Laccase enzymes produced by both soil bacteria and fungi play important roles in refractory organic matter turnover in terrestrial ecosystems. But, do you know which group (bacteria or fungi) has more close relationship to laccase activity, especially in arable lands? In fact, fungal laccase genes have been extensively studied in various ecosystems, but there were only several studies describing the bacterial laccase-like genes in environmental samples.

Some studies suggested that fungi might play a less important role than expected. Increasing evidences also showed that a wide occurrence of bacterial laccase-like genes could significantly contribute to (Soil organic matter) SOM turnover. Recent research demonstrated the enzyme activity was significantly correlated with the corresponding genes-encoding microbial community. Thus, laccase activity may be highly related to bacterial laccase-like genes but not fungal laccase genes in subtropical arable land.

A team of researchers from the Institute of Subtropical Agriculture, Chinese Academy of Sciences (ISA) sampled from typical six sites containing the main soil types and agricultural land uses in subtropical China, and then detected the laccase activity and the abundance, diversity and composition of bacterial laccase-like genes and fungal laccase genes.

The researchers found that the bacterial laccase-like genes had greater abundance, richness and Shannon-Wiener diversity than fungal laccase genes of basidiomycetes. But, the fungal laccase genes of ascomycetes had not been detected in subtropical arable lands. "An investigation into both fungal laccase genes and bacterial laccase-like genes in one ecosystem is currently limited,"said Prof. SU Yirong, lead researcher  from ISA. "Although our study investigate all of the microbial groups containing bacterial laccase-like genes and fungal laccase genes based on the present published primers, it is still a challenging to classify bacterial laccase-like genes due to the currently poor annotation in the NCBI databases."

The researchers also attempted to establish whether there was a relationship between bacterial laccase-like genes/ fungal laccase genes and laccase activity. Finally, the results showed that laccase activity can be explained almost exclusively by the bacterial laccase-like genes, and their abundance had significant linear relationship with laccase activity. The study has shown that bacteria containing laccase-like genes are the main microbial group for laccase activity, and bacteria may play a more prominent role than fungi in the turnover of recalcitrant organic matter in subtropical arable soils. But, whether this is a ubiquitous phenomenon in other ecosystems remains to be proven."

This Project was supported by the National Science-technology Support Plan Projects (Grant No. 2012BAD05B06), the National Natural Science Foundation of China (Grant Nos. 41301273, 41430860 and 31270551) and the Western Light Project.

The study entitled "Laccase activity is proportional to the abundance of bacteriallaccase-like genes in soil from subtropical arable land" has been published in Volume 31, Issue 12, December 2015 of World J Microbiol Biotechnol, details could be found at http://link.springer.com/article/10.1007/s11274-015-1944-9.