RESUMO
Most commercial media for mammalian cell culture are designed to satisfy the amino acid requirements for cell growth, but not necessarily those for recombinant protein production. In this study, we analyze the amino acid consumption pattern in naïve and recombinant Chinese hamster ovary (CHO) cell cultures. The recombinant model we chose was a CHO-S cell line engineered to produce a monoclonal antibody. We report the cell concentration, product concentration, and amino acid concentration profiles in naïve and recombinant cell cultures growing in CD OptiCHO™ medium with or without amino acid supplementation with a commercial supplement (CHO CD EfficientFeed™ B). We quantify and discuss the amino acid demands due to cell growth and recombinant protein production during long term fed batch cultivation protocols. We confirmed that a group of five amino acids, constituting the highest mass fraction of the product, shows the highest depletion rates and could become limiting for product expression. In our experiments, alanine, a non-important mass constituent of the product, is in high demand during recombinant protein production. Evaluation of specific amino acid demands could be of great help in the design of feeding/supplementation strategies for recombinant mammalian cell cultures.
RESUMO
This contribution examines the technical feasibility of producing high added value probiotic biomass from deproteinized and non-supplemented milk whey. The kinetics of growth of Lactobacillus casei in deproteinized goat milk whey was analyzed. Experiments in batch, continuous and fed-batch conditions were conducted in a 3 L fully instrumented bioreactor. Final substrate and biomass concentrations, yields and productivities are reported for different culture strategies. A kinetic analysis was conducted to characterize biomass production, product inhibition effects, and substrate consumption rates. Due to the strong product inhibition, fed-batch cultures at high biomass concentration rendered higher productivity (0.45 g L(-1) h(-1)) than batch and continuous cultures (0.11 g L(-1) h(-1)), complete lactose conversions (<1.0 g of lactose/L at the end of each fed-batch cycle), and a product with higher viable cell counts (2 x 10(10) cell/g of freeze-dried product). Based on our result, high-cell density fed-batch strategies are recommended for commercial production of probiotic L. casei biomass.
Assuntos
Reatores Biológicos , Biotecnologia/métodos , Lacticaseibacillus casei/crescimento & desenvolvimento , Leite/química , Probióticos , Animais , Biomassa , Cromatografia Líquida de Alta Pressão , Fermentação , Cabras , CinéticaRESUMO
BTEX removal under aerobic conditions by unleaded gasoline acclimated biomass and BTEX acclimated biomass, and the effect of surfactant on BTEX biodegradation were evaluated. The effect of BTEX concentration as the sole source of carbon for biomass acclimation and the effect of yeast extract on cell growth in unleaded gasoline-fed reactors were also evaluated. For the unleaded gasoline acclimated biomass, benzene was shown the most recalcitrant among all BTEX, followed by o-xylene and toluene with 16-23%, 35-41% and 57-69% biodegradation, respectively. Ethylbenzene was consistently the fastest BTEX chemical removed with 99% biodegradation for the four bioreactor acclimated biomasses tested. For the 1,200 ppm BTEX acclimated biomass, benzene showed the highest removal efficiency (99%) among the four biomass environmental conditions tested, along with 99% toluene and 99% ethylbenzene biodegradation. O-xylene showed 92-94% removal. In all bioassays tested Tergitol NP-10 was fully removed, and did not have a substantial effect on BTEX biodegradation at the end of a 10-day evaluation.