Isoprene: The invisible VOC connecting plants, microbes, and climate

My connection to nature began early, shaped by family trips through Colombia’s diverse landscapes — from forest trails and quiet streams to Tayrona beaches and mountain villages like Cerrito. My mother, who grew up in the mountains of Santander, passed on a deep appreciation for the beauty and resilience of plants. Nature became my safe place — a source of peace, curiosity, and eventually, scientific inspiration.

These early experiences led me to study biology and microbiology, seeking to understand the interactions between plants, microbes, and climate. That path eventually brought me to a small but significant molecule: isoprene.

As a biologist, I still turn to nature to feel grounded and inspired. But I’ve also come to ask: what happens when nature itself is stressed?

When temperatures rise and ecosystems shift, plants begin to respond — not always loudly, but sometimes in subtle chemical ways. One of those signals is isoprene (C₅H₈), a volatile organic compound (VOC) that many plants, especially trees, release to cope with heat and oxidative stress. Isoprene has been shown to stabilize plant cell membranes and reduce damage from reactive oxygen species, enhancing thermotolerance (Loreto et al., 2017).

Although naturally produced, isoprene has a major influence on the atmosphere. It reacts with sunlight and other compounds to form ground-level ozone and secondary organic aerosols, which affect air quality and cloud formation. Globally, plants emit over 550 million tonnes of isoprene per year — more than all anthropogenic VOCs combined (Guenther et al., 2012). With rising global temperatures, emissions are expected to increase, especially in northern ecosystems already undergoing rapid change.

During my PhD, I focused on what happens to isoprene after it’s released — specifically, how microbes help degrade it. While most attention goes to emissions and atmospheric chemistry, there’s a lesser-known but crucial story happening closer to the ground. Certain soil and phyllosphere (leaf surface) bacteria can use isoprene as a carbon and energy source, acting as a natural sink that helps remove it from the atmosphere.

To identify these bacteria, we used a method called DNA Stable Isotope Probing (DNA-SIP), which allowed us to track microbes actively incorporating 13C-labeled isoprene in complex environmental samples. This research, including our studies in Environmental Microbiology, highlighted not only soil degraders (El Khawand et al., 2016), but also bacteria living on poplar leaves (Crombie et al., 2018), willow soil/leaves (Larke-Mejía et al., 2019) and oil palm soil/foliage (Larke-Mejía et al., 2022) as active isoprene degraders. These findings expanded our understanding of where microbial isoprene degradation can occur — not only in soils but also directly on plant surfaces.

Now, in my first independent postdoctoral research, I’m exploring how these microbial processes might shift as isoprene emissions increase. I’m using mosses as a model — they’re widespread in Arctic and boreal regions, with varying isoprene emission rates, and their surfaces host rich microbial communities. These moss–microbe systems may be key to understanding how natural isoprene degradation responds to climate change.

Meanwhile, in the atmosphere, isoprene continues its journey. It reacts with oxidants like OH, O₃, and NO₃, forming compounds that influence the climate. A recent Nature study showed that under cold, upper-tropospheric conditions, isoprene oxidation products can contribute to new particle formation, helping seed clouds (Dada et al., 2024). This connects a compound produced by a single leaf to atmospheric processes that influence cloud dynamics and the Earth’s radiation balance.

Six months into my MSCA fellowship, I’m excited about the experiments and discoveries ahead. There’s still so much to learn about how microbes interact with isoprene — and how these tiny organisms may help us understand, and perhaps even soften, the effects of a changing climate.