Biosynthesis and genomic analysis of medium-chain hydrocarbon production by the endophytic fungal isolate Nigrograna mackinnonii E5202H

Abstract

An endophytic fungus was isolated that produces a series of volatile natural products, including terpenes and odd chain polyenes. Phylogenetic analysis of the isolate using five loci suggests that it is closely related to Nigrograna mackinnonii CBS 674.75. The main component of the polyene series was purified and identified as (3E,5E,7E)-nona-1,3,5,7-tetraene (NTE), a novel natural product. Non-oxygenated hydrocarbons of this chain length are uncommon and desirable as gasoline-surrogate biofuels. The biosynthetic pathway for NTE production was explored using metabolic labeling and GCMS. Two-carbon incorporation 13C acetate suggests that it is derived from a polyketide synthase (PKS) followed by decarboxylation. There are several known mechanisms for such decarboxylation, though none have been discovered in fungi. Towards identifying the PKS responsible for the production of NTE, the genome of N. mackinnonii E5202H (ATCC SD-6839) was sequenced and assembled. Of the 32 PKSs present in the genome, 17 are predicted to contain sufficient domains for the production of NTE. These results exemplify the capacity of endophytic fungi to produce novel natural products that may have many uses, such as biologically derived fuels and commodity chemicals.

Genome of Diaporthe sp. provides insights into the potential inter-phylum transfer of a fungal sesquiterpenoid biosynthetic pathway

“…Following de novo genome sequencing of fungal isolate BR109, the final genome assembly length was estimated to be 56 Mbp in size across 145 scaffolds, with an N50 of 1.8 Mbp, which is similar to other reported endophyte genomes (Gianoulis et al, 2012; Shaw et al, 2015a; Shaw et al, 2015b). A total of 16,469 predicted genes were identified (Table S1).…”

Identification of a Fungal 1,8-Cineole Synthase from Hypoxylon sp. with Specificity Determinants in Common with the Plant Synthases

“…The previously identified C 7 H 10 compound methyl-1,4-cyclohexadiene was not produced in our cultures based on comparison with an authentic standard, indicating that we may be observing a different subset of these compounds. The largest of the polyene compound peaks was a C 9 H 12 compound that matched the retention time and fragmentation pattern of a compound identified as (3E,5E,7E)-nona-1,3,5,7-tetraene by NMR in a different fungus (82). This is also consistent with the NIST database match for this compound peak.…”

Biosynthesis of hydrocarbons and volatile organic compounds by fungi: bioengineering potential

“…However, some fungal enzymes may be useful in generating shorter alkenes. Specifically, recent work has discovered a nine-carbon alkene from an endophytic fungus isolate of Nigrograna mackinnonii that is likely to be polyketide-derived which approaches a chain length useful for gasoline applications (Shaw et al 2015b). …”

“…Several sesquiterpene synthases have been correlated with products from the basidiomycete Coprinus cinereus, including germacrene A, α-muurolene, δ-cadinene and α-cuprenene (Agger et al 2009). Though no gene has yet to be associated with the jet fuel precursor pinene the genomes of several fungi that produce α and β pinene have been sequenced (Nierman et al 2005; Cuomo et al 2007; Shaw et al 2015a; Shaw et al 2015b). …”