High Concentration Of Yeast Extract Research Articles

Exploring the extremes: applying high concentration of yeast extract leads to drastic morphological changes and elimination of (+)-geodin and asterric acid production in Aspergillus terreus submerged cultures

ObjectiveEvaluation of morphology and secondary metabolites production in Aspergillus terreus ATCC 20542 cultures over a wide range of lactose and yeast extract concentrations from 0.2 up to an extremely high level of 200 g l−l.ResultsThe morphological differences of mycelial objects were quantified with the use of morphological parameters calculated by applying the tools of digital image analysis. At 200 g l−l of yeast extract clumps and loose hyphae were recorded instead of pellets commonly observed in submerged cultures of A. terreus. Under these conditions the biosynthesis of (+)-geodin and asterric acid was totally blocked, lovastatin formation was found to be at a relatively low level and biomass production turned out to be greater than in the remaining variants, where the pelleted growth was observed. At 200 g l−l of lactose the production of lovastatin, (+)-geodin and asterric acid was visibly stimulated compared to the media containing 0.2, 2 and 20 g l−l of the sugar substrate, but at the same time no traces of butyrolactone I could be detected in the broth. Lactose at the extremely high concentration of 200 g l−l did not induce the drastic morphological changes observed in the case of 200 g l-1 of yeast extract. It was proved that at the C/N values as low as 4 and as high as 374 A. terreus not only continued to display growth but also exhibited the production of secondary metabolites. The use of cultivation media representing the equivalent C/N ratios led to different metabolic and morphological outcomes depending on the concentration of lactose and yeast extract that contributed to the given C/N value.ConclusionThe extremely high concentration of yeast extract leads to marked morphological changes of A. terreus and the elimination of (+)-geodin and asterric production, while applying the excess of lactose is stimulatory in terms of lovastatin production.

Study on the mycelium growth and primordial formation of king oyster mushroom (Pleurotus eryngii) on cardboard and spent coffee ground

Cultivation of edible mushrooms on urban wastes represents one of the most economically and cost-effective organic recycling processes. An effective tool to identify necessary nutrients for the production of fruiting bodies on the specialty substrates is mycelium growth. Hence, mycelium of king oyster mushroom (Pleurotus eryngii) were experimentally evaluated on cardboard and spent coffee ground (SCG) substrates for the mycelial growth rate, density and primordial formation. Studies were carried out using five different substrate formulations viz., 100% cardboard (TS1), 100% SCG (TS2), 50% cardboard+50% SCG (TS3), 70% cardboard+30% SCG (TS4) and 30% cardboard+70% SCG (TS5). The efficiency of different yeast extract concentrations (i.e. 1, 5, 10, 20, 30 and 50 g/l) as a supplement in potato dextrose agar media (PDA) on P. eryngii growth was also determined. The concentration of 1 g/l of yeast extract showed the best effects on mycelial growth and primordia formation of P. eryngii, while high concentration of yeast extract (550 g/l) did not show any beneficial influence. Combination between cardboard and SCG, especially substrate formulations of 30% cardboard+70% SCG increased mycelial density and number of primordial formations of P. eryngii compared to the substrates of cardboard or SCG alone. The results revealed a potential opportunity for commercial cultivation of edible mushrooms, especially P. eryngii for utilization of different recyclable residues as well as urban generated wastes reduction.

Increased torulene production by the red yeast, Sporidiobolus pararoseus, using citrus juice

Response surface methodology was applied to maximize the yield and production of carotenoids by Sporidiobolus pararoseus WZ012 using citrus juice. A high concentration of yeast extract and citrus juice favored carotenoid production and biomass concentration, respectively. Under optimal conditions, a more than 51 percent (from 860 to 1300 µg/g) and 62 percent (from 17.05 to 27.66 mg/L) respective enhancement in intracellular and total carotenoid production was achieved. Finally, this process was successfully upscaled in a 5-L fermentor. A comparison of the carotenoid distributions revealed that torulene (61.3%) was the dominant carotenoid when using the citrus based medium, while the main carotenoid was β-carotene (62.5%) when using the glucose medium. The present work provides an alternative method to produce high-value products derived from waste and low-grade citrus.

