Genome Shuffling of Aspergillus niger for Improving Transglycosylation Activity

Abstract

Isomaltooligosaccharides (IMO), the glucosylsaccharides used as food additives, are made from saccharified starch by enzymes or microbial cells with transglycosylation activity. This study aimed to generate shuffled futants of Aspergillus niger with enhanced transglycosylation activity for industrial IMO production. The starting mutant population was generated by (60)Co-γ radiation; mutants with higher transglycosylation activity were selected and subjected to recursive protoplast fusion. The resulting fusants were screened by a novel high-throughput method based on detecting non-fermentable reducing sugar. After three rounds of genome shuffling, the best performing strain GS3-3 was obtained, its transglycosylation activity (14.91 U/mL) was increased by 194.1 % compared to that of original strain C-6181. In fermentor test, transglycosylation activity of GS3-3 was obtained at 16.61 U/mL. The mycelia of GS3-3 were reused ten times to produce IMO syrup from liquefied cassava starch containing about 280 g/L total sugar within 4 days. The conversion of liquefied cassava starch to IMO was at 71.3-72.1 %, which was higher than the best conversion (68 %) ever reported. GS3-3 shows a great potential for industrial IMO production.

Process optimization of β-glucosidase production by a mutant strain, Aspergillus niger C112

“…Currently, much effort has been focused on strain improvement, culture medium, process optimization, etc., to enhance the efficient production of BGL. For example, chemical reagents such as ethyl methanesulfonate, acridine orange, and N-methyl N'-nitro-N-nitrosoguanidine, (Pal and Das 2005;Lotfy et al 2007;Wang et al 2016), ultraviolet irradiation (Mahalakshmi et al 2009), gamma radiation (Ottenheim et al 2015), genome shuffling (Li et al 2014), protoplast fusion (Khattab and Bazaraa 2005), and regulation target encoding genes (Stricker et al 2008) were used for A. niger improvement. The feed stock (e.g.…”

Non-sterile Submerged Fermentation of Fibrinolytic Enzyme by Marine Bacillus subtilis Harboring Antibacterial Activity With Starvation Strategy

“…Escherichia coli DH5α, Lactobacillus sp. PL17, Pichia pastoris GS115, Saccharomyces cerevisiae GXJ-1 (Chen et al, 2011), and Aspergillus niger GS3-3 (Li et al, 2014) preserved in our lab were used as indicator strains for antimicrobial assay.…”

Improvement of Bacillus subtilis for poly‐γ‐glutamic acid production by genome shuffling

“…Comparing with genetic engineering, it allows genetic changes at whole genome level and does not require the genome sequence data and metabolic network information (Zhang et al ., ; Biot‐Pelletier and Martin, ). Recent reports have described the use of genome shuffling to improve production of lipopeptide by B. amyloliquefaciens (Zhao et al ., ), avilamycin by Streptomyces viridochromogenes (Lv et al ., ) and transglycosylation activity by Aspergillus niger (Li et al ., ). However, genome shuffling method has not been applied to improve the production of γ‐PGA.…”