Fermentative l-lactic acid production from pretreated whole slurry of oil palm trunk treated by hydrothermolysis and subsequent enzymatic hydrolysis

Published Date
Bioresource Technology
June 2015, Vol.185:143–149, doi:10.1016/j.biortech.2015.02.060

• Author 

• In-Yong Eom ^a,1
• Young-Hoon Oh ^a,1
• Si Jae Park ^b
• Seung-Hwan Lee ^c
• Ju-Hyun Yu ^a,,

• aCenter for Bio-based Chemistry, Green Chemistry & Engineering Division, Korea Research Institute of Chemical Technology, P.O. Box 107, 141 Gajeong-ro, Yuseong-gu, Daejeon 305-600, Republic of Korea
• bDepartment of Environmental Engineering and Energy, Myongji University, 116 Myongji-ro, Cheoin-gu, Yongin, Gyeonggido 449-728, Republic of Korea
• cDepartment of Biotechnology and Bioengineering, Chonnam National University, 77 Yongbong-ro, Buk-gu, Gwangju 500-757, Republic of Korea

Received 13 January 2015. Revised 12 February 2015. Accepted 13 February 2015. Available online 26 February 2015. 

Highlights

• •
  Lactic acid conversion process was designed to minimize starch loss of oil palm trunk.
• •
  Oil palm trunk was subjected to autohydrolysis.
• •
  Pretreated whole slurry was enzymatically hydrolyzed and fermented by a Lactobacillus.
• •
  l-Lactic acid yield reached to 89.5% of the theoretical lactic acid yield.

Abstract

A simple and cost-effective biochemical conversion process consisting of hydrothermal treatment, enzymatic hydrolysis and fermentation of pretreated whole slurry (PWS) was developed for producing l-lactic acid (L-LA) from oil palm trunk (OPT). When OPT was hydrothermally treated at optimal condition capable of achieving maximum yield of hemicellulosic sugars after enzymatic hydrolysis, the enzymatic digestibility of the PWS afforded a yield of 81.4% of the theoretical glucose yield (TGY). However, glucose yield from washed pretreated solid (WPS) was only 43.5% of TGY. The use of two hydrolysates from PWS and WPS for fermentation by Lactobacillus paracasei engineered to selectively produce L-LA afforded yields of 89.5% and 45.8% of the theoretical LA yield (TLY), respectively. This study confirmed the inevitable extensive sugar loss during washing of pretreated slurry due to loss of soluble starch. Alternatively, the proposed design process is considered suitable for converting OPT to L-LA without such starch loss.

Abbreviations

PWS, pretreated whole slurry

LA, lactic acid

OPT, oil palm trunk

TGY, theoretical glucose yield

WPS, washed pretreated solid

TLY, theoretical LA yield

L. paracasei, Lactobacillus paracasei

NREL, National Renewable Energy Laboratory

HPLC, high performance liquid chromatography

XGM, the sum of xylose, galactose and mannose

Furfural, 2-furaldehyde

HMF, 5-hydroxymethyl-2-furaldehyde

PA, parenchyma

VB, vascular bundle

TEY, theoretical ethanol yield

Keywords

Oil palm trunk

Starch

Hydrothermal treatment

Lactobacillus paracasei

l-Lactic acid

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• ⁎ 
  Corresponding author. Tel.: +82 42 860 7438; fax: +82 42 860 7049.

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