Draft genome sequence and annotation of Rhizopus arrhizus FBL 578 (Mucoromycota): insights into the mycoremediation of DDT-contaminated soils

Fungi can tolerate and transform anthropogenic contaminants such as persistent organic pollutants (POPs), thanks to their metabolic and enzymatic versatility (1, 2, 3). Indeed, fungal biodegradation of POPs, e.g. DDT, has been recognized as an environmentally-friendly, feasible, integrated, cost-effective remediation biotechnology (1, 2, 3). However, the mechanisms underlying detoxification metabolism of organochlorine compounds are still unclear and further investigations could support applications in pesticide-contaminated soils.Strains of the monophyletic genus Rhizopus (Mucoromycota) are widely known for their importance in industrial, medical and environmental sectors (4, 5). Rhizopus sp. FBL 578 (deposited in the fungal collection of the Fungal Biodiversity Laboratory, Sapienza University of Rome), was isolated from Polish DDT-contaminated soil. The tolerance of this strain to 1 mg/L DDT has been investigated by tolerance indices (Rt:Rc (%); T.I. (%)). Metabolic responses to DDT were also evaluated through growth data (diametric extension and dry weight) and medium pH after fungal growth (6). Our results pointed out the potential of FBL 578 in DDT bioremediation. An analysis of DNA sequences from the RPB2, EF-1α, and RNA helicase genes indicated that Rhizopus sp. FBL 578 is closely related to Rhizopus arrhizus A. Fisch (formerly Rhizopus oryzae) of the R. arrhizuscomplex, which are well-known producers of proteolytic enzymes, but certain strains can act as opportunistic human pathogens (mucormycosis) (7). In this study, FBL 578 was the target for whole-genome sequencing (WGS), assembly and annotation to better assess the safety of biotechnological applications in mycoremediation. Mitochondrial sequences were also identified. The assembly for Rhizopus sp. FBL 578 genome consisted of 6,027 contigs totaling a size of 39.3 Mbp with a 35.08% GC content. A total of 14,399 protein-coding genes were predicted, and then annotated with the GO and the CAZy databases. Bioinformatic analyses were conducted on putative genes involved in the metabolism of DDT. Prediction of biosynthesis gene cluster was also carried out to shed light on the genes potentially involved in the production of compounds and secondary metabolites of biotech value. The WGS project of R. arrhizus FBL 578 has been submitted to GenBank (NCBI). The Next Generation Sequencing (NGS) work for the WGS project was financially supported by INAIL-DIT (Rome, Italy). 1) J. Foght, T. April, K. Biggar, J. Aislabie (2001) Bioremediation J., 5, 225-246 2) A. Mansouri, M. Cregut, C. M.-J. AbbesDurand, A. Landoulsiand, G. Thouand (2017) Appl. Biochem. Biotechnol.,181, 309-339 3) H. Harms, D. Schlosser, L.Y. Wick (2011) Nat. Rev. Microbiol., 9, 177-192 4)L. Londoño-Hernández, C. Ramírez-Toro, H. A. Ruiz, J. A. Ascacio-Valdés, M. A. Aguilar-Gonzalez, R. Rodríguez-Herrera, C. N. Aguilar (2017) Int. J. Food Microbiol., 257, 110-112 5)G. Barnita, R. Rinarani (2011) J. Appl. Sci., 11, 2470-2486 6) F. Russo, A. Ceci, F. Pinzari, A. Siciliano, M. Guida, E. Malusà, M. Tartanus, A. Miszczak, O. Maggi, A. M. Persiani (submitted) Appl. Environ. Microb.7) G. Walther, S. Dolatabadi, G. S. de Hoog (2014) Mycoses, 57, 36-36