Fig. 3.

Illustration of relevant substrates that have been considered for yeast fermentation. Heterologous enzymes that are currently applied are summarized for non-utilizable carbon sources in S. cerevisiae such as polymers (cellulose, starch, xylan), disaccharide (cellobiose, lactose, melibiose), pentose sugar (xylose, arabinose). In case of galactose, which is utilized slowly compared to glucose, over-expression targets of innate enzymes for improving galactose availability were screened