What types of bacteria, fungi, and viruses inhabit garden soil? Does gardening without gloves affect your own skin microbiome?
In 2019, BioBE’s Dr. Gwynne Mhuireach received a prestigious Postdoctoral Fellowship from the USDA National Institute of Food and Agriculture to study the microbial communities found in urban garden soil, whether they transfer onto people’s hands during gardening activities, and how long they can persist there.
To explore these questions, Dr. Mhuireach recruited 40 community science volunteers to collect soil samples from their gardens and a series of skin swab samples before and after gardening to see if gardening increased the microbial diversity on their hands.
She found that the number of bacteria shared between skin and garden soil increased immediately after gardening for most study participants. However, the imprint of garden soil largely disappeared within 12 hours, likely due to hand washing (which volunteers reported doing a lot more than usual, due to COVID-19). Despite this lack of persistence, a daily gardening routine with repeated and extended contact with soil likely reinoculates the skin such that soil microbes are often present, holding potential to impact health.
It will remain to be seen whether those microbes could have health benefits or cause problems for gardeners. Recent research suggests that more microbial diversity on skin may help reduce allergies, however, a variety of pathogens are also common in soil.
This study is part of a series of work surrounding our connection with plants, soil, and nature in general. Check out our study on the microbial transfer between people and indoor plants here.