Regulation of CCR in the γ-CGTase production from Bacillus macorous by the specific cell growth rate control

Unveiling the potential of specific growth rate control in fed-batch fermentation: bridging the gap between product quantity and quality

During the epoch of sustainable development, leveraging cellular systems for production of diverse chemicals via fermentation has garnered attention. Industrial fermentation, extending beyond strain efficiency and optimal conditions, necessitates a profound understanding of microorganism growth characteristics. Specific growth rate (SGR) is designated as a key variable due to its influence on cellular physiology, product synthesis rates and end-product quality. Despite its significance, the lack of real-time measurements and robust control systems hampers SGR control strategy implementation. The narrative in this contribution delves into the challenges associated with the SGR control and presents perspectives on various control strategies, integration of soft-sensors for real-time measurement and control of SGR. The discussion highlights practical and simple SGR control schemes, suggesting their seamless integration into industrial fermenters. Recommendations provided aim to propose new algorithms accommodating mechanistic and data-driven modelling for enhanced progress in industrial fermentation in the context of sustainable bioprocessing.

gamma-Cyclodextrin: a review on enzymatic production and applications

Cyclodextrins are cyclic alpha-1,4-glucans that are produced from starch or starch derivates using cyclodextrin glycosyltransferase (CGTase). The most common forms are alpha-, beta-, and gamma-cyclodextrins. This mini-review focuses on the enzymatic production, unique properties, and applications of gamma-cyclodextrin as well as its difference with alpha- and beta-cyclodextrins. As all known wild-type CGTases produce a mixture of alpha-, beta-, and gamma-cyclodextrins, the obtaining of a CGTase predominantly producing gamma-cyclodextrin is discussed. Recently, more economic production processes for gamma-cyclodextrin have been developed using improved gamma-CGTases and appropriate complexing agents. Compared with alpha- and beta-cyclodextrins, gamma-cyclodextrin has a larger internal cavity, higher water solubility, and more bioavailability, so it has wider applications in many industries, especially in the food and pharmaceutical industries.

Production of cyclodextrin glycosyltransferase by alkaliphilic Bacillus circulans in submerged and solid-state cultivation

Cyclodextrin glycosyltransferase (CGTase; E.C. 2.4.1.19) is an industrially important enzyme, which is used to produce cyclodextrins (CDs). In this research, we report the use of experimental factorial design to find the best conditions of pH and temperature for CGTase production by Bacillus circulans var. alkalophilus. The optimized calculated values for the tested variables were, respectively, pH 9.7 and temperature 36 degrees C, with a CGTase activity of 615 U mL(-1). The CGTase production was further studied with the optimized process parameters on submerged cultivations (SC) and solid-state cultivations (SSC) using soybean industrial fibrous residue (SIFR). The maximum CGTase activity obtained on SC was 1,155 U mL(-1) under aerobic conditions. Cell growth and CGTase synthesis in SSC using SIFR as substrate was excellent, with CGTase activity of 32,776 U g ((SIFR))(-1). These results strongly support the use of SIFR for CGTase production since it is a non-expensive residue.