Isoprene is the world's most abundant biogenic volatile hydrocarbon, and its annual contribution to greenhouse gas emissions is similar to the carbon dioxide equivalent of methane. However, the degradation and transformation of isoprene in the environment is still unclear.

The Environmental Microbial Ecology Research Team of the Institute of Applied Ecology of the Chinese Academy of Sciences (CAS) has been engaged in the research of biogeochemistry mediated by anaerobic microorganisms. Recently, the research team started to examine the synergistic interaction of carbon reduction and pollution control with the purpose to meet the national strategic needs of carbon peaking and carbon neutrality. In a new paper published by the research team, Researcher YANG Yi and doctoral student JIN Huijuan of the research team used the sediment collected from Xihe River in Shenyang City as inoculum source and established a microcosmic culture system for the anaerobic conversion of isoprene.

The researchers found that microorganisms in the anaerobic enrichment culture system could completely convert isoprene to 2-methyl-1-butene (97%) and 3-methyl-1-butene (3%), and that a new Acetobacterium strain, named Acetobacterium wieringae strain Y, was the functional strain responsible for the anaerobic transformation of isoprene, and that the strain Y utilized the Wood-Ljungdahl Pathway (WLP) to reduce CO₂ and generate acetic acid, while converting isoprene through a metabolic hydrogenation mechanism. 

In addition, the researchers identified the ene-reductases that could be involved in the conversion of isoprene through comparative proteomic and genomic analyses. These enzymes, as biocatalysts, has strong industrial application prospects in the production of high-efficiency biofuels, pharmaceuticals and agricultural chemicals. 

This study reveals that the acetogenic bacteria Acetobacterium wieringae are closely associated with the conversion processes of isoprene and CO₂ in an anaerobic environment, which helps the understanding of the environmental fate of isoprene-related carbon sources and the assessment of global carbon cycle flux models.

This study, funded by the National Natural Science Foundation of China, the National Key R&D Program and the Key Research Program of CAS for Frontier Sciences, has been published in mBio entitled "Anaerobic biohydrogenation of isoprene by Acetobacterium wieringae strain Y."