The investigation of ligninolytic enzyme activity variations depend on growth conditions

Lignin degradation by fungi and their specific enzymes has been focus of a large number of biotechnological studies. The most efficient lignin degraders are fungi of the white rot group. Of these, Pleurotus eryngii is commercially important edible mushroom species. This fungus can be cultivated in synthetic medium. Therefore, there has been an increasing trend to ligninolytic enzymes in recent years.In this study; the aim is to investigate optimal growth conditions for maximum ligninolytic enzyme activities, which are laccase (Lac), manganese peroxidase (MnP), lignin peroxidase (LiP) and aryl alcohol oxidase (AAO) enzymes from P. eryngii in submerged fermentation (SF). In addition, reducing sugar, nitrogen and protein levels, biomass and pH levels were also researched. For this purpose, the effects of basal medium and flask volume, different liquid medium, inoculation type and temperature, cultivation mode, nitrate, manganese and copper concentrations were studied for SF conditions. In SF, cultivation was performed with plug inoculation and stationary incubation at degree of 28.According to the results, the highest Lac and MnP activities were detected as 973.333 and 756 U/L, while LiP and AAO were obtained as 42.527 and 271.828 U/L, respectively. The reducing sugar and nitrogen levels in SF were sharply decreased on the fifth day. Finally, decolorization of methyl orange, reactive red 2 and reactive black 5 was performed with the ligninolytic enzyme obtained by SF. These results showed that the investigated ligninolytic enzymes can be used decolorization of azo dyes.