Authors: Bollok, Monika¹; Henriksson, Hongbin¹; Kallas, Åsa¹; Jahic, Mehmedalija¹; Teeri, Tuula¹; Enfors, Sven-Olof²

Source: Applied Biochemistry and Biotechnology, Volume 126, Number 1, February 2005 , pp. 61-77(17)

Publisher: Humana Press

Abstract:

The gene XET16A encoding the enzyme xyloglucan endotransglycosylase (XET) from hybrid aspen (Populus tremula xtremuloides Mich) was transformed into Pichia pastoris GS115 and the enzyme was secreted to the medium. The influence of process conditions on the XET production, activity, and proteolytic degradation were examined. Inactivation of XET occurred in the foam, but could be decreased significantly by using an efficient antifoam. Rich medium (yeast extract plus peptone) was needed for product accumulation, but not for growth. The proteolytic degradation of the enzyme in the medium was substantially decreased by also adding yeast extract and peptone to the glycerol medium before induction with methanol. Decreasing the fermentation pH from 5.0 to 4.0 further reduced the proteolysis. The specific activity was further improved by production at 15°C instead of 22°C. In this way a XET production of 54 mg/L active enzyme could be achieved in the process with a specific activity of 18 Unit/mg protein after a downstream process including centrifugation, micro- and ultrafiltration, and ion exchange chromatography.

Keywords: Pichia pastoris; xyloglucan endotransglycosylase; foaming; proteolysis

Document Type: Research article

DOI: http://dx.doi.org/10.1007/s12010-005-0006-4

Affiliations: 1: Department of Biotechnology, Royal Institute of Technology, KTH, Alba Nova University Center, Roslagstullsbacken 21, S-106 91, Stockholm, Sweden, 2: Department of Biotechnology, Royal Institute of Technology, KTH, Alba Nova University Center, Roslagstullsbacken 21, S-106 91, Stockholm, Sweden, Email: enfors@biotech.kth.se

Publication date: 2005-02-01

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• In this Subject: Anatomy & Physiology ,  Biotechnology ,  Organic Chemistry ,  Biochemistry
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