Yeast Extract

Cellulose nanofibers with a size range of 5–100 nm have the potential to be a low cost renewable material that has application in a range of products. However, current chemical methods to produce crystalline nanofibers suffer from low yields and high chemical costs, while mechanical methods require high energy costs. Methods to lower the energy costs of the mechanical methods have not been well documented in the literature. A bleached softwood kraft pulp was processed using a mechanical dispersion mill and a homogenizer to produce cellulose nanofibers. Two different commercial enzymes were used to pretreat the wood fibers before the mechanical treatments. The resulting nanofibers were characterized by light microscopy, atomic force microscopy, and inverse gas chromatography. Results indicate that the dispersion mill does not affect the overall pulp fiber fibrillation, but does help prepare the sample for the homogenizer. Most fibrillation occurs after three passes through the homogenizer. The enzyme pretreatment has little effect on the size of the fibers, but does allow for higher solids to pass through the homogenizer without clogging. The dispersion component of surface energy of the resulting nanofibrils is impacted by the type of enzyme used. The measurement of acid–base properties proved to be challenging using current IGC experimental protocols.

Summary. In this study, calli were obtained from in vitro grown potato stem or leaf segments cv. Cosima on MS medium containing 2,4-D, NAA, kinetin and yeast extract. After three subcultures, well grown calli were exposed to UV-C radiation with approximately 6.24 µmol photon/m2/s for 30 min three times at an interval of 2 weeks. Somaclonal variation induced by UV-C

The objective of this work was to study the effect of initial pH and carbon and nitrogen content, supplied as glucose and malt extract (ME) respectively, on the production and composition of exopolysaccharides (EPS) produced by the medicinal fungus Ganoderma lucidum (Curtis) P. Karst in submerged culture. The experiment was carried out in flasks with 100 mL of the medium during 15 days at 28 ºC in an orbital shaker at 150 rev min-1. A central composite design with a minimal number of 20 runs was used [1]. All three studied factor were found to influence significantly the EPS production (and mycelial biomass). The maximum EPS production (594.3 mg L-1) was obtained for initial pH of 5.84 and initial contents of 33.6 and 4.48 g L-1 of glucose and ME respectively. Higher initial pH (6.68), glucose (40.95 g L-1) and ME (5.58 g L) contents on the culture medium lead to an increase of mycelial biomass but to a decrease in EPS, and consequently to a decrease in the production efficiency. Th...

Orange waste resulting from juice processing that contains a high level of fermentescible sugars was utilized as a basal medium at 2% (w/v) for the production of α-amylase (E.C.3.2.1.1) using a fungal strain of Aspergillus oryzae (Ahlburg) Cohen 1042.72, at 30 °C on a rotary shaker. The production of the α-amylase, proteins and biomass was achieved using the statistical method

WhenMortierella alpina ATCC 32222 was incubated in a glucose salts medium at 25°C the biomass (17.5 g/l) contained 9.62% arachidonic acid which amounted to 54% (w/w) of total biomass lipids. When the glucose concentration in the medium was varied from 0 to 150 g/l, the percentage of arachidonic acid in biomass and in lipids was highest at a glucose concentration of 30 g/l, but highest yield of arachidonic acid per litre of culture broth was observed at a glucose concentration of 100 g/l. While production of biomass reached a plateau of 17 g/l after a 3-day incubation at 25°C, the percentage of arachidonic acid in lipids and biomass increased dramatically from 3 to 6 days with a concurrent arachidonic acid yield increase from 0.89 to 1.63 g/l. Optimum initial culture pH for arachidonic acid production was in the range 6.0–6.7. By increasing the concentration of the glucose salts medium three-fold, yields of biomass and arachidonic acid were increased to 35.8 g/l and 3.73 g/l, respectively.

A multiplex real-time PCR assay for detection of Legionella pneumophila and Legionella spp. and including an internal control was designed. Legionella species, L. pneumophila, and the internal control were detected simultaneously by probes labeled with 6-carboxy-fluorescein, hexachlorofluorescein, and indodicarbocyanine, respectively. Therefore, no postamplification analysis was required in order to distinguish the targets. The sensitivity of both assays was 2.5 CFU/ml,

Cheese whey ultrafiltrate (WU) was used as the carbon source for the production of lactic acid by batch fermentation with Lactobacillus helveticus strain milano. The fermentation was conducted in a 400 ml fermentor at an agitation rate of 200 rpm and under conditions of controlled temperature (42° C) and pH. In the whey ultrafiltrate-corn steep liquor (WU-CSL) medium, the optimal

Ten selective mycological media were evaluated for their suitability to enumerate yeasts in six different dairy products. Although variability was observed in counts obtained for individual dairy products, no significant overall differences (p > 0.05) were observed among the 10 selective plating media. Antibiotic-supplemented media such as oxytetracycline glucose yeast agar (OGY), yeast extract glucose chloramphenicol agar (YGC), rose bengal chloramphenicol agar (RBCA) and rose bengal chlortetracycline agar (RBC) are superior to acidified potato dextrose agar and other acidified media for yeast enumeration in dairy products with neutral pH values. No significant differences (p > 0.05) among the 10 selective media ability to enumerate yeasts in dairy products at low pH values were observed.

Compost tea is gaining importance as an alternative to chemical fertilizers and pesticides. The microbial population in the compost tea contributes toward its effectiveness. An attempt was made to enhance the biological activity of compost tea by fortification with microbial substrates. Humic acid and yeast extract (4:7 w/w 100 g-1 compost) when used as microbial starter during brewing of compost tea significantly (P less than or equal to 0.05) enhanced the microbial population. There was a ten to hundred fold percentage increase for total bacteria, fungi and actinomycetes compared to control. The stability of microbial enriched compost tea was maintained up to four months of storage based on significantly higher number of viable cell counts when compared to compost tea without substrates (control). The viable microbial cell counts over a storage period of six months was 8.5x10(9), 4.6x10(6), 3.5x10(4), 3.9x10(4), 1.4x10(5), 4.8x10(4) and 7.3x10(5) for other bacteria.

Tobramycin was found to be less inhibitory to Flavobacterium columnare (formerly Flexibacter columnaris) than to other fish-associated bacteria. The selective capacity of Shieh medium, an isolation medium described for this species, was markedly enhanced by adding tobramycin at a concentration of 1 microgram/ml.

Production of lactic acid from beet molasses by Lactobacillus delbrueckii NCIMB 8130 in static and shake flask fermentation was investigated. Shake flasks proved to be a better fermentation system for this purpose. Substitution of yeast extract with other low cost protein sources did not improve lactic acid production. The maximum lactic acid concentration was achieved without treatment of molasses. A Central Composite Design was employed to determine the maximum lactic acid concentration at optimum values for the process variables (sucrose, yeast extract, CaCO3). A satisfactory fit of the model was realized. Lactic acid production was significantly affected both by sucrose–yeast extract and sucrose–CaCO3 interactions, as well as by the negative quadratic effects of these variables. Sucrose and yeast extract had a linear effect on lactic acid production while the CaCO3 had no significant linear effect. The maximum lactic acid concentration (88.0 g/l) was obtained at concentrations for sucrose, yeast extract and CaCO3 of 89.93, 45.71 and 59.95 g/l, respectively.