Synergistic action of Acinetobacter baumannii and Talaromyces sp.: Function of enzymes in crude oil degradation

The purpose of this study was to explore the role of intracellular and extracellular enzymes of Acinetobacter baumannii and Talaromyces sp. in the synergistic degradation of crude oil. The extracellular enzymes of Talaromyces sp. contributed more to the degradation of n-alkanes. The degradation rate of n-hexadecane by extracellular enzymes of Talaromyces sp. was 71.83% after 5 days. The concentration of n-hexadecane decreased from 7700 mg/L to 2169 mg/L. This is related to the high extracellular expression of methane monooxygenase (particulate) and aldehyde dehydrogenase (NAD+) in Talaromyces sp. The extracellular enzymes of Acinetobacter baumannii had a better effect on the degradation of aromatic hydrocarbons. The degradation rate of xylene by extracellular enzymes of Acinetobacter baumannii was 35.65% after 5 days. The concentration of xylene decreased from 8600 mg/L to 5514 mg/L. Catechol 1,2-dioxygenase plays a key role in this process. Meanwhile, the degradation enzyme systems of Acinetobacter baumannii (long-chain alkane monooxygenase, alkane 1-monooxygenase, catechol 1,2-dioxygenase, salicylate hydroxylase, and benzoate 1,2-dioxygenase) and Talaromyces sp. (methane monooxygenase (particulate), benzaldehyde dehydrogenase (NAD+), catechol 2,3-dioxygenase, and gentisate 1,2-dioxygenase) complement each other in the degradation process of n-alkanes and aromatic hydrocarbons, thus improving the degradation ability. These results indicated that bacteria and fungi rely on the difference of degrading enzymes to achieve synergistic degradation.