 Hello everybody, my name is Elena Moralejo and I'm the first author of the paper entitled The Influence of the Cycle Length on the PHA and Polyglucose Production from glycerol by bacterial enrichment in sequencing batch reactors that has been recently published in biotechnology and bioengineering journal. I'm a PhD student working at Delphi University of Technology in the Netherlands and the University of Santiago de Compostela in Spain. Polyderoxial cannoids or PHA are naturally occurring polymers that many bacteria are able to synthesize. During the last years they become very important because of their plastic-like properties so that's why they are known as bioplastics. From the biological point of view they act as a storage of carbon and energy inside the bacteria. Carbon industrial PHA production process is based on the use of pure cultures and pure substrate so that results in a really expensive material that is limited to uses like medicine. What we propose is a low-cost PHA production process. It's based on the use of bacterial enrichment and waste as substrate. The advantages will be to fold. On the one hand we will be avoiding the costs associated to the sterile production and on the other hand since we are using our waste as substrate we will be enhancing the sustainability of the process that generates the waste. The process is based on two steps. The first step consists on selecting the microorganisms that have the ability to produce these storage polymers so we make use of activated sludge and we will apply a selective pressure in the system. The idea is that we are engineering the system instead of engineering the microorganism. This selective pressure is based on the natural role of PHA as carbon and energy reserve so we will dose the feed at certain time intervals and that will result in the so-called feast famine regime. So during the feast phase that's the time when substrate is available the bacteria that has the ability to produce PHA will store the substrate in the form of PHA and then during the period where no substrate is available that's the famine phase the bacteria that has the ability to store PHA will be able to grow using that polymers as carbon and energy reserve. So by repeating this feeding pattern we will wash out the microorganisms that can only grow and we will enrich the system naturally on microorganisms that have the ability to produce PHA. So we will switch from activated sludge to enrichment that is reached on a bacteria that has the ability to produce PHA. Once the bacterial enrichment is selected we will maximize this biopolymer content in the second step that's the accumulation step and we will dose a big amount of carbon source and we will prevent growth by limiting the presence of high essential nutrients that is usually ammonia. So at the end of this fermentation we have this the bacteria that contain up to 80 percent of PHA. So in this picture we can see how do bacteria look like at the end of the famine phase that's when they have consumed all the polymers that they stored in the previous phase as the fist phase and in this picture we can see how they look like when they are full of polymer at the end of the fist phase or at the end of the accumulation experiment and we can see the white inclusions inside the cell that that's the PHA. A special characteristic about the use of glycerol at substrate is that besides PHA we also obtain a polymer of glucose that we will refer to as polyglucose. Based on previous experiences we saw that the kinetics associated to the production and to the consumption of these two polymers were markedly different. So the aim of this study is to test the influence of the enrichment cycle length on the distribution of glycerol among these two polymers. So we will study and compare the performance of two different enrichment reactors. One operates with cycles of six hours so it will have six sorry four cycles per day and the second reactor operates with cycles of 24 hours so we will operate with one cycle per day. As we can see the distribution of glycerol among the two polymers among the PHA that was how PHA was present and polyglucose were different. So you can see the details of this study in the article and I would like to introduce my the co-authors of this paper. On the one hand we have Mark Balnoz-Drexana Robert Trellevesian from the University of Technology and Tanya Palmeiro-Sanchez and Nusca Mosquera Corral and José Luis Campos from the University of Santiago de Compostela. Thank you very much for your attention and I encourage you to read the article since we are presenting a natural mechanism to select from microorganisms with the ability to produce a value added product using waste as substrate. Enjoy your reading.