Luck Mushrooms LLC Toxic Soil Remediation

Here is our latest Bioremediation project, attempting to heal soil that has been contaminated with engine oil spills.

Early in this experiment, Pearl oyster mushrooms emerging from the soil appears to have held the oil in the mushroom cap, removing it from the soil, but not yet degraded, as this was 2 weeks into the project.

Here is the latest Research Report done by Luck Mushrooms LLC (Zach Schondelmayer) and sent to Grand Valley State University:

Mycoremediation of Hydrocarbon-Contaminated Soil Using Pleurotus ostreatus Mycelium

Zach SchondelmayerGrand Valley State University, Natural Resource Management Program

Abstract:This study investigates the potential of Pleurotus ostreatus (pearl oyster strain) for remediating hydrocarbon-contaminated soil. Two 5-gallon buckets of soil, sourced from a community garden, were contaminated with 0.9 quarts of engine oil to achieve 5% contamination by volume. One bucket was inoculated with P. ostreatus sawdust spawn, prepared in advance, along with soaked pasteurized aspen wood chips, while the other remained untreated as the control. Mushrooms (pearl oyster strain) appeared in the inoculated soil before radishes were planted, showing their natural cream colored caps, surrounded by an uncharacteristic blackish-blue margin. Radishes in the fungal-treated soil survived longer than those in the control. Carrots were planted after the radishes and will be observed for an additional 3-5 weeks. This and other research demonstrates that P. ostreatus can effectively remediate hydrocarbon-contaminated soils at a very low cost, suggesting its potential for large-scale applications such as roadside contamination cleanup.

Introduction:The contamination of soil with petroleum hydrocarbons is a significant environmental issue, with detrimental effects on soil health, plant growth, and overall ecosystem function. Bioremediation, using microorganisms and fungi, is a promising strategy for addressing hydrocarbon pollution due to its ability to degrade contaminants and restore soil health (Chiu et al., 2008; Adebayo-Tayo et al., 2020). Pleurotus ostreatus, a white-rot fungus, has been shown to break down complex hydrocarbons, such as those found in engine oil, by producing extracellular enzymes that degrade the carbon structures (Adebayo-Tayo et al., 2020). This study aims to evaluate the efficacy of P. ostreatus (pearl oyster strain) in remediating soil contaminated with used engine oil, while also monitoring its effects on plant growth using radishes and carrots as bioindicators.

Materials and Methods:

• Soil and Contamination: Soil was retrieved from a community garden and contaminated with 0.9 quarts of used engine oil in each of two 5-gallon buckets. The amount of oil used was calculated to achieve a 5% contamination level, based on the volume of the soil in each bucket. This level of contamination is consistent with the typical concentration found in polluted sites (Chiu et al., 2008).

• Sawdust Spawn and Wood Chip Preparation: P. ostreatus sawdust spawn (pearl oyster strain) was prepared by sterilizing sawdust and inoculating it with liquid culture mycelium. In addition, soaked pasteurized aspen wood chips were added to the soil before inoculation. The inoculated soil was left to colonize for several weeks to ensure the mycelium could establish itself.

• Inoculation: One bucket was inoculated with the prepared sawdust spawn and soaked wood chips, while the other bucket remained untreated and served as the control.

• Fungal Activity Monitoring: Prior to planting radishes, mushrooms from the inoculated soil appeared, showing the characteristic creamy off-white tan caps of the pearl oyster strain, with an uncharactoristic blackish-blue ring of color around the margin. This indicated active fungal colonization and potential biodegradation of hydrocarbons (Adebayo-Tayo et al., 2020).

• Planting: Radish seeds were planted after one month of fungal colonization. After three weeks, radishes were removed and carrot seeds were planted for further observation over 3-5 weeks.

