September, 27, 2011 - Sustainable chemical processes that minimize the generation of residues and can be incorporated into the production of biodegradable plastics. With this in mind, researchers at the Industrial Microbiology Laboratory of the Biosciences Institute of the São Paulo State University (UNESP) in Rio Claro are conducting a study involving the production and extraction of lactic acid through the fermentation of residues from renewable resources, leading to a polymeric synthesis for the production of a polylactic acid (PLA). This material can be used to produce bioplastics and can be applied to various products, including food, drug and cosmetics packaging, as well as capsules for medicine and orthopedic implants in the biomedical industry.
The research project Study on the recovery and purification of lactic acid from a growth medium produced by isolated microorganisms for the production of biodegradable plastics, part of FAPESP’s Partnership for Technological Innovation Program (PITE), has been selected from a series of proposals arising from the FAPESP-Braskem/Ideom Cooperation Agreement, which targets the development of material with physical and chemical characteristics similar to those of petroleum byproducts, but causing substantially less harm to the environment. According to Jonas Contiero, a professor at UNESP’s Institute of Biosciences in Rio Claro and coordinator of the program, this is a highly complex study of a still costly process to recover and purify lactic acid. In order to reduce these costs, Contiero is attempting to increase production of the substance by using alternative nitrogen and carbon sources, in this case substrates generated by the sugar and ethanol industry and cheese production.

Although PLA’s resistance and crystallinity mean that it can also be used to produce fibers and films, the production process should maintain the compound’s biodegradability. According to Contiero, this process is cheaper than those currently being developed in the United States and Belgium, which obtain polylactate from corn starch and beet sugar, respectively, so commercial production could well be feasible. In addition, "the amount of lignocellulosic fibers in sugarcane industry residues or byproducts, i.e. bagasse and straw, give them a unique competitive advantage compared with other carbon sources, since these residues can also be used to generate energy for the operation of the production plant," explained the researcher.

Research and use

The project is a continuation of the research project Isolation and selection of microorganisms and the development of technology for the production of lactic acid, also supported by FAPESP, which selected potential microorganisms that produce one of the lactic acid isomers and improved the production parameters, with the beginning of extraction, purification and polymerization.

The level of purity necessary for the use of PLA depends on its application. For instance, for medical purposes, the material must provide maximum residual specifications of humidity, solvents, tin content and monomer specifications, among others. After the production of the polymer, chemical analyses are undertaken to ascertain the presence of these residues and determine the degree of purity, ensuring the final quality of the material and its use in the manufacturing industry.