Screening and molecular identification of lipolytic bacteria associated with a palm oil mill effluent from a palm oil processing plant in Agbogbo, Ile-Ife, southwestern Nigeria

Abstract

We characterized palm oil mill effluent (POME)-isolated bacteria capable of producing lipase. Water samples were collected and serially diluted, and bacteria were isolated from the diluted samples using standard methods. The bacteria were investigated for lipase production using tributyrin agar assay and subsequent fermentation and lipase enzyme analyses. Fifteen bacterial isolates were obtained from POME collected at Agbogbo village, Ile-Ife, Nigeria. Ten of the fifteen bacteria had lipolytic activity, with Bacillus subtilis PO13 having the highest zone of hydrolysis (39.67 ± 2.08 mm), followed by Bacillus subtilis PO1 (27.3 ± 1.53 mm) and Acinetobacter johnsonii PO3 (26.66 ± 1.53 mm). Staphylococcus saprophyticus had the smallest zone of hydrolysis of 11.00 ± 1.0 mm. Further analysis for lipolytic activity using submerged fermentation medium showed that Morganella morganii PO6 had the highest lipolytic activity of 20.67 ± 0.90 U/mL, followed by Bacillus subtilis PO13 with 19.13 ± 0.35 U/mL and Bacillus subtilis PO1 with 18.43 ± 0.57 U/mL, while Bacillus cereus PO15 had the least lipolytic activity of 3.20 ± 2.61 U/mL. The 10 lipaseproducing bacteria characterized by colonial and biochemical characteristics were confirmed by 16S rRNA gene sequencing are Bacillus subtilis PO1 (PZ740870), Bacillus altitudinis PO2 (PZ740854), Staphylococcus equorum PO4 (PZ741005), Staphylococcus saprophyticus PO10 (PZ741035), Acinetobacter johnsonii PO3 (PZ740785), Bacillus subtilis PO13 (PZ740880), Bacillus cereus PO15 (PZ740867), Klebsiella pneumoniae PO9 (PZ740886), Escherichia coli PO7 (PZ740885), and Morganella morganii PO6 (PZ740970). The study concluded that the POME-receiving Agbogbo stream harbours lipase-producing bacteria that could be harnessed for oil-rich wastewater treatment.