May 14, 2022
To,
Editor-in-Chief
Biotechnology Journal
Subject: Manuscript submission
Dear Prof. Alois Jungbauer:
Please consider our manuscript entitled “Construction,
expression and application of microbial β-1,3-glucanase for β-1,3-glucan
oligosaccharide production ” for publication as a Review Article inBiotechnology Journal .
β-1,3-Glucan oligosaccharides produced by enzymatic hydrolysis of
β-1,3-glucans have attracted great interest, because they possess
biological functionalities such as disease-resistance in plants,
immuno-modulating activities in animals and anti-tumor properties.
β-1,3-Glucanase with high specific activity is a prerequisite for the
industrial preparation of glucan oligosaccharides. These enzymes are
widely distributed in bacteria, fungi, plants and invertebrates, and are
classified into glycoside hydrolase families 3, 5, 16, 17, 55, 64, 72,
81, 128 and 132. Different endo-β-1,3-glucanases produce various
hydrolysates with different degrees of polymerization, which can be used
not only to prepare oligosaccharides with multiple biological functions,
but also to understand chemical structures and biological functions of
polysaccharides.
The early research of our team focused on the fermentation condition
optimization for the production of β-1,3-glucanase by wild-typeTrichoderma harzianum GIM 3.442. Coupled fermentation systems ofT. harzianum GIM 3.442 and Agrobacterium sp. ATCC
31749/Sclerotium rolfsii WSH-G01/Schizophyllum communeGDMCC 5.43 were established for producing linear and branched
β-1,3-glucooligosaccharides. Then, endo-β-1,3-glucanase gene
(BGN ) from T. harzianum was expressed in P.
pastoris GS115 with promoter optimization (pGAP), and a mutant
endo-β-1,3-glucanase was obtained by implementing error-prone PCR
technology, and the specific activity towards curdlan was much higher
than the original enzyme (292 U/mg) and other reported enzymes, such as
recombinant Blg32 from Bacillus lehensis (233.01 U/mg) and Endo23
from Trichoderma teesei GIMCC 3.498(1.52 U/mg). One-step
production of functional branched glucan oligosaccharides was
established with coupled fermentation of P. pastoris and S.
rolfsii , the maximum yield of β- glucan oligosaccharides (DP 2–17) was
12.71 g/L in a 7-L bioreactor.
In order to improve the endo-β-1,3-glucanase catalytic efficiency and
expression level, great efforts have been made to develop effective
enzyme engineering and fermentation strategies. Numerous genes encoding
endo-β-1,3-glucanases have been isolated and characterized from various
organisms, and can be produced in high yields by recombinant expression
methods. This report presents the research progress on the construction
and expression of β-1,3-glucanase in Escherichia coli andP. pastoris from different microorganisms. Culture conditions and
strategies to improve enzyme activity in these hosts are summarized. The
application of β-1,3-glucanase in degradation of different β-1,3-glucans
(curdlan, scleroglucan, laminarin, and schizophyllan) and their
hydrolysate analysis are reviewed. It also summarizes the structural
differences and healthy functional activities of different types of
oligosaccharides. This study provides an important reference for further
modification and utilization of microbial β-1,3-glucanases in
large-scale production of multi-functional oligosaccharides.
I, as the corresponding author, on behalf of all co-authors of the paper
declare that this manuscript has not been previously published and is
not currently submitted for review to any other journal. All authors
declare no conflict of interest. We would greatly appreciate your kind
attention on this submission and look forward to the helpful comments
from you and other referees.
Please let us know if we can provide any additional information to
facilitate your assessment of the suitability of our work for
publication in BTJ .
Sincerely yours,
Minjie Gao