Speaker at Pharma Virtual 2020 2020 - Victor Alfonso Alonso-Campos
Department of Environmental Sciences, IPICYT, San Luis Potosi, San Luis Potosi, Mexico
Title : Biotechnological approach to valorize emissions: Biological conversion of styrene to polyhydroxyalkanoates using two-phase partitioning bioreactors


Styrene is an important pollutant released from chemical industry. Manufacturing of reinforced plastic, synthetic rubber and resin is the main source of styrene to atmosphere. These industrial activities consume about 15 million tons per year of styrene. In the best of scenarios, styrene emissions are recycled in 60 % and released to atmosphere in 20 %. However, in Mexico, all styrene emissions are released to atmosphere due to lack in emissions legislation. In order to promote sustainable processes to treat emissions from industrial sources in Mexico, this research work is focused to valorize styrene emissions using biotechnological processes to produce high added value products. To achieve this, the use of two-phase partitioning bioreactors (TPPB) which combine aqueous medium with a hydrophobic non-aqueous phase liquid (NAPL) is proposed. Firstly, the NAPL will increase the solubility of styrene into liquid medium because styrene is hydrophobic. Secondly, the use of  NAPL  will  avoid  the  inhibition  of  styrene  to  microorganisms  which  can  be  toxic  at  high  concentrations.  Thus,  NAPL  will work  as a  mass  transfer  vector  of  styrene  from  gaseous  to liquid  medium  and  as  a reservoir which will  reduce  the risk of  styrene inhibition  to  microorganisms.  This  strategy  has  been  successful  in  the  biodegradation  of  hydrophobic  gaseous  pollutants, but, TPPB has not been proved in the conversion of this type of pollutants to biopolymers. In order to test the assumptions detailed, two NAPL such as silicon oil and ionic liquids and the strain Pseudomonas putida S12 were chosen. P. putida S12 has been reported to consume styrene and produce polyhydroxyalkanoates (PHAs, a high added value biopolymer). After caring out affinity to target  compound, biodegradability and toxicity tests to  choose the best  NAPL to consume  styrene and  produce PHAs, it was found that ionic liquid absorbed 7.5 times more styrene than silicon oil (Hsty/IL = 0.0030; Hsty/SO = 0.0226; 28 °C) and both silicon oil and ionic liquid were non-biodegradable by P. putida S12 . However, the  ionic  liquid caused inhibition to P. putida S12 in contrast to silicon oil which was not toxic for the strain. Then, it was concluded that silicon oil is the best NAPL for the TPPB experiments. Kinetic experiments were performed with and without NAPL to know if the addition of this increases the rate to produce the biopolymer. Results show that styrene removal rate and production rate of biopolymer in the presence of silicon oil were two times greater than control experiments in one phase (without silicon oil). Finally, the use of TPPB is a good alternative to valorize emissions of hydrophobic gaseous pollutants like styrene to produce high valuable products such as PHAs. However, investigations of this technology to show its viability in large scale are need.


Mr. Víctor Alonso studied Environmental Biochemistry Engineering at the Autonomous University of Campeche, Mexico. During Bachelor studies, He studied the sequestration of carbon in mangroves. Currently, He is studying a master´s degree in Environmental Sciences at IPICYT, Mexico. He is learning about treatment and valorization of gaseous effluents using biotechnological processes.