Transgenic mammalian salivary cells expressing ligninase as a proof-of-concept model for enhanced lignocellulose degradation to generate future resilient livestock

The major limitation in feed grade utility of cereal straws is the presence of the high amount of lignified fiber. Considering the limited ligninase availability in rumen, the current work is intended to establish the proof-of-concept for a recombinant ligninase expression in mammalian salivary gland cells so that it can be translated into generation of a live transgenic ruminant that can produce ligninase in its saliva for enhanced degradation of lignin. To verify the proof of concept the Sleeping Beauty transposon vector (pT2-RMCE) containing a ubiquitously active CAGGS promoter was used to express three different types of bacterial ligninases. Two of them are dye decolorizing peroxidase family (DyP1 and Dyp2) which belong to the category of heme peroxidases and one is laccase which belongs to a multi-copper oxidase (cotA). The vector was transfected into rat ParC10 salivary cell lines and the protein expressed by the engineered cells was harvested, purified to check the functionality on Kraft lignin degradation. Among the three, only DyP1 could be detected on Western blot and was also found to be functionally active. It can be concluded that mammalian salivary cells can be genetically engineered with appropriate ligninase gene to produce functional ligninase.