Citation: Gerginova, M.; Stoyanova, K.; Peneva, N.; Dincheva, I.; Alexieva, Z. An Investigation into the Potential of a Penicillium Commune Strain to Eliminate Aromatic Compounds. Processes 2023, 11, 2402. https:// doi.org/10.3390/pr11082402 Academic Editor: Maria Jose Martin de Vidales Received: 11 July 2023 Revised: 1 August 2023 Accepted: 8 August 2023 Published: 9 August 2023 Copyright: © 2023 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/). processes Article An Investigation into the Potential of a Penicillium Commune Strain to Eliminate Aromatic Compounds Maria Gerginova 1 , Katya Stoyanova 1 , Nadejda Peneva 1 , Ivayla Dincheva 2 and Zlatka Alexieva 1, * 1 Department of General Microbiology, Institute of Microbiology, Bulgarian Academy of Sciences, 1113 Sofia, Bulgaria; mariagg@microbio.bas.bg (M.G.); katya_litova@abv.bg (K.S.); peneva_nad@yahoo.com (N.P.) 2 Plant Genetic Research Group, AgroBioInstitute, Agricultural Academy, 1164 Sofia, Bulgaria; ivadincheva@yahoo.com * Correspondence: zlatkama@yahoo.com; Tel.: +359-888-565-523 Abstract: The quantity of industrially polluted waters is increasing everywhere, of which a significant part is occupied by a number of mono- and poly-aromatic compounds. Toxins enter the soil, sewage, and clean water by mixing with or seeping into them from industrial wastewater. By using 18S RNA and ITS sequences, the Penicillium commune AL5 strain that was isolated from Antarctic soil was identified. This study is dedicated to exploring its capacity to metabolize hazardous aromatic compounds. The strain showed very good potential in the degradation of hydroxylated monophenols and possessed exceptional abilities in terms of resorcinol degradation. The strain’s ability to metab- olize 0.3 g/L of p-cresol at 10 ◦ C is notable. The strain is also capable of metabolizing LMW PAHs (naphthalene, anthracene, and phenanthrene) and eliminating all three tested compounds under 23 ◦ C, respectively, 77.5%, 93.8%, and 75.1%. At 10 ◦ C, the process slowed down, but the degradation of naphthalene continued to be over 50%. The quantity of PAH and a few significant intermediary metabolites were determined using GC–MS analysis. Sequencing of the enzymes phenol hydroxylase and catechol 1,2-dioxygenase revealed a close association with the genes and proteins in some fungal strains that can degrade the aromatic compounds examined thus far. Keywords: biodegradation; fungi; oxiganases; PAHs; GC–MS; DNA sequencing 1. Introduction One of the serious problems of our time is the increase in chemical compounds dangerous to human and animal health in waste water. This happens by starting with industrial wastewater and then passing through the mixing or leaching of these toxins into the soil and clean water intended for domestic use. A number of aromatic compounds, both mono-derivatives of phenol and polyaromatic compounds, such as naphthalene, anthracene, phenanthrene, and their higher molecu- lar derivatives, occupy a significant share of these pollutants. Many efforts have been made to characterize microorganisms of different taxonomic affiliations possessing mech- anisms to degrade phenol, catechol, cresols, chloro- and nitro-phenols, and other toxic monophenols [1–6]. Studies devoted to the removal of PAHs from sludges formed in sewage treatment plants and sewage under the influence of aerobic microorganisms are few. Some studies have shown that aeration accelerates the removal of PAHs [7,8]. An essential problem in modern biotechnology aimed at processes related to environ- mental cleaning is overcoming low temperatures in some polluted areas. The capacity of some microorganisms to develop and function at low temperatures is crucial to overcoming these challenges. Studies on psychrophilic and psychrotrophic microorganisms, which can degrade and utilize a variety of environmental contaminants with a diverse chemical composition, are relatively rare [9–12]. In this context, since no additional energy inputs are required for heating and maintaining relatively high temperatures for ex situ degradation, Processes 2023, 11, 2402. https://doi.org/10.3390/pr11082402 https://www.mdpi.com/journal/processes