VTT Technical Research Centre of Finland, Espoo, 02044 VTT, Finland.
Department of Biochemistry and Molecular Biology, Federal University of Paraná, Curitiba-PR, 81531-990, Brazil.
AMB Express. 2014 Mar 18;4:33. doi: 10.1186/s13568-014-0033-z. eCollection 2014.
Citrus processing waste is a leftover from the citrus processing industry and is available in large amounts. Typically, this waste is dried to produce animal feed, but sometimes it is just dumped. Its main component is the peel, which consists mostly of pectin, with D-galacturonic acid as the main monomer. Aspergillus niger is a filamentous fungus that efficiently produces pectinases for the hydrolysis of pectin and uses the resulting D-galacturonic acid and most of the other components of citrus peel for growth. We used engineered A. niger strains that were not able to catabolise D-galacturonic acid, but instead converted it to L-galactonic acid. These strains also produced pectinases for the hydrolysis of pectin and were used for the conversion of pectin in orange peel to L-galactonic acid in a consolidated process. The D-galacturonic acid in the orange peel was converted to L-galactonic acid with a yield close to 90%. Submerged and solid-state fermentation processes were compared.
柑橘加工废料是柑橘加工业的一种废弃物，其产量很大。通常，这种废料会被干燥以生产动物饲料，但有时也会被直接丢弃。它的主要成分是果皮，主要由果胶组成，其主要单体是 D-半乳糖醛酸。黑曲霉是一种丝状真菌，能有效地产生果胶酶来水解果胶，并利用由此产生的 D-半乳糖醛酸和柑橘皮的大部分其他成分进行生长。我们使用了经过基因工程改造的黑曲霉菌株，这些菌株不能代谢 D-半乳糖醛酸，而是将其转化为 L-半乳糖醛酸。这些菌株还能产生用于果胶水解的果胶酶，并用于在一个整合的过程中，将橙皮中的果胶转化为 L-半乳糖醛酸。橙皮中的 D-半乳糖醛酸几乎全部转化为 L-半乳糖醛酸，转化率接近 90%。比较了浸没式发酵和固态发酵过程。
