Exploitation of Agricultural Wastes and By-Products for Production of Aureobasidium pullulans Y-2311-1 Xylanase: Screening, Bioprocess Optimization and Scale Up

Abstract

The potential of several agricultural wastes and by-products (wheat bran, oat bran, corn cob, brewer's spent grain, malt sprout, artichoke stem, sugar beet pulp, olive seed, cotton stalk and hazelnut skin) was examined as the substrate for xylanase production by Aureobasidium pullulans Y-2311-1. Based on the screening studies, wheat bran was selected as the best substrate for further optimization studies. The effects of initial medium pH, temperature and incubation time on xylanase production in shake flask system were optimized by response surface methodology (RSM). The optimum levels of the process variables defined by the model (initial medium pH, 4.24; temperature, 30.27°C; and incubation time 126.67 h) resulted in production of 85.19 U/ml xylanase. Taking the RSM optimized parameters in shake-flask scale into consideration; xylanase production was scaled up to bioreactor system with a working volume of 1.5 l. The peak of enzyme production was achieved after 126 h incubation that has previously been determined by RSM studies at shake flask level. Furthermore, the optimum levels of agitation and aeration in bioreactor system was found as 200 rpm and 1.5 vvm. Maximum enzyme production was close to 85 kU/l which could be translated into a productivity of 0.68 kU/l/h. No previous work considered the statistical optimization of xylanase production by A. pullulans on wheat bran and scale up of the bioprocess to a bioreactor system.

Exploitation of Parthenium hysterophorous biomass as low-cost substrate for cellulase and xylanase production under solid-state fermentation using Talaromyces stipitatus MTCC 12687

“…Therefore, the main focus of recent researches is to develop an economic process for enzyme production. Substrate cost has been estimated more than 30% of total enzyme production expenses during fermentation process (Yegin, Oguz, Sayit, & Yekta, 2016). Use of agriculture residues, food industrial waste, fruit waste, vegetable waste and weed plants as a low-cost solid substrate for the production of cellulases and xylanases have potential to overcome this problem (Barnabe & Barnabe, 2015Chugh, Soni, & Soni, 2016;Dwivedi, Vivekanand, Ganguly, & Singh, 2009).…”

Malt sprout, an underused beer by-product with promising potential for the growth and dehydration of lactobacilli strains

“…In this regard, whey, whey permeate, okara and several other agro-wastes have been proposed as alternative culture media for lactic acid bacteria production (Golowczyc et al 2013;Londero et al 2012Londero et al , 2014Londero et al , 2015Quintana et al 2017). Malt sprout also fulfills these desired requirements, and thus, it has been used in the past to grow Rhizobium species (Bioardi and Ertola 1985) or more recently added as nitrogen source in other culture media (Liu et al 2010;Yegin et al 2017). Regarding lactic acid bacteria, malt sprout itself has been proposed as an efficient culture medium for large-scale production of lactobacilli, with similar results to those obtained in MRS medium (Laitila et al 2004).…”

Optimization of saccharification potential of recombinant xylanase from Bacillus licheniformis

“… 18 For maximum xylanase production from Aureobasidium pullulans 200 rpm agitation rate and 1.5 vvm aeration rate has been reported. 19 In another study, the maximum xylanase enzyme production was achieved from Bacillus altitudinis in a 7.5 L stirred tank fermenter with 12.5% inoculum size when the agitation and aeration rates were 200 rpm and 1.00 vvm, respectively. 20

Figure 3.

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