# Complete Genome Report of a Hydrocarbon-Degrading _Sphingobium yanoikuyae_ S72
## 4 Discussion
We also noted several copies of other essential genes for the degradation of hydrocarbon. For example, there were 18 genes that are associated with the cytochrome P450 superfamily. The cytochrome P450 is a monooxygenase, which is involved in the degradation of hydrocarbon. A recent report showed that cytochrome P450 can play important role in the degradation of naphthalene and pyrene [41]. The presence of cytochrome P450 monooxygenase (CP450) in S72 may be due to its role in helping S72 in the degradation of hydrocarbons. CP450's importance in S72 is evident with the presence of many of its copies in S72. Eighteen genes which are member of CP450 superfamily were found in S72. The role of the unique CP450 gene could not be fully explained here but it is likely that they are involved in some pathways that are associated with the degradation of hydrocarbon. Similarly, several genes which have been linked with the degradation of tetrachloroethane were seen in the genome of S72. These genes include nitrilotriacetate monooxygenase (A6768_04895, EC 1.14.13. ), aldehyde dehydrogenase (A6768_04870, EC 1.2.1.3), and alcohol dehydrogenase (A6768_22375, EC 1.1.1.1). There are 22 genes in these three categories that have been associated with the degradation of tetrachloroethane. Tetrachloroethane (CCl4) and trichloroethanes are organic solvents commonly used for laundries and metal cleaning; as a result, they are often found as environmental pollutants [42]. No aerobic bacteria have been reported to possess the ability to degrade CCI4 [43]. The presence of genes needed to degrade CCI4 may suggest that S72 may be effective for the decontamination of an area polluted by CCI4. S72's ability to grow in and degrade naphthalene is associated with the presence of some genes in its genome. The genome has six genes which are involved in the pathway for the degradation of naphthalene (alcohol dehydrogenase, aldehyde dehydrogenase, and nitrilotriacetate monooxygenase). Although these genes are not the only ones that are needed in the pathway for the degradation of naphthalene, their presence in S72's genome may be the reason for its naphthalene degradation. More so, there are several hypothetical genes in S72 which are in the same operon with some genes that take part in the degradation of hydrocarbons (Figure S3) and, as such, may be complementing the roles of the identified genes in the degradation of naphthalene (Figure S3). Most genes in this region had been previously reported to play an essential role in the adaptation to hydrocarbon environment, uptake of hydrocarbon, utilization, and degradation of hydrocarbon. They include the lysR family protein gene which is known to play significant role in the regulation of bacterial adaptation to stress and the use of hydrocarbon. [PERSON] et al. (2017) reported that lysR are part of the two-component system in bacteria through which they sense and respond to the presence of PAH in their environment [8]. Comparative genomic analysis of S72 showed that it is more closely related to the _S. yanoikuyae_ strain UBA2097 because it shares 97% average nucleotide identity with it. Further analysis on its genome showed that it has higher abundance in some cog categories (mo-bilome: prophages, transposons (COG X), secondary metabolites biosynthesis, transport and catabolism (COG Q), carbohydrate transport and metabolism (COG G), lipid transport and metabolism (COG I), cell wall/membrane/envelope biogenesis (COG M), replication, recombination, and repair (COG L), inorganic ion transport and metabolism (COG P), transcription (COG K), posttranslational modification, protein turnover, chaperones (COG O), and general function prediction only (COG R) when compared with previously described hydrocarbon degrading bacteria retrieved from the JGI_IMG database. Many enzymes that are essential for the degradation of hydrocarbon by bacteria have been reported to be encoded by genes in some of the COG categories that were found in abundance in S72 [40].