Bernard Marin

Potential of solid state fermentation for production of L(+)-lactic acid by Rhizopus oryzae

Production of l(+)-lactic acid by Rhizopus oryzae NRRL 395 was studied in solid medium on sugar-cane bagasse impregnated with a nutrient solution containing glucose and CaCO3. A comparative study was undertaken in submerged and solid-state cultures. The optimal concentrations in glucose were 120 g/l in liquid culture and 180 g/l in solid-state fermentation corresponding to production of l(+)-lactic acid of 93.8 and 137.0 g/l, respectively. The productivity was 1.38 g/l per hour in liquid medium and 1.43 g/l per hour in solid medium. However, the fermentation yield was about 77% whatever the medium. These figures are significant for l(+)-lactic acid production.

Breeding and growth of Rhizopus in raw cassava by solid state fermentation

Nineteen Rhizopus strains were selected and tested for their growth capacity on raw cassava starch and their ability to produce amylase when grown on solid-state fermentations. Only three strains grew significantly on this natural substrate. Glucoamylase production was higher on raw cassava than on cooked cassava. After 48 h of fermentation, the protein content of cassava was increased from 1.75% to 11.3%. The byproducts of fermentation were fumaric acid, lactid acid and ethanol.

Growth kinetics of Rhizopus arrhizus in solid state fermentation of treated cassava

Growth kinetics of Rhizopus arrhizus MUCL 28168 were determined for different treatments of cassava during solid state fermentation. The best case gave a specific growth rate (μ) of 0.24 h-1, a yield calculated on a basis that oxygen consumption (Yx/o) was 2.9 g biomass. g-1 O2 consumed and the maintenance coefficient (m) was 0.004 g O2 consumed. g-1 biomass. h-1.

A New HPLC Analytical Method to Study Fungal Caffeine Metabolism

A simple and rapid HPLC method has been developed to analyse all the methylxanthines that can be produced by N-demethylation of 1,3,7-trimethylxanthine (caffeine). This method is particularly suitable to study caffeine metabolism of a filamentous fungus (Aspergillus sp V12A25) cultivated in a synthetic liquid medium containing caffeine as the sole source of nitrogen.

Cultivation of Lentinula edodes on mixture of cassava bagasse and sugarcane bagasse

Potential of the production of Lentinula edodes (shiitake) mushrooms on agro-industrial residues, such as cassava bagasse and sugarcane bagasse, is evaluated under solid state fermentation. Visual observations in flaskes and also plastic bags indicated good growth on these substrates. The fructification and biological efficiency of the process was found to be good. Best results for basiodiocarp production were evident in the medium containing 80% cassava bagasse + 20% sugarcane bagasse (w/w). Data on kinetics of starch consumption and protein synthesis showed the consumption of 77.42% starch during the biotransformation process, with three times increase in protein content. Fructification was achieved after 60 days of inoculation and it amounts to decrease by 7 times, as compared to the conventional process of the production on oak tree logs. The results provide a novel alternate technology for shiitake production on the mixture of cassava bagasse and sugarcane bagasse.