Recent Advances in The Study of Biodegradability of Polyvinyl Alcohol (PVA) (Ⅲ)

3. The study of PVA biodegradation mechanism

There are three main types of PVA degrading enzymes, namely PVA oxidase, PVA dehydrogenase, and oxidative PVA hydrolase. The catalytic reaction mechanism of these three types of enzymes will be explored below.

The degradation of PVA by enzymes is a complex process, and its mechanism has different views among different scholars, but the current consensus is that the degradation of PVA can only be degraded through two enzymatic steps, in which the first step refers to PVA oxidase using oxygen as the electron acceptor, or PVA dehydrogenase using PQQ as the electron acceptor to dehydrogenate and oxidize PVA to ketone based compounds. One is that PVA is oxidized to oxidized PVA by PVA oxidase or PVA dehydrogenase, and then cleaved by oxidized PVA hydrolase. Another view is that the oxidative PVA hydrolysis reaction is a spontaneous reaction, and its hydrolysis is mainly due to the instability of the molecular structure itself and spontaneous hydrolysis. The oxidative PVA hydrolase only accelerates the cleavage reaction.

In the process of studying the degradation mechanism, in order to prevent the products from being too complicated for analysis, researchers usually use some simple compounds with structures similar to PVA to simulate the degradation process of PVA, so the actual degradation process, whether the base degradation steps are as presumed by the researchers is uncertain and needs to be further verified.

At present, the results of research on the biodegradation of polyvinyl alcohol show that PVA degrading bacteria are difficult to extract in nature because they are not widely available in nature. Even if the extracted PVA degrading bacteria are able to degrade PVA, the degradation efficiency of PVA is also very low, and with the existing technology, it is still not possible to completely degrade PVA after a long time of culture and domestication. research on the biodegradation mechanism of PVA will be beneficial to the screening of efficient PVA degrading bacteria to achieve complete biodegradation of PVA.