did atoxigenic isolates. Increasing H2O2 concentrations in the media resulted in elevated aflatoxin production in toxigenic isolates. In YEP media, the higher concentration of peptone (15%) partially inactivated the H2O2 in the media. In the 1% peptone media, YEP did not affect the H2O2 concentrations that the isolates could survive in comparison with YES media, without aflatoxin production. It is interesting to note that the commercial biocontrol isolates, AF36 (−), and Aflaguard (−), survived at higher levels of stress than other atoxigenic isolates, suggesting that this testing method could potentially be of use in the selection of biocontrol isolates. Further studies will be needed to investigate the mechanisms behind the variability among isolates with regard to their degree of oxidative stress tolerance and the role of aflatoxin production.

Evaluation of Two Modified Culture Media forLeishmania infantumCultivation Versus Different Culture Media

The aim of this study is to improve the cultivation of Leishmania promastigotes without the use of common, semisolid culture media such as Evans' modified Tobie's medium (EMTM), liquid RPMI 1640, and Peptone-yeast extract medium (P-Y). Although EMTM medium permits the growth of a high number of parasites, it is technically difficult to prepare as it requires the use of fresh rabbit blood from animals bred on farms, while RPMI 1640 and P-Y show lower growth rates than the EMTM. There is, therefore, a need to develop new blood-free and time-saving culture systems. The aim of this paper is to propose new modified microbiological media, named RPMI-PY and Tobie-PY, to isolate Leishmania and cultivate parasites for research and diagnostic purposes. This study compares classic culture media to the new media, RPMI-PY and Tobie-PY, and demonstrates that the new media have superior performance in terms of time and parasitic load. The growth rate of the parasite was significantly higher at 24, 48, and 72 hr cultivation, based on counts using Bürker's chambers, when compared to classic media. This study was carried out at the National References Centre for Leishmaniasis (C.Re.Na.L.) where the isolation procedures are conducted daily from a number of different biological matrices.

Rapid Synthesis of Silver Nanoparticles from Fusarium oxysporum by Optimizing Physicocultural Conditions

Synthesis of silver nanoparticles (SNPs) by fungi is emerging as an important branch of nanotechnology due to its ecofriendly, safe, and cost-effective nature. In order to increase the yield of biosynthesized SNPs of desired shape and size, it is necessary to control the cultural and physical parameters during the synthesis. We report optimum synthesis of SNPs on malt extract glucose yeast extract peptone (MGYP) medium at pH 9–11, 40–60°C, and 190.7 Lux and in sun light. The salt concentrations, volume of filtrate and biomass quantity were found to be directly proportional to the yield. The optimized conditions for the stable and rapid synthesis will help in large scale synthesis of monodispersed SNPs. The main aim of the present study was to optimize different media, temperature, pH, light intensity, salt concentration, volume of filtrate, and biomass quantity for the synthesis of SNPs by Fusarium oxysporum.

Production, Purification, and Biochemical Characterization of a Fibrinolytic Enzyme from Thermophilic Streptomyces sp. MCMB-379

Production of the fibrinolytic enzyme was carried out using 2.5-L glass fermentor, culture of thermophilic Streptomyces sp., and glucose yeast extract peptone medium of pH 8.0. Five successive batches were carried out under controlled fermentation conditions viz., agitation 140 rpm, aeration 0.5 vvm, 55 °C, and 18 h. The total protein extracellularly produced in the cell-free broth was ~300-500 mg/L. The enzyme belongs to serine endopeptidase type. Studies on the fibrin degradation indicate that the enzyme degrades the fibrin into small molecular weight products as seen from HPLC profile. Phase-contrast microscopic structure of fibrin showed that enzyme cleaves the fibrin filaments. The ex vivo activity of the actinokinase was compared with 500 IU of urokinase and 350 IU of streptokinase. The ex vivo clot lysis was found to be faster as compared to the commercial available enzymes.

Asymmetric Response of Carbon Metabolism at High and Low Salt Stress in Vibrio sp. DSM14379

Energy redistribution between growth and maintenance in salt-stressed cells is especially important for bacteria living in estuarine environments. In this study, Gram-negative bacterium Vibrio sp. DSM14379, isolated from the estuarine waters of the northern Adriatic Sea, was grown aerobically in a peptone-yeast extract medium with different salt concentrations (ranging from 0.3% to 10% (w/v) NaCl). Carbon flux through the central metabolic pathways was determined at low and high salt concentrations. At low salt concentrations, total endogenous respiration, dehydrogenase activity, and net intracellular adenosine triphosphate (ATP) concentration significantly increased, the phosphofructokinase and pyruvate kinase activity decreased, whereas glucose-6-phosphate dehydrogenase activity remained unchanged. The carrying capacity of bacterial culture decreased dramatically, indicating a severe metabolic imbalance at low salt concentrations. At high salt concentrations, carrying capacity decreased gradually. There was a large increase in glucose-6-phosphate dehydrogenase activity, which correlated with a 10-fold increase in concentration of osmoprotectant L-proline. There was no significant change of net intracellular ATP concentration, phosphofructokinase, or pyruvate kinase activity. The results indicate that Vibrio sp. DSM14379 central metabolic pathways respond to low and high salt concentrations asymmetrically; cells are better adapted to high salt concentrations. In addition, cells in the stationary phase can tolerate induced salt stress without a significant change in dehydrogenase activity or endogenous respiration for at least 1 h, but need to alter their macromolecular composition and carbon flux distribution for long-term survival.

Effect of Product Inhibition on Xylose Fermentation to Ethanol by Saccharomyces cerevisae 424A (LNH-ST)

Commercially viable manufacturing of cellulosic ethanol requires high titers of product from both hexose and pentose fermentation. This article reports inhibition of initial specific xylose consumption rates and ethanol generation in batch fermentations of xylose using S. cerevisiae 424A (LNH-ST), a genetically modified strain capable of co-fermenting glucose and xylose. The fermentations were carried out in yeast extract peptone (YEP) medium in the presence of varying concentrations of ethanol (0% to 9% w/v) either added in a single dose or generated in situ by the yeast from glucose prior to xylose fermentation. The Levenspiel inhibition function was used to model inhibition of initial specific xylose consumption rates by ethanol. When ethanol was added in a single dose, the yeast ceased xylose fermentation when ethanol concentration reached 90 g L-1. However, when ethanol was generated in situ from glucose, the maximum final titer of ethanol was 110 g L-1. Comparing the effect of ethanol on xylose fermentation to the effect of ethanol on HXT transport of xylose in non-xylose-fermenting yeast suggests that inhibition of xylose transport into the cell is rate-limiting for fermentation.