Enhanced endoxylanase production by Myceliophthora thermophila with applicability in saccharification of agricultural substrates
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Date
2019
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
3 Biotech
Abstract
The production of enzymes by solid-state fermentation is an interesting process and currently used worldwide as it can
be carried out in solid matrix in absence of free water. In present study, Myceliophthora thermophila BJTLRMDU3 produced
high titres of endoxylanase (890.55 U/g DR, dry residue) using 5 g rice straw at pH 7.0 and at 45 °C with 1:7 (w/v)
solid-to-moisture ratio with inoculum rate of 12 × 106 spores/ml after 4 days in solid-state fermentation. High enzyme
titre was produced after moistening the rice straw with solution containing ammonium sulphate (0.4%), K2HPO4
(1.0%),
MgSO4
·7H2O (0.3%), FeSO4
·7H2O (0.03%) and CaCl2
(0.03%). Addition of sucrose (2% w/v) and ammonium nitrate
(2% w/v) further enhanced the endoxylanase production. A high endoxylanase production was achieved at water activity
(aW) of 0.95 (1639.80 U/g DR) that declined drastically below this value. Among different surfactants, Tween 20 (3% v/v)
enhanced the secretion of endoxylanase (2047.91 U/g DR). Furthermore, on optimization of K2HPO4
concentration, it was
found that 0.5% K2HPO4
improved (2191.28 U/g DR) endoxylanase production and overall 4.35-folds increase in production
of endoxylanase was achieved after optimization of culture conditions. The enzyme has potential to liberate monomeric
(xylose) as well as oligomeric (xylotiose, xylotetrose, and xylopantose) sugars from xylan. On saccharification of rice straw
and corncob with endoxylanase, maximum yield of reducing sugars was 135.61 and 132.61 mg/g of substrate recorded after
48, and 36 h, respectively.
Description
Keywords
Endoxylanase · Myceliophthora thermophila · Rice straw · Solid-state fermentation · Xylooligosaccharides · Saccharification