Y. D. Hang

Direct fermentation of corn to L(+)-lactic acid by Rhizopus oryzae

SummaryRhizopus oryzae NRRL 395 was found capable of fermenting ground corn directly to L(+)-lactic acid in the presence of calcium carbonate. The average yield of L(+)-lactic acid was more than 44% on the basis of the amount of total carbohydrate as glucose consumed.

Kinetics of direct fermentation of agricultural commodities to L(+)-lactic acid by Rhizopus oryzae

SummaryThe kinetics of fermenting barley, cassava, corn, oats, and rice directly to L(+) lactic acid byRhizopus oryzae NRRL 395 were determined. The rates of carbohydrate consumption and L(+) lactic acid production were found to be influenced by the type of substrate, the substrate concentration, the fermentation temperature, and the presence of a neutralizing agent.

Apple pomace: A potential substrate for citric acid production by Aspergillus niger

SummaryApple pomace was used as a fsubstrate for citric acid production by five strains of Aspergillus niger. A. niger NRRL 567 produced the greatest amount of citric acid from apple pomace in the presence of 4% methanol. The yield was 88% based on the amount of sugar consumed.

Apple pomace as substrate for microbial production of citric acid

SummaryGrape pomace was used as substrate for microbial production of citric acid. Of the five cultures examined,Aspergillusniger NRRL 567 was found to produce the greatest amount of citric acid from grape pomace in the presence of methanol at a concentration of 3% (vol/wt). The yield was 60% based on the amount of fermentable sugar consumed.

Production of L(+)-lactic acid byRhizopus oryzae immobilized in calcium alginate gels

Lactic acid is produced commercially by the fermentation of carbohydrates with homofermentative lactic acid bacteria (Prescott and Dunn, 1959). Lockwood et al (1936) reported that selected strains ofRhizopus oryzae in surface culture converted glucose to a large amount of L(+)-lactic acid in the presence of calcium carbonate, and Prescott and Dunn (1959) reviewed the production of L(+)-lactic acid by molds.

Solid-state fermentation of grape pomace for ethanol production

SummaryGrape pomace was used as a substrate for the production of ethanol under solid-state fermentation conditions. The yield of ethanol amounted to greater than 80% of the theoretical, based on the fermentable sugar consumed.

Purification and characterization of a glucoamylase from Rhizopus oryzae

Glucoamylase (EC 3.2.1.3) of Rhizopus oryzae NRRL 395 was purified approximately sevenfold by sequential ammonium sulfate fractionation, Biogel P-100 gel filtration, Q-Sepharose anion exchange and S-Sepharose cation exchange. The pH and temperature optima were 4·8 and 60°C, respectively. Enzyme was stable at temperatures up to 40°C and pH values between 3 and 8. The molecular weight was 67 000 daltons as determined by sodium dodecylsulfate-polyacrylamide gel electrophoresis, and the pI was 8·7 as determined by chromatofocusing. The Km for amylopectin and soluble starch were 0·98 and 1·34 mg/ml, respectively. The Vmax for amylopectin and soluble starch were 782 and 136 μmoles of glucose produced per mg of protein per min, respectively. The enzyme activity was inhibited by Hg2+, Pb2+ and Cd2+, but not by EDTA.

Chitosan production fromRhizopus oryzae mycelia

SummaryChitosan was successfully produced as a second valuable product fromRhizopus oryzae mycelia which had been previously used to make L(+) lactic acid. The highest yield of extractable chitosan was 700 mg/L.

Enzymatic synthesis of esters in organic medium with lipase from Byssochlamys fulva

Enzymatic esterification of sugars and fatty acids in tertiary butyl alcohol with lipase from Byssochlamys fulva NTG 9 was studied. Of different fatty acids examined, linoleic acid yielded the highest percentage of esterification of sugar (65.5%). Fructose gave a much higher percentage of esterification of fatty acid (71.3%) than glucose (47.8%), lactose (0%), maltose (67%) and sucrose (36.6%).

Effect of substrate moisture content on fungal production of citric acid in a solid state fermentation system

SummaryUnder solid state fermentation conditions, the production of citric acid byAspergillusniger varied considerably with the initial moisture content of apple pomace. The stimulating effect of methanol on fungal production of citric acid decreased markedly as the substrate moisture decreased.