Abstract: Disclosed are an agarase mutant with improved thermal stability and application thereof, belonging to the fields of genetic engineering technology and enzyme engineering. The present disclosure provides an agarase mutant, which is obtained by mutating the amino acid at the 86th site, the 373rd site, the 374th site, the 496th site, the 507th site, or the 747th site of agarase with an amino acid sequence as shown in SEQ ID NO.1. The agarase mutant provided by the present disclosure improves the thermal stability and the hydrolytic activity of the agarase. Compared with the wild type enzyme, the mutant enzyme shows excellent heat resistance and can be industrially used at a relatively high temperature, so that the utilization rate of agar raw materials and the yield of oligosaccharides from agar are improved, and the mutant enzyme has a good industrial application prospect.

Abstract: The disclosure herein relates to a method for reducing the inhibitory effect of a cyclodextrin on a pullulanase and belongs to the technical field of gene engineering, enzyme engineering or food science. The method of the disclosure prepares a pullulanase mutant by reasonably mutating the key amino acid of the pullulanase interactive with the cyclodextrin to reduce the inhibitory effect of the cyclodextrin on the pullulanase, thereby improving the hydrolysis activity of the pullulanase. The disclosure finds the interactive sites of the pullulanase and the cyclodextrin based on analysis of crystal structures of enzymes and inhibitors and sequence comparison of enzymes from different sources, and utilizes site-directed mutation to obtain the pullulanase mutant having reduced sensibility to the cyclodextrin, thereby improving the utilization ratio of the starch raw material and the yield of the cyclodextrin.

Abstract: A method for screening adulteration of fibrate anti-hyperlipidemia chemicals in tea by combined method of high performance thin layer chromatography (HPTLC) and bioluminescence, which belongs to the field of food inspection. The method includes: firstly, formulating standard solutions of bezafibrate and ciprofibrate, and preparing a tea sample; pre-washing a thin-layer plate and then performing HPTLC spotting; performing HPTLC separation to move original mixed target objects mixed originally onto different positions of the thin-layer plate according to different molecular structures, so as to form a physical isolation; and subsequently, simultaneous detection of multiple targets in the tea sample could be realized conveniently through luminous bacteria coupled with the thin-layer plate by an immersed manner.

Abstract: The disclosure herein relates to a method for preparing branched cyclodextrin and application thereof, and belongs to the technical field of synthesis of branched cyclodextrin. The method comprises the following steps: (1) dissolving maltodextrin in a phosphate buffer solution, and adding CGTase for reacting; (2) reducing enzyme activity by a physical method; and (3) adding a saccharifying enzyme to the reaction system of step (2), and performing high-temperature enzyme deactivation to obtain the branched cyclodextrin. The method has mild reaction conditions, and at the same time, cyclodextrin and unreacted substrates can be hydrolyzed via the weak coupling activity of CGTase, thereby realizing effective separation of the branched cyclodextrin.

Abstract: A carbon skeleton reinforced porous starch and a preparation method thereof. The method of preparing the porous starch includes bonding starch to transition metal ions, then treating the starch attached with the transition metal ions and amylase via an extruding device, and finally forming a starch-based porous material having a high strength recombination structure, that is, the carbon skeleton reinforced porous starch.

Abstract: The disclosure herein relates to a method for reducing the inhibitory effect of a cyclodextrin on a pullulanase and belongs to the technical field of gene engineering, enzyme engineering or food science. The method of the disclosure prepares a pullulanase mutant by reasonably mutating the key amino acid of the pullulanase interactive with the cyclodextrin to reduce the inhibitory effect of the cyclodextrin on the pullulanase, thereby improving the hydrolysis activity of the pullulanase. The disclosure finds the interactive sites of the pullulanase and the cyclodextrin based on analysis of crystal structures of enzymes and inhibitors and sequence comparison of enzymes from different sources, and utilizes site-directed mutation to obtain the pullulanase mutant having reduced sensibility to the cyclodextrin, thereby improving the utilization ratio of the starch raw material and the yield of the cyclodextrin.

Abstract: The disclosure herein relates to a method for preparing branched cyclodextrin and application thereof, and belongs to the technical field of synthesis of branched cyclodextrin. The method comprises the following steps: (1) dissolving maltodextrin in a phosphate buffer solution, and adding CGTase for reacting; (2) reducing enzyme activity by a physical method; and (3) adding a saccharifying enzyme to the reaction system of step (2), and performing high-temperature enzyme deactivation to obtain the branched cyclodextrin. The method has mild reaction conditions, and at the same time, cyclodextrin and unreacted substrates can be hydrolyzed via the weak coupling activity of CGTase, thereby realizing effective separation of the branched cyclodextrin.