Philippine Journal of Science
152 (1): 381-395, February 2023
ISSN 0031 – 7683
Date Received: 15 Jun 2022

Pretreatment Optimization of Corn Stover
with Subsequent Enzymatic Hydrolysis
for Polyhydroxybutyrate (PHB) Production

Nika Anna D. Perez1, Princess J. Requiso2, Catalino G. Alfafara1,
Jewel A. Capunitan1, Fidel Rey P. Nayve Jr.3, and Jey-R S. Ventura4*

1Department of Chemical Engineering, College of Engineering and Agro-Industrial Technology,
University of the Philippines Los Baños (UPLB) Los Baños,
College, Los Baños, Laguna 4031 Philippines
2UP College of Medicine, University of the Philippines Manila,
Taft Avenue, Ermita, Manila 1000 Philippines
3National Institute of Molecular Biology and Biotechnology,
University of the Philippines Los Baños, College, Los Baños, Laguna 4031 Philippines
4Biomaterials and Environmental Engineering Laboratory,
Department of Engineering Science, College of Engineering and Agro-Industrial Technology,
University of the Philippines Los Baños, Los Baños, College, Los Baños, Laguna 4031 Philippines

*Corresponding author: jsventura@up.edu.ph

[Download]
Perez NA et al. 2023. Pretreatment Optimization of Corn Stover with Subsequent Enzymatic
Hydrolysis for Polyhydroxybutyrate (PHB) Production. Philipp J Sci 152(1): 381–395.
https://doi.org/10.56899/152.01.30

 

 

ABSTRACT

Polyhydroxybutyrate (PHB) is considered a potential substitute for conventional, non-biodegradable petroleum-based plastics. However, high production cost has been a major drawback to the commercialization of PHB. The use of low-cost lignocellulosic agricultural residues such as corn stover, together with an effective pretreatment method, can reduce production costs. In this study, optimization of pretreatment methods for corn stover – namely, steam explosion and sequential steam explosion–dilute acid pretreatment – was done to maximize the concentration of reducing sugars in the hydrolysate obtained after enzymatic saccharification. Response surface methodology (RSM)-designed experiments showed that steam explosion temperature had the highest impact on reducing sugar production for both pretreatment methods. Optimum conditions for steam explosion pretreatment were 220.9 °C steam explosion temperature and 11.2 min residence time, yielding a hydrolysate with 9.67 g/L (64.50% yield) of reducing sugars after saccharification. For the sequential pretreatment, 9.14 g/L of reducing sugars (60.93% yield) was produced from the optimum conditions of 224.8 °C steam explosion temperature, 144.2 °C dilute acid temperature, 43.8 min reaction time, and 5% w/v acid concentration. Dilute acid pretreatment significantly decreased the reducing sugar yield after the steam explosion by 5.5%, probably due to the degradation of reducing sugars, making steam explosion sufficient in the pretreatment of corn stover. More importantly, PHB was produced using the hydrolysate from steam-exploded corn stover, with a maximum concentration of 1.81 g/L after 24 h of bacterial fermentation. Therefore, the steam explosion was proven effective in producing sugar-rich hydrolysates from corn stover for PHB production.