Results:

• Mushroom Growth: In the inoculated bucket, P. ostreatus mushrooms began fruiting before radish seeds were planted. The mushrooms exhibited creamy off-white tan caps, typical of the pearl oyster strain, and showed visible signs of oil-related discoloration on the caps. This suggests that the mycelium was actively interacting with the oil in the soil (Adebayo-Tayo et al., 2020).

Figure 1 Shows the Pleurotus ostreatus fruiting body growing in the oil-contaminated soil, with an unusual darkened ring around the cap margin. This particular species strain is Pearl oyster, a cream-colored mushroom.

• Radish Growth: Radishes in the control soil died after three weeks, showing symptoms of toxicity, while those in the inoculated soil survived for an additional two weeks, indicating that the P. ostreatus was mitigating some of the oil's toxic effects.

• Carrot Growth: Carrots were planted after the radishes were removed. Both control and inoculated soils supported similar carrot growth, although further observation is needed to evaluate any long-term differences. This will be monitored for the next 2-4 weeks.

Discussion:The appearance of P. ostreatus mushrooms in the inoculated soil indicates that the fungus was actively colonizing and likely breaking down hydrocarbons in the soil. Previous studies have shown that P. ostreatus can degrade a wide range of organic pollutants, including petroleum hydrocarbons, by secreting ligninolytic enzymes such as laccase and manganese peroxidase, which break down complex carbon compounds in oil (Adebayo-Tayo et al., 2020). The extended survival of radishes in the fungal-treated soil suggests that the fungus reduced the toxic effects of the oil, supporting the potential of P. ostreatus as an effective bioremediator in hydrocarbon-contaminated environments. However, the similar growth of carrots in both control and inoculated soils suggests that further bioremediation may be necessary to fully recover the soil’s fertility. Additionally, it is important to consider that the amount of bioremediation achieved depends on factors such as the concentration of contaminants, the fungal strain used, and environmental conditions (Chiu et al., 2008).

Using straw instead of wood chips could further optimize the remediation process by accelerating the colonization of mycelium. Straw provides a higher surface area for the mycelium to colonize, potentially leading to faster degradation of hydrocarbons (Irshad et al., 2022). This could reduce the time needed for P. ostreatus to degrade the oil and improve soil health in a shorter period.

Notably, the total cost of this project was minimal (when prepared in-house). The sawdust was sourced free from a local mill, and the P. ostreatus liquid culture was prepared from a biopsy of a previously cultivated mushroom. This highlights the low-cost potential of using P. ostreatus for bioremediation in large-scale applications, particularly for roadside contamination, which could be remediated without requiring significant financial investment. This makes it an attractive solution for land management and environmental restoration projects in areas with limited funding.

Conclusion:The study suggests that P. ostreatus has significant potential for remediating hydrocarbon-contaminated soils, as evidenced by the survival of radishes in the fungal-treated soil. The use of P. ostreatus for mycoremediation of engine oil provides valuable insights into its application in environmental restoration. Further observation of carrot growth in the coming weeks will offer more data on the long-term benefits of this approach. Additionally, exploring the use of straw as a substrate could further enhance the bioremediation process by promoting faster mycelial colonization. Given the low cost of the project, this method holds promise for addressing hydrocarbon contamination on roadside soils and other contaminated sites.

References:Adebayo-Tayo, B. C., et al. "A Dualistic Approach to Investigate the Remedial Potential and Edible Property of Pleurotus ostreatus on Hydrocarbon-Contaminated Soil." Sustainability, vol. 12, no. 8, 2020.Chiu, Siu-Wai, et al. "Removal of Spilled Petroleum in Industrial Soils by Spent Compost of Mushroom Pleurotus pulmonarius." Environmental Pollution, vol. 156, no. 3, 2008.Irshad, Muhammad, et al. "Mycoremediation Potential of Pleurotus Species for Heavy Metals: A Review." Journal of Environmental Management, vol. 316, 2022."Mycoremediation as a Potentially Promising Technology: Current Status and Prospects." Sustainability, vol. 15, no. 5, 2023.