Evaluation of the process conditions for the production of microbial carotenoids by the recently isolated Rhodotorula mucilaginosa URM 7409

Abstract This study aimed to improve the physical and nutritional process conditions for the production of carotenoids by the newly isolated Rhodotorula mucilaginosa, a red basidiomycete yeast. The carotenoid bioproduction was improved using an experimental design technique, changing the process characteristics of agitation (130 rpm to 230 rpm) and temperature (25 °C to 35 °C) using seven experiments, followed by a 25-1 fractional design to determine the relevant factors that constitute the culture medium (glucose, malt extract, yeast extract, peptone and initial pH). A complete second order experimental design was then carried out to optimize the composition of the culture medium, the variables being yeast extract (0.5 to 3.5 g/L), peptone (1 to 5 g/L) and the initial pH (5.5 to 7.5), with 17 experiments. The maximum carotenoid production was 4164.45 μg/L (252.99 μg/g), obtained in 144 h in YM (yeast malt) medium with 30 g/L glucose, 10 g/L malt extract, 2 g/L yeast extract, 3 g/L peptone, an initial pH 6, 130 rpm and 25 °C, demonstrating the potential of this yeast as a source of bio-pigments. In this work, the nitrogen sources were the factors that most influenced the intracellular accumulation of carotenoids. The yeast R. mucilaginosa presented high production at a bench level and may be promising for commercial production. Resumo Este estudo teve como objetivo melhorar as condições físicas e nutricionais do processo de produção de carotenoides pela recém-isolada Rhodotorula mucilaginosa, uma levedura basidiomiceta vermelha. A melhoria da bioprodução de carotenoides foi obtida pela técnica de delineamento experimental, alterando as características dos processos [agitação (130 rpm a 230 rpm) e temperatura (25 °C a 35 °C)] com sete experimentos, e após um planejamento fracionário 25-1 para a classificação dos fatores relevantes que constituem o meio de cultura (glicose, extrato de malte, extrato de levedura, peptona e pH inicial). Um delineamento experimental de segunda ordem completo foi realizado para otimizar a composição do meio de cultura e as variáveis foram: extrato de levedura (0,5 a 3,5 g/L), peptona (1 a 5 g/L) e pH inicial (5,5 a 7,5), com 17 experimentos. A produção máxima de carotenoide foi de 4.164,45 μg/L (252,99 μg/g) em 144 h, em meio YM com 30 g/L de glicose, 10 g/L de extrato de malte, 2 g/L de extrato de levedura e 3g/L de peptona, e pH inicial 6, 130 rpm a 25 °C. Neste trabalho, as fontes de nitrogênio foram os fatores que mais influ