Characterization of selected actinomycetes degrading polyaromatic hydrocarbons in liquid culture and spiked soil

Abstract

Five strains of the Rhodococcus and Gordonia genera were evaluated for their potential use in bioremediation of polycyclic aromatic hydrocarbons (PAH) with or without another substrate (co-substrate). Their ability to produce biosurfactants or to degrade phenanthrene when growing on glucose, hexadecane and rapeseed oil was tested in liquid medium at 30°C. All strains showed biosurfactant activity. The highest reduction in surface tension was recorded in whole cultures of Rhodococcus sp. DSM 44126 (23.1%) and R. erythropolis DSM 1069 (21.1%) grown on hexadecane and Gordonia sp. APB (20.4%) and R. erythropolis TA57 (18.2%) grown on rapeseed oil. Cultures of Gordonia sp. APB and G. rubripertincta formed emulsions when grown on rapeseed oil. After 14 days of incubation, Rhodococcus sp. DSM 44126 degraded phenanthrene (initial concentration 100 lg ml )1 ) as sole carbon source (79.4%) and in the presence of hexadecane (80.6%), rapeseed oil (96.8%) and glucose (below the limit of detection). The other strains degraded less than 20%, and then with a co-substrate only. Rhodococcus sp. DSM 44126 was selected and its performance evaluated in soil spiked with a mixture of PAH (200 mg kg )1 ). The effect of the addition of 0, 0.1 and 1% rapeseed oil as co-substrate was also tested. Inoculation enhanced the degradation of phenanthrene (55.7% and 95.2% with 0.1% oil and without oil respectively) and of anthracene (29.2% with 0.1% oil). Approximately 96% of anthracene and 62% of benzo(a)pyrene disappeared from the soil (inoculated and control) after 14 days and anthraquinone was detected as a metabolite. Rhodococcus sp. DSM 44126 was identified as Rhodococcus wratislaviensis by 16S rRNA sequencing and was able to degrade anthracene as sole carbon source in liquid culture.

Degradation of polycyclic aromatic hydrocarbons in soil by a two-step sequential treatment

“…The culture was centrifuged (10 min, 970 · g), the supernatant discarded and the pellet washed twice with sterile tap water. The culture was then diluted to an OD 600 of 0.500 and 1 ml was added to tubes containing pyrene (25 lg ml -1 ) as the sole carbon source in 10 ml of minimal salt medium (modified from Mandelbaum et al 1993) and glass beads, as described in Pizzul et al (2006a). The microorganisms were incubated at 30°C for 10 days and the concentration of the remaining pyrene was measured at the end of the incubation time.…”

Microbiotechnology Based Surfactants and Their Applications

“…Occurrences of surfactant-producing microorganisms seems to correlate to environments in which hydrophobic carbon sources are present, no matter if these are oil contaminated or oil enriched (Powalla et al, 1989;Pizzul et al, 2006;Liu et al, 2009;Ruggeri et al, 2009). Evoked by their hydrophobic cell wall due to incorporation and association of various lipoglycosides, actinobacteria preferably grow in hydrophobic droplets that are dispersed in the aqueous phase when cultured in cultivation devices.…”

“…CpI1 n.d. GL Tunlid et al, 1989 Gordonia amarae SC1 n.d. (extracellular with high molecular weight) Iwahori et al, 2001 Gordonia rubripertincta DSM 46038 n.d. Pizzul et al, 2006 Gordonia sp. ADP n.d. Pizzul et al, 2006 Gordonia sp. BS29 n.d. GL Franzetti et al, 2010 Gordonia sp.…”

A practical culture technique for enhanced production of manganese peroxidase by Anthracophyllum discolor Sp4

“…When Tween 80 was used, no significant differences in the MnP activity were observed in the tubes containing glass beads or Erlenmeyer flaks. Pizzul et al (2006) used the glass-beads tube technique to test the PAHs degradation by actinomycetes. The system allowed for both good microbial growth confined to the liquid medium and glass beads matrix and suitable and rapid PAH quantification with a PAHs recovery yield of up to 95%.…”

“…In addition, the biodegradation tests normally require destructive sampling (complete destruction of sample for the analysis), particularly when the target compound is hydrophobic, or is applied at the concentrations where it is insoluble in the growth medium. A practical and simple culture technique using the tubes containing the glass beads has been used for the study of polycyclic aromatic hydrocarbon (PAHs) degradation by the actinobacteria (Pizzul et al, 2006) and could be of interest in the fungal cultures. The purpose of this study was to study the effect of Mn 2+ , Tween80 and lignocellulosic substrate on MnP production by A. discolor Sp4 and to evaluate a simple and practical culture system for MnP production using the tubes containing the glass beads as replacement of Erlenmeyer flasks.…”