_Applied_  
_sciences_  
Biodegradation of High Concentrations of Aliphatic Hydrocarbons in Soil from a Petroleum Refinery: Implications for Applicability of New Actinobacterial Strains  
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rather negative [1; 2]. Modern bioremediation techniques represent both an environmentally friendly and economically feasible means of eliminating petroleum pollutants from soils and sludges [3; 4; 5]. Petroleum hydrocarbons are fairly biodegradable, however their biodegradation can be slow or even fail when hydrocarbon concentrations are high or when they occur in combination with other pollutants (e.g., heavy metals) [6]. A range of bioremediation techniques has been developed in recent years, including biopiling, biocomposting and rhizeremediation; however, these methods are generally based either on biostimulation (i.e., improvement of conditions for indigenous strains of biodegradation microorganisms), bioaugmentation (i.e., introduction of allochthonous biodegradation microbial strains) or a combination of both [3; 7; 8; 9]. Seeking new resistant and metabolically active biodegradation strains capable of degrading of high concentrations of pollutants is important for successful application of bioremediation techniques. Techniques for improvement of biodegradation strains [10] (adaptation for higher toxicities, genetic engineering etc.) have been developed, however the major source of new strains remains their isolation from contaminated soils [9; 11; 12; 13]. Actinobacteria are one of the microbial groups of special interest for bioremediation purposes due to their large genomes, rich metabolism, secondary metabolites, high resilience to toxic pollutants and ability to biodgrade many organics from small volatile to long chain hydrocarbons [14; 15]. Recently new actinobacterial strains applicable for bioremediation have been described or characterized, e.g., _Gordonia_ sp. capable of biodegradation of phthalic esters [16], _Gordonia polyisoprenivorans_ capable of cleavage of poly(_cis_-1,_4_-isoprene) [17], _Gordonia rubripertincta_ CWB2 capable of biodegradation of styrene [10], or _Gordonia phthalatica_ sp. capable of biodegradation of various phthalic esters [18]. Despite significant progress in the prediction of bioremediation processes, a preliminary laboratory experiment is a standard tool before the bulk treatment is commenced. The aim of this study was to test, in a laboratory pot experiments emulating potential bulk treatments, different variants of bioremediation of soil from oil refinery contaminated by high concentrations of aliphatic petroleum hydrocarbons (C\({}_{10}-\)C\({}_{40}\)\(\sim\)80 g\(\cdot\)kg\({}^{-1}\) dry weight). In the initial long-term experiment (Experiment A), we subjected a mixture of two bacterial isolates routinely used in bioremediation applications (_Ochrobarrum_ sp. and _Bacillus_ sp.) to variants of periodic bioaugmentation and biostimulation.