ABSTRACT
Coolants are hydrocarbons, used to lubricate parts of machines for smooth performance. While in use, a coolant quickly gets contaminated with foreign materials, making it less effective and unpleasant odors are developed due to microbial action. Hence coolants need to be replaced frequently. The expense of disposing used coolants and replacing it with fresh coolants adds significantly to the manufacturing cost. The present study is focused on isolation, identification and characterization of coolant oil contaminating bacteria as an initial step to solve these contamination problems. Used and unused samples of coolant were collected from oil stations, auto mechanic workshops and steel industry for the isolation of the contaminants. Ten dominant bacterial isolates of the genus Pseudomonas, Staphylococcus, Micrococcus, Salmonella, Cellobiococcus and Pneumonia were identified by morphology, biochemical tests and PIB tool. Isolates were subjected to four different media, various pH and temperatures for characterization of optimal conditions of growth. Pseudomonas pseudomallei, Micrococcus luteus 3, Micrococcus varians and Salmonella ferlac were observed in mineral, synthetic and aerobic media, Staphylococcus hyicus, Cellobiococcus species and Staphylococcus intermedius in synthetic and aerobic fermentation media and Pseudomonas cepacia, Pseudomonas piketti in mineral salt and aerobic fermentation media. The ten isolates showed optimal growth at different temperatures between 20°C and 90°C and different pH, ranging from acidic to alkaline. In conclusion, the used coolants harbor hazardous pathogens such as Pseudomonas species which multiply rapidly and survive high temperatures. These isolates could be targeted for further studies on development of antidotes as a solution to the coolant contamination problems.