CAROTENOID PRODUCTION BY Sporidiobolus pararoseus IN AGROINDUSTRIAL MEDIUM: OPTIMIZATION OF CULTURE CONDITIONS IN SHAKE FLASKS AND SCALE-UP IN A STIRRED TANK FERMENTER

Abstract Biotechnological production of carotenoids can be affected by cultivation conditions, such as temperature, pH and agitation. The aim of this study was to maximize carotenoid production by Sporidiobolus pararoseus in shake flasks with agroindustrial by-products as substrates. The best conditions were used in a stirred tank fermenter. The medium consisted of corn steep liquor and sugar cane molasses pretreated with sulfuric acid. In order to evaluate the effects of the variables, a central composite rotatable design was used. The highest values of total carotenoids (565 µg L-1), biomass (13.6 g L-1) and Yp/s (10.9 µg g-1) were obtained in Assay 13 at 27.5ºC, 150 rpm and pH=4, in Erlenmeyer flasks. For the best conditions defined for carotenoid productivity and 1.2 vvm in the stirred tank fermenter, the maximum value was 1969.3 µg L-1 of total carotenoids. It was 3.5-fold higher than the value obtained when shake flasks were used.

摘要：类胡萝卜素（carotenoids）的生物技术合成可受培养条件影响，包括温度、pH值与搅拌速率。本研究旨在以农业工业副产物为底物，通过摇瓶（shake flasks）发酵最大化类红冬孢酵母菌（Sporidiobolus pararoseus）的类胡萝卜素产量，并将摇瓶实验确定的最优培养条件应用于搅拌罐式发酵罐（stirred tank fermenter）中。发酵培养基由经硫酸预处理的玉米浆与甘蔗糖蜜组成。为评估各变量的影响，本研究采用了中心复合旋转设计（central composite rotatable design）。在锥形摇瓶（Erlenmeyer flasks）中，于27.5℃、150 rpm、pH=4的第13号实验组内，获得了最高的总类胡萝卜素产量（565 μg·L⁻¹）、生物量（13.6 g·L⁻¹）与产物底物得率Yp/s（10.9 μg·g⁻¹）。以类胡萝卜素生产效率为目标确定最优条件，并在搅拌罐式发酵罐中设置1.2 vvm的通气量，最终总类胡萝卜素产量达到1969.3 μg·L⁻¹，较摇瓶发酵获得的结果提升了3.5倍。