Mixotrophic continuous flow cultivation of Chlorella protothecoides for lipids.

The oleaginous alga Chlorella protothecoides accumulates lipid in its biomass when grown in nitrogen-restricted conditions. To assess the relationship between nitrogen provision and lipid accumulation and to determine the contribution of photosynthesis in mixotrophic growth, C. protothecoides was grown in mixo- and heterotrophic nitrogen-limited continuous flow cultures. Lipid content increased with decreasing C/N, while biomass yield on glucose was not affected. Continuous production of high lipid levels (57% of biomass) was possible at high C/N (87-94). However, the lipid production rate (2.48 g L(-1) d(-1)) was higher at D=0.84 d(-1) with C/N 37 than at D=0.44 d(-1) and C/N 87 even though the lipid content of the biomass was lower (38%). Photosynthesis contributed to biomass and lipid production in mixotrophic conditions, resulting in 13-38% reduction in CO2 production compared with heterotrophic cultures, demonstrating that photo- and heterotrophic growth occurred simultaneously in the same population.

Bacterial Concentration and Diversity within Repetitive Aliquots Collected from Replicate Continuous-Flow Bioreactor Cultures.

The aim of this study was to determine the reproducibility of small volume repeat sampling from replicate bioreactors with stabilized continuous-flow chicken cecal bacterial communities. Bacterial concentration and diversity were analyzed by phenotypic, biochemical and ribotype analysis. Significant differences in concentrations and variations in diversity were found in replicate bioreactors.

The continuous flow culture as an in vitro model in experimental mycology.

We used the model of continuous flow culture (cfc) to study the growth of Candida species. This model allows special test conditions: a long generation time of 15-20 hs, controlled limitation of nitrogen sources and carbohydrates, comparison of the growth under aerobic and anaerobic conditions simultaneously. These conditions were used to study the effect of antimycotic drugs, mainly during a long time of 7 to 10 days. Germ tube formation as a virulence factor was more abundant and faster in cfc of strains with a stronger adherence to buccal epithelium cells. Co-cultivation of C. albicans and C. glabrata allowed conclusions for their colonization in vivo. A biofilm on the glass wall of the culture vessel led to mycelium formation by C. albicans. Concomitantly the growth of C. glabrata was favoured. Growth of C. albicans in the gastrointestinal flora was reduced by masses of bacteria and their multiple metabolic activities. A remarkable growth of C. albicans was only to be seen if the ecosystem was destroyed e.g. by antibacterial antibiotics. The influence of fluconazole in a long-term follow up study under anaerobic conditions showed an inhibition of C. albicans in 99.9 %. This means fungicidal efficacy.

Plant regeneration from protoplasts of Laminaria japonica Areschoug (Laminariales, Phaeophyceae) in a continuous-flow culture system.

A continuous-flow culture system was developed for culturing Laminaria japonica protoplasts. Protoplasts were settled on 5-µm pore size nylon mesh fixed inside a 50-ml plastic syringe, and cultured in Provasoli's enriched seawater with iodine medium with a gentle upward flow generated by a peristaltic pump. In the culture system, 50% of the protoplasts regenerated their cell wall within 24 hours and almost all protoplasts regenerated a cell wall after 3 days culture. After cell wall regeneration, a number of cells divided and regenerated into sheet-shaped thalli. The thalli transferred to a tissue culture flask developed into sporophyte-like plantlets within 1 month. Plantlets then differentiated into blade, stipe, and holdfast, with a proper mucilage canal.

Maintenance of the Biological Efficacy in Chicks of a Cecal Competitive-Exclusion Culture against Salmonella by Continuous-Flow Fermentation.

A competitive-exclusion culture was isolated by the continuous-flow culture of chicken cecal bacteria. The original continuous-flow culture and a continuous-flow culture derived from a lyophilized sample of it that had been stored for 180 days at -70°C were provided to day-old chicks. Experiments utilizing the original culture were performed after 5, 30, 100, and 365 days of continuous-flow conditions and the lyophilized culture after 5 days of continuous-flow culture. In all experiments chicks were challenged with 104 CFU of Salmonella typhimurium at 3 days of age. At 10 days of age the chicks were killed and cecal contents analyzed for fermentation parameters and for S. typhumurium colonization. Ten-day-old chicks provided with the original or the lyophilized culture had significantly increased cecal propionic acid (P < 0.05) and decreased Salmonella cecal colonization (P < 0.05) compared to untreated controls in all experiments. The results indicate that continuous-flow cultures can be used as a practical method to maintain competetive-exclusion cultures without loss of efficacy, and continuous-flow cultures stored in a lyophilized form can be reconstituted and still maintain efficacy.