Lithoautotrophical oxidation of elemental sulfur by fungi including Fusarium solani isolated from sandstone Angkor temples

Previous study about Fusarium solani THIF01, isolated from deteriorated sandstones of Angkor Wat, Cambodia, has suggested that this fungal strain harbored an endobacterium Bradyrhizobium sp. and oxidized elemental sulfur (S0) in carbon-free media. Here we eliminated the endobacterium in THIF01 and confirmed that the cured THIF01 retained the ability of chemolithoautotrophic growth on S0. In addition, thirteen out of eighteen identified fungal strains formed clearing zone on the agarose-solidified basal salts medium containing S0. F. solani f.sp. pisi NBRC9425 grew in carbon-free liquid medium oxidizing S0 to thiosulfate and sulfate. Furthermore, we proved that various fungi were capable of growth chemolithotrophically on S0. An addition of up to 15 mg l−1 of yeast extract to mineral-salts medium containing S0 enhanced the production of thiosulfate and sulfate, and higher concentration of yeast extract shifted the metabolism from chemolithotroph to chemoorganotroph. Fungal hyphae were observed to attach to the S0 granules when growing with less than 100 mg l−1 yeast extract in the medium, but no such association was evident when incubated with 200 mg l−1 or more yeast extract. Glucose at concentrations of up to 1 mg l−1 did not show any negative effect on the sulfur oxidation, indicating there was a threshold concentration of organic compounds affecting the chemolithotrophic growth that has been observed before in the chemolithoautotrophic and chemolithomixotrophic sulfur oxidizing bacteria.

Different types of H2 photoproduction by starch-utilizing co-cultures of Clostridium butyricum and Rhodobacter sphaeroides

Co-culture of Clostridium butyricum and Rhodobacter sphaeroides displayed different types of H2 photoproduction from starch: quick low-yield (2.6 mol/mol glucose), prolonged high-yield (6.1 mol/mol glucose) and delayed low-yield (4.2 mol/mol glucose). It depended primarily on the ratio of two species and, besides, some other factors. The first type H2 photoproduction was similar to that in Clostridium, observed at high clostridia/purple bacteria ratio and promoted by low light intensity, temperature above and below optimum, reduced conditions, low initial pH or buffer concentration, high concentration of yeast extract (320 mg/L). The second type, high yield H2 production, was favored by low clostridia/purple bacteria ratio, high light intensity, and high concentration of yeast extract (320 mg/L). The third type, delayed H2 photoproduction, was observed at the lowest clostridia/purple bacteria ratio and was promoted by low concentration of yeast extract (25 mg/L). Thus, a well-known crucial effect of a species ratio on H2 photoproduction was in turn controlled by other factors, especially yeast extract concentration.

English

This paper reported the effect of yeast extract and chitosan with combination of yeast extract on the growth and morphological changes and production of phenolics in the in vitro plantlets of Curcuma mangga . Yeast extract did not show any effect on the biomass and shoot proliferation of in vitro plantlets. However, the plantlets showed morphological abnormality when exposed to higher concentration of yeast extract (3.5 mgL -1 and above) supplemented into the culture medium. Plantlets cultured in media supplemented with 3.5 and 5.0 mgL -1 of yeast extract showed higher radical scavenging activity (RSA) which also indicated that stress induced by yeast extract might elicit the production of secondary metabolites which acted as free radical scavenger in 1,1-diphenyl-2- picrylhydrazyl (DPPH) assay. The plantlets treated with different concentration of chitosan combined with 3.5 mgL -1 of yeast extract affected the biomass of C. mangga . The plantlets that were cultured in media supplemented with 150 mgL -1 of chitosan combined and 3.5 mgL -1 of yeast extract showed higher RSA towards DPPH as compared to the other treatments. Kinetic of DPPH free RSA from C. mangga extract was considered slow as compared to quercetin and the correlation between total phenolic content and RSA was poor (R 2 = 0.2293) for yeast extract and (R 2 = 0.0373) for chitosan combination with yeast extract. This indicated that the presence of phenolic compounds in the extracts were not the major factor contributing to the anti-oxidative activity of C. mangga. Key words: Curcuma mangga, in-vitro, elicitor, phenolics, anti-oxidative activities.

Optimization of carotenoids by Rhodotorula glutinis

Response surface methodology was applied to maximize the yield and productivity of carotenoids by Rhodotorula glutinis strain 1151 using supplemented tomato waste based medium. Higher concentration of tomato waste extract and yeast extract favored the production of carotenoids. In contrast to carotenogenesis higher concentration of yeast extract negatively affected the formation of biomass whereas higher amount of glucose in the medium favored biomass indicating that carotenogenesis is not correlated to biomass. The optimal concentration of medium components for maximum total carotenoids and corresponding biomass production as obtained from model were calculated to be as 660 mL/L, 1.5, 4.5, 7.4, and 10 g/L for tomato extract, malt extract, yeast extract, peptone, and glucose, respectively.

