Using Ozone to Control Mold in Growing Oyster Mushrooms

Greg Howard
19th May, 2024

Image Source: Natural Science News, 2024

Key Findings

Researchers at the Instituto Tecnológico de Chascomús explored using ozone to decontaminate substrates for oyster mushroom cultivation
Bubbling ozone into water was more effective in reducing green mold (Trichoderma) growth than injecting ozone into a closed tank
Despite ozone treatment, some Trichoderma conidia survived and germinated, but oyster mushrooms still grew well and produced normal yields

Pleurotus ostreatus, commonly known as the oyster mushroom, is one of the most widely cultivated edible mushrooms globally. Its production typically involves using various lignocellulosic substrates, which are treated to eliminate competing microorganisms. Traditional methods for this purpose include pasteurization by steam or immersion in hot water. A recent study conducted by researchers at the Instituto Tecnológico de Chascomús (CONICET-UNSAM)^[1] explored the potential of using ozone as an alternative decontamination method for substrates used in P. ostreatus cultivation, specifically targeting the control of the green mold Trichoderma. The study aimed to evaluate the effectiveness of ozone in two different decontamination methodologies: bubbling ozone into a tank with water and the substrate, and injecting ozone into a closed tank with the substrate inside. Ten different treatments were carried out, including two treatments with inoculation by a spray of Trichoderma conidia (spores). The impact of ozone on the conidia was also assessed. The results indicated that the method of bubbling ozone into water was more effective in reducing Trichoderma growth compared to injecting ozone into a closed tank. However, even with the more effective method, Trichoderma could still grow on the substrate. This suggests that while ozone can affect the conidia, some conidia managed to survive and germinate 72 hours later. Importantly, P. ostreatus was able to grow and produce fruiting bodies on substrates treated with ozone, and the yields were not adversely affected. These findings are consistent with previous research highlighting the antimicrobial properties of ozone. Ozone is known for its strong reactivity, penetrability, and ability to decompose into non-toxic oxygen, making it a viable disinfectant in various applications, including the food industry^[2]. It has been effective against a wide range of microorganisms, including bacteria, molds, yeasts, parasites, and viruses. However, its efficacy can vary depending on several factors such as the physiological state of the culture, pH, temperature, humidity, and the presence of additives^[2]. The study’s findings are also relevant in the context of previous research on the growth and yield of Pleurotus species. For instance, research on different Pleurotus strains isolated from Argentina showed significant differences in growth rates and yields depending on the species and substrate used^[3]. This highlights the importance of optimizing cultivation conditions, including substrate treatment, to improve mushroom yields. One notable aspect of the current study is the comparison of two ozone treatment methodologies. The finding that bubbling ozone into water was more effective than injecting it into a closed tank suggests that the medium through which ozone is applied plays a crucial role in its effectiveness. This aligns with previous observations that the inactivation rates of microorganisms by ozone are higher in systems free of oxidizable organic substances^[2]. Furthermore, the study contributes to the understanding of ozone’s limitations. While ozone did reduce Trichoderma growth, it was not entirely effective in highly contaminated substrates. This underscores the need for further research to optimize ozone application methods and possibly combine them with other treatments to achieve better decontamination results. In conclusion, the study by the Instituto Tecnológico de Chascomús (CONICET-UNSAM) provides valuable insights into the use of ozone as a decontamination agent for substrates in P. ostreatus cultivation. While ozone shows promise, particularly when bubbled into water, its limitations in controlling Trichoderma in highly contaminated substrates highlight the need for continued research and optimization. These findings build on existing knowledge of ozone’s antimicrobial properties^[2] and the cultivation of Pleurotus species^[3], contributing to the ongoing efforts to improve mushroom production practices.

Biochem Plant Science Mycology

References

Main Study

1) Use of Ozone as a Substrate Treatment for the Control of Trichoderma in the Production of Pleurotus ostreatus.

Published 18th May, 2024

https://doi.org/10.1007/s00284-024-03691-z

Related Studies

2) Application of ozone for enhancing the microbiological safety and quality of foods: a review.

Journal: Journal of food protection, Issue: Vol 62, Issue 9, Sep 1999

3) Search for new naturally occurring strains of Pleurotus to improve yields: Pleurotus albidus as a novel proposed species for mushroom production.

https://doi.org/10.1016/j.riam.2010.12.001