Polyhydroxyalkanoate Production by &amp;lt;i&amp;gt;Pseudomonas putida&amp;lt;/i&amp;gt; KT217 on a Condensed Corn Solubles Based Medium Fed with Glycerol Water or Sunflower Soapstock

Jeremy Javers,Chinnadurai Karunanithy

doi:10.4236/aim.2012.23029

Abstract

Pseudomonas putida KT217 was grown on a complex medium comprised of co-products of the ethanol and biodiesel industries to assess the organism's capability to produce medium-chain-length polyhydroxyalkanoate (mcl-PHA). The growth phase was carried out in a medium containing 400 g/L condensed corn solubles (CCS), supplemented with ammonium hydroxide as a nitrogen source. Following the exponential phase, co-products of the biodiesel industry (soapstock and glycerin) were fed into the reactor to trigger PHA production. When glycerin was added to the bioreactor (75 g/L total addition), the final cell dry weight (CDW) and PHA content were 30 g/L and 31%, respectively. The monomeric composition in the PHA formed was relatively uniform throughout incubation with 3-hydroxydecanoate dominating. When a total of 153 g/L of sunflower soapstock was added to the bioreactor in a fed-batch manner, the final CDW and PHA content were 17 g/L and 17%, respectively. Following addition of soapstock the monomeric composition of the polymer changed dramatically, with the 3-hydroxyoctanoate monomer becoming dominant and greater unsaturation present in the PHA.

Highlights

Polyhydroxyalkanoates (PHAs) are a class of biodegradable polymers that have a wide range of physical properties depending upon the monomeric composition in the polymer [1,2,3,4]
P. putida KT217 was grown in an aerated bioreactor on a 400 g/L condensed corn solubles (CCS)-based medium supplemented with 2.2 g/L ammonium hydroxide
PHA production was observed over 100 h of aerated incubation when P. putida KT217 was grown on a basal medium of 400 g/L CCS and 2.2 g/L ammonium hydroxide, supplemented in fed-batch mode with either biodiesel co-products glycerol water (240 g) or soapstock (390 g)

Summary

Introduction

Polyhydroxyalkanoates (PHAs) are a class of biodegradable polymers that have a wide range of physical properties depending upon the monomeric composition in the polymer [1,2,3,4]. With recent breakthroughs in PHA production technology and soaring oil prices, PHA and other biopolymers may be at the front of true commercial integration [5]. Biopolymers such as 1 3 propanediol, polylactic acid, starch based polymers, and PHA could capture as much as 1.5% - 4.8% of the total plastics market (~260 million tonnes/year). Several low cost substrates have been evaluated for PHA production, but low productivities typically result [14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29,30]. The ethanol and biodiesel production industries generate large quantities of under-utilized byproducts which could be used for PHA production

Methods

Results

Conclusion