Identifying inhibitory compounds in lignocellulosic biomass hydrolysates using an exometabolomics approach

BMC Biotechnology

Table 5 Inhibitory effects of the compounds identified by lag-phase, Glu CR and EtOH PR models, tested using Bioscreen C Analyzer

Reference medium (MM with 20 g/l glucose)					LP	GR	OD
Reference medium (MM with 20 g/l glucose)					7 h	0.105	1.2
Compounds	Structure	0.2 g/l			0.5 g/l			1.0 g/l
Compounds	Structure	LP	GR	OD	LP	GR	OD	LP	GR	OD
Compounds identified by all 3 phenotype models
Furfural		10 h	---	---	15 h	---	---	30 h	No growth
HMF		---	---	---	---	---	---	---	< 20%	---
Sorbic acid		---	< 60%	< 80%	---	< 60%	< 80%	No growth
Syringaldehyde		---	---	---	---	---	---	---	< 60%	< 80%
Suberic acid								3 h	110%	110%
Compounds identified by lag-phase model
Benzoic acid		---	< 60%	< 80%	---	< 40%	< 80%	---	< 40%	< 60%
Compounds identified by Glu CR and EtOH PR models
Phenylacet aldehyde		20 h	< 80%	---	No growth			No growth
Vanillin		---	---	---	11 h	< 80%	---	30 h	No growth
4-hydroxybenzaldehyde		---	---	---	9.5 h	< 80%	---	11 h	< 60%	< 80%
Dihydroxy benzene		---	---	---	---	---	---	---	< 80%	---
Conifer aldehyde		---	---	---	23 h	---	---	No growth
Compounds identified by Glu CR model
Ferulic acid		---	---	---	---	---	---	---	< 40%	< 80%
Benzaldehyde		---	---	---	9.5 h	< 80%	---	13.5 h	< 80%	< 80%
Compounds identified by EtOH PR model
Salicylic acid		---	< 80%	< 80%	---	< 60%	< 80%	---	< 60%	< 60%
No effect
2-furoic acid		Pantolactone				Levulinic acid
Furfuryl alcohol		2-furanmethanol acetate				HMF alcohol
P-coumaric acid		Homovanillic acid				HMF acid
3-phenyllactic acid		4-hydroxybenzoic acid				Vanillic acid
Not tested
4-Hydroxyphenylaldehyde		Phloretic acid				5-HMF methyl keton

LP: lag-phase: time needed to reach 2% (ODmax-ODmin) (h), GR: growth rate: the slope of the linear part of the OD curve (OD/h), OD: final OD. Values with% are relative growth rate and final OD compared to that in reference medium. ‘---’: no effect compared to reference medium.
The compounds indicated in ‘italic’ were originally identified by their (converted and less toxic) alcohol forms; the compounds indicated in ‘bold’ were saturated when 1 g/l solutions were prepared at the fermentation temperature, in these cases, besides the saturated solution, a 2- and 5- fold dilution was used, represented in the 0.5 and 0.2 g/l columns, respectively; the ‘italic effects’ were NOT observed when tested in YPD medium.

ISSN: 1472-6750