A Temperature-Shift Strategy in Batch Monascus Yellow Pigments Fermentation

According to the results of the single temperature on Monascus anka mutant growth and monascus yellow pigments production in this paper, two stages in the fermentation temperature control strategy has been operated as following: the temperature was 34°C to improve the Monascus growth before culture 48 hour and then 32°C was carried out to improve theItalic text yellow pigments production. The results demonstrated that two stages temperature control at 96 hours, the yield of monascus yellow pigments can arrive 164.51 OD units, it was 180.35%, 2165.48%, 107.66%, 5.76%, 33.23%, 36.74% higher than that of 26°C, 28°C, 30°C, 32°C, 34°C, 36°C fermentation, respectively. The maximum specific growth rate(µ) and the maximum specific production rate of yellow pigments( qy) could arrive 0.0528 h-1 and 0.404 OD.g-1.h-1, and it was 5.30% and 3.22% higher than that of 34°C and 32°C, respectively. The specific production rate of yellow pigments was varied from 0.2 OD.g-1.h-1 to 0.4 OD.g-1.h-1 in whole fermentation. Two stage temperature control strategy could improve the yellow pigments production, increase µ and and short the culture time.

Effects of pH and Aeration on the Production of Docosahexaenoic Acid by Thraustochytrium aureum in Controlled Batch Fermentor Cultures

Docosahexaenoic acid (DHA. C22:6 ω-3) is an important structural component of neural and retinal tissues .The DHA yield was highest at pH5.5. Glucose and maltose utilization were similar as a function of pH, linseed oil consumption increased at pH 5.5, indicating that the formation of DHA from linseed oil at pH5.5 was of increased importance. Increased aeration resulted in doubling of T. aureum cell dry weights, increasing DHA yields and increasing in the maximum DHA -specific production rate .

Isolation and Characterization ofShigella flexneriG3, Capable of Effective Cellulosic Saccharification under Mesophilic Conditions

ABSTRACTA novelShigellastrain (Shigella flexneriG3) showing high cellulolytic activity under mesophilic, anaerobic conditions was isolated and characterized. The bacterium is Gram negative, short rod shaped, and nonmotile and displays effective production of glucose, cellobiose, and other oligosaccharides from cellulose (Avicel PH-101) under optimal conditions (40°C and pH 6.5). Approximately 75% of the cellulose was hydrolyzed in modified ATCC 1191 medium containing 0.3% cellulose, and the oligosaccharide production yield and specific production rate reached 375 mg g Avicel−1and 6.25 mg g Avicel−1h−1, respectively, after a 60-hour incubation. To our knowledge, this represents the highest oligosaccharide yield and specific rate from cellulose for mesophilic bacterial monocultures reported so far. The results demonstrate thatS. flexneriG3 is capable of rapid conversion of cellulose to oligosaccharides, with potential biofuel applications under mesophilic conditions.

Photosynthetic carbon metabolism of size-fractionated phytoplankton during an experimental bloom in marine microcosms

Water samples, taken from station El in the English Channel, were incubated in 12–1 bottles and monitored for nine days. The distribution pattern of photosynthetically incorporated 14C was followed in three different size-fractions (0·2–2 μm, 2–10 μm and >10 μm) during the development of a bloom.A rapid increase in chlorophyll was observed just after enclosure, the highest values being reached by day 5, when a mixed community of diatoms and small flagellates formed the bulk of phytoplankton biomass. As the bloom developed, nutrients were depleted and, consequently, a decay of the phytoplankton populations occurred. Growth rates, estimated as chlorophyll-specific production rate, were higher for the largest size-fraction (0·53 d−1) than for the intermediate and smallest ones (0·32 d−1 for both).Throughout the bloom, the proportions of 14C incorporated into protein and low molecular weight metabolites (LMWM) were small, whereas the synthesis of storage products appeared to be enhanced. Carbon fixed into protein was higher during the exponential growth phase in all size-fractions, and incorporation into LMWM increased sharply when the bloom declined. Storage product synthesis varied between size-fractions.A close relationship was observed between growth rates, estimated as chlorophyll-specific production rate, and the protein/metabolite synthesis ratio (r2=0·90; n=24). These results suggest that, within the range of environmental variation we studied, this ratio would be a good estimator of growth rate for field studies.