Determination of bacterial and fungal numbers in floats of pre-tanning operations

Abstract

This study was aimed at determining the numbers of bacteria and fungi in the floats of main soaking, liming, deliming-bating, degreasing and pickling stages. To this end, the numbers of total aerobic
mesophilic, proteolytic, lipolytic and aerobic spore-forming bacteria and, the numbers of total aerobic fungi (yeast and mould), proteolytic and lipolytic fungi were determined on the media containing
different concentration of NaCl (0, 5, 10, 15 and 25%). Sheep skins were processed up to the end of pickling stage by adding a commercial bactericide (Derbio® DB 99), whose active ingredient is composed of quarternized compounds, into main soaking float. According to the results of the study, while most of the bacteria displayed growth from the main soaking process to the end of delimingbating, most of the fungi showed growth from the main soaking process to degreasing. It is found that main soaking and deliming-bating processes came to the fore in terms of bacterial growth. It is also remarkable that the numbers of proteolytic bacteria were higher in degreasing float as well as in main
soaking float. In the study, fungal numbers were found to be lower in all the stages than bacterial numbers in general. Moreover, fungi displayed growth in all NaCl concentrations (0, 5, 10 and 15%) in all the processes up to the end of the degreasing process except on the media containing 25% NaCl for the main soaking float. As for in pickling float, only proteolytic fungi displayed growth on the media containing 0 and 5% NaCl.