Polyhydroxybutyrate production using a wastewater microalgae based media Asif Rahman a , Ryan J. Putman a , Kadriye Inan b , Fulya Ay Sal c , Ashik Sathish a , Terence Smith a , Chad Nielsen a , Ronald C. Sims a , Charles D. Miller a, ⁎ a Department of Biological Engineering, Utah State University, 4105 Old Main Hill, Logan, UT 84322–4105, United States b Department of Molecular Biology and Genetics, Karadeniz Technical University, Trabzon, Turkey c Department of Biology, Karadeniz Technical University, Trabzon, Turkey abstract article info Article history: Received 11 September 2014 Received in revised form 9 December 2014 Accepted 20 January 2015 Available online xxxx Keywords: Wastewater Microalgae Bioproduct Polyhydroxybutyrate Bioproduct production from wastewater microalgae has the potential to contribute to societal needs with value added chemicals. Microalgae can remediate wastewater to remove nitrogen, phosphorus, and heavy metals and can be processed to produce biofuels and bioproducts. It was previously demonstrated that recombinant Escherichia coli could produce polyhydroxybutyrates (PHBs) when cultured on a wastewater microalgae wet lipid extracted media. In this present study, microalgae were harvested from the effluent of a wastewater treat- ment facility via centrifugation and hydrolyzed to create a liquid medium for recombinant E. coli growth and PHB production. Standard E. coli growth media was supplemented with various concentrations of hydrolyzed algal extract to produce a maximum of 31% PHB of the E. coli dry cell weight. © 2015 Elsevier B.V. All rights reserved. 1. Introduction Microalgae have been well studied for production of biodiesel [1] and recently microalgae have been proposed to be the basis for a biorefinery model where multiple chemicals can be produced simulta- neously [2]. Producing several chemicals from the same microalgae feedstock could potentially make the production of multiple commodity chemicals from a biological resource economically viable. The limita- tions to microalgae culturing are well-documented, including but not limited to: nutrient supply, water scarcity, harvesting, and dewatering [3]. The City of Logan, UT has a 460 acre seven pond facultative lagoon system to treat weak domestic wastewater. Weak domestic wastewater contains approximately 20 mg/L nitrogen and 4 mg/L phosphorus, and is ideal for microalgae growth [4]. Facultative lagoon systems can be used to culture mixed consortia of microalgae to remediate the waste- water by removal of phosphorus and nitrogen. There are a wide range of methods previously employed to harvest microalgae from an open pond system that include: rotating algal biofilm reactor (RABR) [5,6], biological and chemical flocculants [2,7,8], and centrifugation [9]. Harvested microalgae can then be processed and used as a feedstock for production of bioproducts [10,11]. It has been demonstrated that Escherichia coli can be cultured on microalgae based substrates for pro- duction of biofuels and bioplastics [12,13] E. coli can be easily cultured and has a fast doubling time making it an ideal candidate for production of recombinant bioproducts. Polyhydroxybutyrates (PHBs) are bioplastics that can be recombinantly produced in E. coli [14] and cyanobacteria [15]. PHB is a potentially use- ful polymer, in addition to being completely biodegradable, it has simi- lar properties to traditional petrochemically derived plastics such as polypropylene and polystyrene [16]. Three genes are needed for the conversion of acetyl-CoA to PHB in E. coli. The pBHR68 plasmid contains the lac promoter and three genes (phaA, phaB, and phaC) needed for production of the short chain length (scl) polymer PHB [17]. Bacterial PHB production is not widespread in part due to the cost of the carbon substrate. It has been estimated that the carbon substrate in a large scale manufacturing context would constitute approximately 37% of the total production cost [18]. Due to the high cost of carbon, an alternative low cost substitute is needed to culture E. coli in order to make PHB production economically viable. In a previous study, it was demonstrated that E. coli harboring the pBHR68 plasmid was able to successfully grow on a Scenedesmus obliquus microalgae based media [2]. In a different study, various harvesting methods were used to collect microalgae grown in photobioreactors [19] and then the har- vested microalgae was processed via the wet lipid extraction procedure (WLEP) to generate a variety of side streams and bioproducts [2,20]. One of the side streams, termed ‘aqueous phase’ was used to culture E. coli and it was established that the upstream harvesting method of S. obliquus affected the growth of the E. coli in the aqueous phase media. The most successful microalgae harvesting method for high levels of E. coli growth after 48 h (10 12 –10 13 CFU/mL) was observed Algal Research 8 (2015) 95–98 ⁎ Corresponding author. E-mail address: charles.miller@usu.edu (C.D. Miller). http://dx.doi.org/10.1016/j.algal.2015.01.009 2211-9264/© 2015 Elsevier B.V. All rights reserved. Contents lists available at ScienceDirect Algal Research journal homepage: www.elsevier.com/locate/algal