In the present study Trichoderma

In the present study, Trichoderma viride β-glucosidase was screened in our laboratory and used for the synthesis of gentiooligosaccharides via reverse hydrolysis and transglycosylation.
Material and methods
Results and discussion
Conclusions In the present study, the T. viride β-glucosidase gene bgl1 was ligated into the vector pPIC9K and co-expressed in P. pastoris KM71 with the disulfide isomerase pdi. Optimization of fermentation achieved a β-glucosidase activity of 1402 U/ml in the culture medium, which is 23.4-fold higher than the highest level of T. viride β-glucosidase expression reported previously. We also used the reverse hydrolysis activity of β-glucosidase to synthesise gentiooligosaccharides using a high concentration of glucose as substrate, achieving a yield of 130 g/l and a conversion rate of 16.25%, which is the most efficient gentiooligosaccharide synthesis from glucose reported to date. We also performed gentiooligosaccharide synthesis from a mixture of glucose and cellobiose as substrates via β-glucosidase-catalysed transglycosylation and achieved a yield of 116 g/l and a conversion rate of 19.4%.
Notes
Acknowledgements This work was supported financially by the National Science Fund for Distinguished Young Scholars (31425020); the 111 Project (No. 111-2-06); the National Natural Science Foundation of China (31571776); the Key Research and Development Program of Jiangsu Province (BE2015751 and BE2017319); and the Fundamental Research Funds for the Central Universities (JUSRP51706A); the Natural Science Foundation of Jiangsu Province (BK20171261).
Introduction Diabetes mellitus mostly characterized by hyperglycemia and their complications (neuropathy, nephropathy and retinopathy) increase the morbidity and mortality risks for the patients [1], [2]. It is estimated that about 90% of the world’s diabetic people have Type 2 Estradiol Benzoate receptor [3], [4], [5]. Poor control of the post-prandial glucose levels, related with type-2 diabetes mellitus, leads to on-set of atherosclerosis and other cardiovascular disorders [6], [7]. α-Glucosidase enzyme (EC 3.2.1.20) catalyzes the cleavage of oligosaccharides to glucose in the small intestine. Its inhibition can contribute to the control over the post-prandial hyperglycemia and thereby prevents diabetic complications [8]. α-Glucosidase inhibitors (AGIs), such as acarbose, voglibose and miglitol, compete with the oligosaccharides for the binding of the enzyme and successfully decrease the post-prandial glucose levels in type-2 diabetes patients [8]. However, these classic AGIs are known to cause flatulence, diarrhea and abdominal discomfort and having low efficacy with high IC50 values against the enzyme [9]. Clinically approved anti-diabetic drugs have restricted safety alarms, and temporally improve blood glucose levels, improves diabetes complications, as well as in the treatment of obesity [10] but accompanied with gastrointestinal side-effects [11]. The consumption of natural products is known to have anti-diabetic effects, offering numerous exciting potentials for the future progress and development of successful therapies [5], [10]. Due to the essential role of this enzyme in hyperglycemia and specially the side effects of the existing drugs, the basic requirement is to discover safe and effective enzyme inhibitors as an approach to effectively control the diabetic disorders. The oleo gum resin (frankincense) of Boswellia species and its individual components has shown numerous biological applications including anti-inflammatory, leukotriene biosynthesis-inhibitory and anti-tumor activities [12], [13], [14], [15]. A group of pentacyclic triterpenoids (Boswellic acids; BAs) are usually isolated from the resins of Boswellia spp. and considered the key bioactive components of frankincense [16]. Their biological activities against ulcerative colitis, asthma, chronic colitis, hepatitis, inflammation, and arthritis are well documented [14], [17], [18], [19], [20], [21], [22], [23]. BAs are also reported to inhibit growth and effect apoptosis in brain tumors, colon cancer cells, malignant glioma cells, and leukemia cells [24], [25], [26], [27].