Details

Autor(en) / Beteiligte

• Li, Yan-xiao
• Yi, Ping
• Wang, Nan-nan
• Liu, Jun
• Liu, Xue-qiang
• Yan, Qiao-juan
• Jiang, Zheng-qiang

Titel

High level expression of β-mannanase (RmMan5A) in Pichia pastoris for partially hydrolyzed guar gum production

Ist Teil von

• International journal of biological macromolecules, 2017-12, Vol.105 (Pt 1), p.1171-1179

Ort / Verlag

Netherlands: Elsevier B.V

Erscheinungsjahr

2017

Quelle

MEDLINE

Beschreibungen/Notizen

• Partially hydrolyzed guar gum (PHGG), an important supplemental dietary fiber, has been used as food ingredient in many industries. In this study, a novel β-mannanase gene (RmMan5A) from Rhizomucor miehei was successfully expressed in Pichia pastoris and subjected for PHGG production. Enzyme activity of fermentation supernatant reached 85,200UmL−1 after 168h high cell density fermentation. The purified RmMan5A exhibited the highest enzyme activity at pH 7.0 and 65°C. RmMan5A was then employed for guar gum hydrolysis and PHGG obtained demonstrated a weight-average molecular weight (Mw) of 2.5×104Da. Total dietary fiber accounted 90.6% of PHGG and 24.9% (w/w) of PHGG were identified as manno-oligosaccharides with degree of polymerization<7. PHGG was further fractionated (F1–F4) by gradual ethanol precipitation. PHGG F1 with an Mw value of 3.6×104Da and a mannose/galactose (M/G) ratio of 1.47 was precipitated initially, followed by PHGG F2 and F3 which showed lower Mw and higher M/G ratio. According to the structure analysis, the distribution of α-d-galactose of PHGG F1 was compact and regular, and that of other fractions was more random. A suitable β-mannanase for PHGG production and some useful information of PHGG are provided in this paper.