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Production of α-1,3-L-arabinofuranosidase active on substituted xylan does not improve compost degradation by Agaricus bisporus

Summary

This research investigated whether genetically modifying commercial mushrooms to produce an enzyme that breaks down plant fiber could improve mushroom production. While the modified mushrooms successfully produced the new enzyme, it didn’t help them break down compost better or produce more mushrooms. This suggests that other factors limit mushroom growth besides their ability to digest plant material. Impacts on everyday life: – Helps understand what limits mushroom production efficiency – Provides insights for developing better mushroom growing methods – Demonstrates challenges in improving agricultural waste recycling – Shows how genetic modification can introduce new enzyme activities in fungi

Background

Agaricus bisporus mushrooms are commercially produced using wheat straw based compost. About 40% of the compost polysaccharides remain unused during mushroom growth and development. Double substituted arabinoxylan is a major component that accumulates because A. bisporus lacks α-1,3-L-arabinofuranosidase (AXHd3) enzymes needed to break down xylosyl residues with double arabinosyl substitutions.

Objective

To assess whether introducing AXHd3 enzyme activity in A. bisporus could improve its ability to degrade compost substrate and potentially increase mushroom yield by expressing the AXHd3-encoding hgh43 gene from Humicola insolens.

Results

The transformants successfully produced active AXHd3 enzyme as demonstrated by their ability to degrade double substituted arabinoxylan oligomers in compost extract. However, no differences were found in carbohydrate composition or arabinoxylan substitution patterns in compost colonized by transformants compared to wild-type A. bisporus. Mushroom yields of transformants were 80-100% of wild-type levels.

Conclusion

Although the genetic modification successfully introduced AXHd3 activity, it did not improve compost degradation or mushroom yield. The double substituted arabinoxylan may be inaccessible due to hemicellulose-lignin crosslinks. The results suggest mushroom formation is limited by factors other than sugar acquisition, such as mycelium differentiation state.
  • Published in:PLOS One,
  • Study Type:Experimental Research,
  • Source: 10.1371/journal.pone.0201090
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