Effect of overexpression of Saccharomyces cerevisiae Pad1p on the resistance to phenylacrylic acids and lignocellulose hydrolysates under aerobic andoxygen-limited conditions

Citation
S. Larsson et al., Effect of overexpression of Saccharomyces cerevisiae Pad1p on the resistance to phenylacrylic acids and lignocellulose hydrolysates under aerobic andoxygen-limited conditions, APPL MICR B, 57(1-2), 2001, pp. 167-174
Citations number
36
Categorie Soggetti
Biotecnology & Applied Microbiology",Microbiology
Journal title
APPLIED MICROBIOLOGY AND BIOTECHNOLOGY
ISSN journal
01757598 → ACNP
Volume
57
Issue
1-2
Year of publication
2001
Pages
167 - 174
Database
ISI
SICI code
0175-7598(200110)57:1-2<167:EOOOSC>2.0.ZU;2-C
Abstract
Lignocellulose hydrolysates, obtained by acid hydrolysis for production of bioethanol, contain, in addition to fermentable sugars, compounds that inhi bit the fermenting micro-organism. One approach to alleviate the inhibition problem is to use genetic engineering to introduce increased tolerance. Ph enylacrylic acid decarboxylase (Pad1p) catalyses a decarboxylation step, by which aromatic carboxylic acids are converted to the corresponding vinyl d erivatives. Pad1p-overexpressing Saccharomyces cerevisiae was cultivated in synthetic medium in the presence of model compounds, ferulic acid [(2 E)-3 -(4-hydroxy-3-methoxyphenyl)prop-2-enoic acid] and cinnamic acid [(2 E)-3-p henylprop-2-enoic acid], as well as in a dilute acid hydrolysate of spruce to examine the resistance against fermentation inhibitors. Overexpression o f S. cerevisiae phenylacrylic acid decarboxylase (Pad1p) resulted in an imp roved growth rate and ethanol productivity in the presence of ferulic acid, cinnamic acid, and in a dilute acid hydrolysate of spruce. Vinyl guaiacol (2-methoxy-4-vinylphenol) was identified as a major metabolite of ferulic a cid, and dihydroferulic acid [3-(4-hydroxy-3-methoxyphenyl)propanoic acid] was detected under oxygen-limited conditions. Styrene (vinylbenzene) and di hydrocinnamic acid (3-phenylpropanoic acid) were identified as metabolites of cinnamic acid. Transformants overexpressing Pad1p had the ability to con vert ferulic and cinnamic acid at a faster rate than a control transformant (PAD(C)) not overexpressing Pad1p. This enabled faster growth for Pad1p-ov erexpressing transformants under both aerobic and oxygen-limited conditions . Pad1p activity was also studied using nongrowing cells. The overexpressin g transformants showed approximately tenfold higher activity than PADc. The Pad1p overexpressing transformants also showed a 22-25% faster glucose con sumption rate, a 40-45% faster mannose consumption rate, and a 24-29% faste r ethanol production rate in the dilute acid hydrolysate of spruce.