ENHANCED PRODUCTION OF POLYHYDROXYBUTYRATE (PHB) FROM AGRO-INDUSTRIAL WASTES; FED-BATCH CULTIVATION AND STATISTICAL MEDIA OPTIMIZATION

Mahmoud M Berekaa,Adil M Al Issa

doi:10.15414/jmbfs.2016.5.6.606-611

Mahmoud M Berekaa, Adil M Al Issa

Open Access

https://doi.org/10.15414/jmbfs.2016.5.6.606-611

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Abstract

Bacillus megaterium SW1-2 showed enhanced growth and polyhydroxybutyrate (PHB) production during cultivation on date palm syrup (DEPS) or sugar cane molasses. FT-IR and NMR spectroscopic analyses of the polymer accumulated during growth on DEPS revealed specific absorption peaks characteristic for PHB. 1.65 g/L of PHB (56.9% CDW) was produced during growth on medium supplemented with 2 g/L of DEPS. Approximately, 36.1% CDW of PHB were recorded during growth on sugar cane molasses. Six runs of different fed-batch cultivation strategies were tested, the optimal run showed approximately 6.87-fold increase. Modified E2 medium was prefered recording 10.11 and 11.34 g/L of total PHB produced for runs 1 and 2, at the end of 96 h incubation period, respectively. Decrease in PHB was recorded during growth on complex medium (run 3 and run 4). In another independent optimization strategy, ten variables were concurrently examined for their significance on PHB production by Plackett-Burman statistical design for the first time. Among variables, DEPS-II and inoculum concentration followed by KH2PO4 and (NH4)2SO4 were found to be the most significant variables encourage PHB production. Indeed, DEPS-II or Fresh syrup is more significant than commercial syrup DEPS-I (p-value= 0.05). RPM, incubation period have highly negative effect on PHB production. Role of ago-industrial wastes, especially DEPS, in enhancement of PHB production was closely discussed.

Highlights

Among the most commonly known biopolymers, bacterial polyhydroxyalkanoates (PHAs) polyesters gain more interest
Growth of Bacillus megaterium SW1-2 on date syrup (DEPS) Among a group of polyhydroxybutyrate-producing bacilli explored for potential production of PHB biopolymer from an agro-industrial waste namely; date palm syrup (DEPS), Bacillus megaterium SW1-2 showed potent growth on DEPS or date syrup as a sole source of carbon
For economic visibility of PHB biopolymer production by B. megaterium SW1-2 date syrup or DEPS was used as a natural carbon source

Summary

Introduction

Among the most commonly known biopolymers, bacterial polyhydroxyalkanoates (PHAs) polyesters gain more interest. Application of statistical methods has gained a lot of impetus for medium optimization and understanding the interactions among various physiochemical parameters involved in biopolymer production (Khanna and Srivastava, 2005; Nikel et al, 2005; Sharma et al, 2007; Mokhtari-Hosseini et al, 2009; Pandian et al, 2010; Berekaa and Al Thawadi., 2012; Hamieh et al, 2013). Optimization of PHB production by application of six different fed-batch cultivation strategies was closely investigated. Special emphasis was given to the application of statistical experimental design (Plackett-Burman) for optimization of PHB production from DEPS for the first time

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