Isolation of Lactobacillus from Pickled Olives and studying its role in Biodegradation of Olive Mill Wastewater

Abstract

The olive oil industry produces large quantities of liquid waste called Olive Mill Wastewater (OMW), which is considered one of the most dangerous liquids in different water and land environments due to its high concentrations of toxic organic and phenolic compounds. To reduce its risk, research was conducted to treat thes compounds in different ways, and Biological Treatment proved its effectiveness in degrading these compounds. Bactria, especially Lactobacillus, ferment and sweeten the pickled olives by converting various compounds, including phenols in olive fruits, into acetic acid and other organic compounds. In this research, green pickled olives were prepared and the total bacterial growth counting was studied during four months from pickled olives, as well as the Lactobacillus was isolated from it and incubated in a special growth medium with different concentrations (1, 5, 10, 20 and 25%) of OMW to study the removal ability of these bacteria on the total phenolic compounds present in OMW. The results showed that pickled olive water and OMW contain high concentrations of phenols with an average of 4.83±0.42 and 0.29±4.71 mg/ml, respectively. By comparing the concentration of total phenols at the beginning of the experiment and one month after incubation of Lactobacillus with OMW, it was founded that the mean concentration was greater 0.668±0.18 mg/ml at the beginning of the experiment, while it decreased significantly after one month 0.426±0.07 mg/ml, which indicates that Phenols have been partially removed by isolated Lactobacillus. The highest activity of Lactobacillus biodegradation was recorded at a concentration of 1% of OMW and it was 69% of the total, while the lowest efficacy was at the concentration of 25% of OMW and it did not exceed 25% of the total phenols. A statistically significant inverse linear correlation was found (p<0.05 = 0.036) between both bacterial growth and the total phenolic compounds, which means that whenever the higher the of bacteria in the experimental tubes, the lower concentrations of total phenolic compounds in them, which confirms the ability of Lactobacillus bacteria isolated from pickled olive water to removing harmful phenols in OMW.