Influence of medium components and fermentation conditions on the production of bacteriocin(s) by Bacillus licheniformis AnBa9

Recently, antibacterial peptides are gaining more attention as an alternative therapeutics and food and other products from spoilage and deterioration. Antibacterial peptide producing strains were isolated from sediments of slaughterhouse sewage wastes. One among them, identified as Bacillus licheniformis inhibited the growth of several gram positive bacteria. Response surface methodology with central composite rotary design was used for optimization of fermentation medium and conditions for antibacterial peptide production. Lactose, NH 4NO 3, yeast extract and NaCl and environmental factors such as pH, temperature and incubation period were selected as variables. Among ingredients, high concentration of yeast extract and NaCl had a positive effect on antibacterial peptide production and specific activity, respectively. Alkaline pH and high temperature favoured the production of antibacterial peptide by B. licheniformis AnBa9. Under optimized condition, B. licheniformis AnBa9 produced 25-fold higher production of antibacterial peptide than the un-optimized condition. Biochemical characteristics of the antibacterial peptides of B. licheniformis AnBa9 revealed that they are of bacteriocin type.

Isolation and characterization of acidophilic heterotrophic iron-oxidizing bacterium from enrichment culture obtained from acid mine drainage treatment plant

An acidophilic heterotrophic bacterium, designated as HIB4, having the ability to oxidize ferrous ion was newly isolated from a sample of an enrichment culture for iron-oxidizing bacteria, using the modified washed agarose/yeast extract (WAYE) medium with ferrous sulphate. The isolate HIB4 was an acidophilic, heterotrophic, mesophilic and gram-positive bacterium. Phylogenetically, it was classified under the genus Alicyclobacillus and was the closest to Alicyclobacillus disulfidooxidans SD-11 with 99.7% 16S rDNA homology. It grew and oxidized ferrous ion in the medium containing 0.02% (w/v) yeast extract. Yeast extract was an essential substrate for this bacterium because it could not grow or oxidize ferrous ion without yeast extract. However, a higher concentration of yeast extract inhibited the growth of HIB4, so that the optimum concentration of yeast extract for this bacterium to grow was 0.02% (w/v) at 0.08 mol/l of ferrous ion. On the other hand, ferrous ion oxidation occurred almost at the end of the bacterium's logarithmic growth phase and the isolate was able to grow without ferrous ion. These results denote that HIB4 did not obtain any energy from the ferrous ion oxidation and that HIB4 is an obligate heterotrophic and aerobic bacterium even though it oxidized ferrous ion. Also, HIB4 could not utilize any organic compounds, among the several organic chemicals used in this study, as a carbon source except yeast extract. These characteristics were completely different from these of A. disulfidooxidans SD-11 so that HIB4 might be a different species.

Accumulation of Ectoine in the Halotolerant Brevibacterium sp. JCM 6894.

The optimum conditions for the intracellular synthesis of the cyclic amino acid ectoine (1,4,5,6-tetrahydro-2-methyl-4-pyridine carboxylic acid) were determined using the halotolerant Brevibacterium sp. JCM 6894. The amount of ectoine synthesized in cells was quantitatively determined after extraction from cells grown under various conditions, such as different external osmolarities, incubation times, and types and concentrations of nutrients in the medium. The optimum condition for the synthesis of ectoine was confirmed to be consecutive cell transfers accompanied with the changes in the medium osmolarity as follows; cells grown in the presence of 0.3 M NaCl were transferred to medium containing 1.5-2 M NaCl. After incubation for 18-24 h a second transfer of the cells to fresh medium containing 2-3 M NaCl was carried out and the cells were incubated for a further 12-24 h. The addition of 50-100 mM glucose or a high concentration of yeast extract in the medium resulted in an increase in the intracellular concentration of ectoine as well as of the cell yield. The growth medium affording the highest ectoine productivity of strain JCM 6894 consisted not only of 2 M NaCl but also Polypepton (10.0 g/l), yeast extract (5.0 g/l), and glucose (9.0 g/l) as nutrients. The highest yield of ectoine, 800 mg/l culture, was obtained using the optimum medium and one osmotic upshock. This yield corresponded to about an 8-fold increase compared to that obtained using standard medium (2 M NaCl) without an osmotic shift. In addition, the ectoine which was synthesized in cells grown at high osmolarity was released well from the cells by osmotic downshock.

