Mycelial biomass production from residual cannabis stems

Abstract

The harvest of hectares of Cannabis (Cannabis sativa L.) in the form of flowering hemp generates tons of lignocellulosic biomass annually. This significant waste stream is the result of growing only the flowering parts of the plant, which contain concentrated levels of cannabinoids such as CBD. As a result, the remaining 90% of the plant is largely ignored as waste during medical hemp harvesting, which focuses on the removal of flowering tissue. The remaining stems and leaves are often left to decompose in piles, burned or disposed of in landfills after harvest. The issue of sustainable management of residual stems and the resulting biomass has not been addressed. Our group has been studying fungal biomass production from white rot fungi for some time, especially from wild mushrooms in the Cuyo region. In this study, we evaluated the comparative mycelial biomass production of indigenous Trametes fungi (T. sanguinea RSL01 and T. villosa RSL02) from residual cannabis stems mixed with yeast extract and pine sawdust (additives), studying their growth rates and mycelial density. This type of lignocellulosic residue was evaluated as a substrate for mycelial culture and the results were compared to a control substrate of pure (non-composted) cannabis stems, which established a baseline for evaluating biomass production performance. The experiment was carried out in petri dishes for 12 days at 28°C. The best results were observed for cannabis stem without additives, T. sanguinea RSL01 and T. villosa RSL02 achieved growth rates of 0.67 and 0.82 cm/day and high mycelial densities; 253.7 ± 1.9 and 209.07 ± 15.6 (gray scale), respectively. The mycelial density was the most promising result, as the maximum limit is 255. The differences observed between composite and pure substrate were analyzed by analysis of variance (ANOVA), which confirmed good biomass production without the need for additional nutrient additives. These results suggest a wide range of biotechnological applications, from biomaterials to enzyme production, and allow advancing to the next stage in the biomanufacturing of materials.