Manipulation of an α-glucosidase in the industrial glucoamylase-producing Aspergillus niger strain O1 to decrease non-fermentable sugars production and increase glucoamylase activity

Multidimensional analysis of wheat original crucial endogenous enzymes driving microbial communities metabolism during high-temperature Daqu fermentation

Knowledge of the metabolism of functional enzymes is the key to accelerate the transformation and utilization of raw materials during high temperature Daqu (HTD) manufacturing. However, the metabolic contribution of raw materials-wheat is always neglected. In this research, the relationship between the metabolism of wheat and microorganisms was investigated using physicochemical and sequencing analysis method. Results showed that the process of Daqu generation was divided into three stages based on temperature. In the early stage, a positive correlation was found between Monascus, Rhizopus and glucoamylase metabolism (r > 0.8, p < 0.05). Meanwhile, the glucoamylase metabolism in wheat occupied 63.8 % of the total matrix at the day 4. In the middle to later stages, the wheat metabolism of proteases, α-amylases and lipases in gradually reached their peak. Additionally, Lactobacillus and α-amylases presented a positive correlation (r > 0.7, p < 0.05), and the α-amylases metabolism in wheat occupied 22.18 % of the total matrix during the same time period. More importantly, the changes of enzyme activity metabolic pathway in wheat and microorganism were reflected by respiratory entropy (RQ). Overall, these results guide the choice of substrate during Daqu production.

Effective bioconversion of fungal-spoiled starchy food waste into fermentable sugars using fungi-degrading, artificial amylosomes

Fungi-degrading artificial amylosomes were newly developed consisting of fungi-degrading enzyme (NAG), starch-degrading enzymes and a scaffold protein. Amylosome scaffolds containing starch-binding proteins (SbpCbpA and CCSbpCbpA) were highly bound to starch and fungal-spoiled food waste. Amylosomes showed an average of 1.43-fold higher reducing sugar production from starch. 2.00-fold α-amylase in amylosomes increased reducing sugar production from amylose by an average of 1.50-fold. At 70°C for 6 hours, SbpCbpA and CCSbpCbpA maintained an average activity of 56.42% compared to the control (38.37%). The enzyme mixture and amylosomes with NAG showed an average 1.31-fold increase in glucose production in response to fungal-spoiled food waste compared to samples without NAG; in particular, CCSbpCbpA with NAG produced 62.44 ± 0.03 mM glucose (2.55-fold of the enzyme mixture without NAG). This research strategy can be applicable to the starch and fungal-spoiled food waste saccharification in an ecofriendly manner, leading to sugar production in industrial fields.