Accumulation of ectoine in the halotolerant Brevibacterium sp. JCM 6894

The optimum conditions for the intracellular synthesis of the cyclic amino acid ectoine (1,4,5,6-tetrahydro-2-methyl-4-pyridine carboxylic acid) were determined using the halotolerant Brevibacterium sp. JCM 6894. The amount of ectoine synthesized in cells was quantitatively determined after extraction from cells grown under various conditions, such as different external osmolarities, incubation times, and types and concentrations of nutrients in the medium. The optimum condition for the synthesis of ectoine was confirmed to be consecutive cell transfers accompanied with the changes in the medium osmolarity as follows; cells grown in the presence of 0.3 M NaCl were transferred to medium containing 1.5–2 M NaCl. After incubation for 18–24 h a second transfer of the cells to fresh medium containing 2–3 M NaCl was carried out and the cells were incubated for a further 12–24 h. The addition of 50–100 mM glucose or a high concentration of yeast extract in the medium resulted in an increase in the intracellular concentration of ectoine as well as of the cell yield. The growth medium affording the highest ectoine productivity of strain JCM 6894 consisted not only of 2 M NaCl but also Polypepton (10.0 g/ l), yeast extract (5.0 g/ l), and glucose (9.0 g/ l) as nutrients. The highest yield of ectoine, 800 mg/ l culture, was obtained using the optimum medium and one osmotic upshock. This yield corresponded to about an 8-fold increase compared to that obtained using standard medium (2 M NaCl) without an osmotic shift. In addition, the ectoine which was synthesized in cells grown at high osmolarity was released well from the cells by osmotic downshock.

Influence of Zn2+ and Fe3+ on polysaccharide production and mycelium/yeast dimorphism of Aureobasidium pullulans in batch cultivations

Cultivation of Aureobasidium pullulans in medium with a low concentration of yeast extract (0.4 g/l) led to a decrease in the growth rate early in the fermentation as compared to cultivations in medium with high concentration of yeast extract. When this medium was supplemented with zinc and iron the cultivation closely resembled that obtained in medium with high concentration of yeast extract (4.0 g/l). The culture retained a high growth rate throughout the fermentation and the initiation of the mycelial to yeast (M-Y) transition and the exopolysaccharide production was delayed. In a defined medium or in defined medium without iron only a little exopolysaccharide was produced and the yeast fraction of the total biomass at the onset of the stationary phase was 22%–25%. However, cultivation in the defined medium without zinc resulted in a high production of exopolysaccharide and an increased intensity of the M-Y transition, which led to a yeast fraction of 41%.

Reduction of Yeast Extract Supplementation in Lactic Acid Fermentation of Whey Permeate by Immobllized Cell Technology

A stable 91-d continuous fermentation of whey permeate, supplemented with various concentrations of yeast extract (0 to 10 g·L–1), was carried out in a two-stage bioreactor for lactic acid production. The first fermentation stage contained Lactobacillus helveticus cells entrapped in κ-carrageenan and locust bean gum gel beads. The second free cell fermentation stage in series was continuously inoculated by cells released from the first stage. At a high concentration of yeast extract (10 g·L–1). maximum productivity was 41.3 g·L–1 per h for the first stage immobilized cell bioreactor containing 54% (vol/vol) gel beads, but the residual sugar concentration was unacceptably high (19.1 g·L–1). For the two-stage system, a total productivity of 13.5 g·L–1 per h could be obtained with 1 g·L–1 of residual sugars. An uncoupling effect between lactic acid and biomass production was observed at low yeast extract supplementation (0 to 1 g·L–1). Simulation analysis of the performance of a two-stage immobilized cell system operating at 1 g·L–1 residual sugar showed maximum productivities of 9.3 and 23.0 g·L–1 per h with 33 and 54% gel beads, respectively, and 10 g·L–1 yeast extract.

Clostridium tetanomorphum sp. nov., nom. rev.

A total of 46 glutamate-degrading strains of the genus Clostridium, including 36 new isolates, were examined for deoxyribonucleic acid (DNA)-DNA homology, protein patterns produced by polyacrylamide gel electrophoresis, and physiological characteristics in order to determine the differences between cochlearium and Clostridium tetanomorphum. Thirty-four newly isolated strains could be assigned to the group; two strains were classified as nontoxigenic tetani strains. The levels of DNA-DNA homology between C. cochlearium and were only 10 to 19%, and the protein patterns showed that there were great differences between both groups and other glutamate-degrading species. Biochemical tests supported these results. In contrast to C. cochlearium, all strains fermented carbohydrates (at least glucose and maltose); they also produced lipase and degraded ethanolamine. Moreover, C. cochlearium, like other glutamate-degrading species, needed a higher concentration of yeast extract than when it was grown on glutamate. On the basis of our results we propose C. tetanomorphum sp. nov., nom. rev. The type strain is strain NCTC 543 (= DSM 4474).