Penicillium citreosulfuratum Isolated from Corroded Parts of a Hydroelectric Power Plant: Characterization and Control with Essential Oils

Abstract

A Penicillium sp. strain was isolated from corroded parts in the Coaracy Nunes hydroelectric power plant in Amapá State, Brazil. Morphological and molecular techniques identified this strain as Penicillium citreosulfuratum Biourge, whose 5.8S-ITS rDNA sequence grouped well in a phylogenetic tree with other Exilicaulis section species of the Penicillium genus. The obtained strain of P. citreosulfuratum ability to form biofilm on the surface of aluminum wires was confirmed by optical and scanning electron microscopy. In plates containing PDA or T&K media, the P. citreosulfuratum strain growth was inhibited around a paper disk containing a highly concentrated solution of copper, iron, or nickel. However, there was no inhibition halo around the paper disk containing aluminum and there was a faint halo around the paper disk containing zinc. This fungus was able to grow in a modified T&K liquid medium containing 50 mM of Al³⁺ and less efficiently in the same medium but containing 50 mM Zn²⁺. The essential oils of melaleuca, mint, thyme, and oregano at 100% inhibited the fungus growth. Oregano essential oil inhibited the P. citreosulfuratum strain growth in concentrations as low as 10%. In conclusion, the results show that the obtained strain of P. citreosulfurarum can form a biofilm on aluminum wires, it grows in the presence of a high concentrations of aluminum and zinc, and essential oils can control its growth.

Keywords:
Penicillium citreosulfuratum ; Biofilm; Metal ions; Essential oils

HIGHLIGHTS

• A strain of Penicillium citreosulfuratum was isolated from corroded metal.

• The fungus formed biofilm on the surface of aluminum wire.

• This strain grew in the presence of 50 mM Al³⁺ in liquid medium.

• Thyme, oregano, and melaleuca essential oils inhibited this strain growth.