Cooray Sachindra T, Lee Jaslyn J L, Chen Wei Ning
Interdisciplinary Graduate School, Nanyang Technological University, 50 Nanyang Avenue, Singapore, 639798, Singapore.
Advanced Environmental Biotechnology Centre, Nanyang Environment & Water Research Institute, Nanyang Technological University, 1 CleanTech Loop, Singapore, 637141, Singapore.
AMB Express. 2017 Dec;7(1):117. doi: 10.1186/s13568-017-0414-1. Epub 2017 Jun 5.
Brewers' spent grain (BSG) is a by-product generated from the beer manufacturing industry, which is extremely rich in protein and fiber. Here we use low cost BSG as the raw material for the production of a novel growth media, through a bioconversion process utilizing a food grade fungi to hydrolyze BSG. The novel fermentation media was tested on the yeast Rhodosporidium toruloides, a natural yeast producing carotenoid. The yeast growth was analysed using the growth curve and the production of intracellular fatty acids and carotenoids. Untargeted GCMS based metabolomics was used to analyse the constituents of the different growth media, followed by multivariate data analysis. Growth media prepared using fermented BSG was found to be able to support the growth in R. toruloides (21.4 mg/ml) in comparable levels to YPD media (24.7 mg/ml). Therefore, the fermented BSG media was able to fulfill the requirement as a nitrogen source for R. toruloides growth. This media was able to sustain normal metabolomics activity in yeast, as indicated by the level of fatty acid and carotenoid production. This can be explained by the fact that, in the fermented BSG media metabolites and amino acids were found to be higher than in the unfermented media, and close to the levels in YPD media. Taken together, our study provided evidence of a growth media for yeast using BSG. This should have potential in replacing components in the current yeast culture media in a sustainable and cost effective manner.
啤酒糟是啤酒制造业产生的一种副产品，富含蛋白质和纤维。在这里，我们以低成本的啤酒糟为原料，通过利用食品级真菌水解啤酒糟的生物转化过程，生产一种新型生长培养基。在天然产类胡萝卜素的酵母——红酵母上测试了这种新型发酵培养基。使用生长曲线分析酵母生长情况，并分析细胞内脂肪酸和类胡萝卜素的产量。基于非靶向气相色谱 - 质谱联用的代谢组学用于分析不同生长培养基的成分，随后进行多变量数据分析。发现使用发酵啤酒糟制备的生长培养基能够支持红酵母的生长（21.4毫克/毫升），与YPD培养基（24.7毫克/毫升）相当。因此，发酵啤酒糟培养基能够满足作为红酵母生长氮源的要求。如脂肪酸和类胡萝卜素的产量水平所示，这种培养基能够维持酵母正常的代谢组学活性。这可以通过以下事实来解释：在发酵啤酒糟培养基中发现的代谢物和氨基酸高于未发酵培养基，且接近YPD培养基中的水平。综上所述，我们的研究为使用啤酒糟作为酵母生长培养基提供了证据。这在以可持续且经济高效的方式替代当前酵母培养基中的成分方面应具有潜力。
