Research Projects

Antibiotics are crucial for wellbeing of humans and livestock. Counterintuitively, in the Anthropocene antibiotics pose emerging threats to the environment and to health. About 10 million kg antibiotics are used in veterinary care annually, and this is projected to increase in the coming years. When these enter soil and water, they pose dual threats. First, antibiotic pollution is a major health hazard because it facilitates the evolution of antimicrobial resistance in pathogens. Second, it is an unmitigated climate threat because it alters biogeochemical cycles through its impacts on soil microbes. Mitigating these threats is central to India’s national policies on livestock, and on antibiotics. Compared to the effects of antibiotic on the global carbon cycle, we know very little about their impacts on the nitrogen cycle. We do not know how antibiotic pollution alters microbial community structure and networks, and functions in soil, and whether that affects greenhouse emissions from soil as nitrous oxide and other gases, and its ultimate influence on land-atmosphere climate-feedbacks. This limits our ability to envision policy interventions that would foster a sustainable livestock economy. Here we propose to combine the biological and climate sciences in ways that are relevant to agroecology, biogeochemistry, ecosystem health, microbial networks, and statistical modeling. We propose to address two questions in a hierarchical manner: 1. Do veterinary antibiotics, chiefly tetracycline, alter the soil nitrogen cycle and influence greenhouse emissions (primarily N2O, alongside other gases such as NH3, NO, and NO2). 2. Based on the patterns seen above, a. whether the impact of antibiotics on the nitrogen cycle is explained by concomitant variation in the abundance of functional genes related to nitrification/denitrification, and b. whether the variation in nitrifying/denitrifying genes is explained by shifts in microbial community composition and by shifts in microbial networks. We aim to identify how antibiotics pollution can ultimately also impact climate. With field and laboratory experiments, we will quantify whether veterinary antibiotics alter soil microbial communities to affect nitrogen cycling. We will take advantage of pastoral land use in Spiti region of Himachal Pradesh, which offers natural experiments where soils in replicate watersheds are influenced by antibiotics (livestock: altered state), and these are juxtaposed with a control watersheds (wildlife: reference state). We will use control/treatment experiments with antibiotic application in these watersheds, and long-term laboratory incubations of their soils to address our questions. Filling these key knowledge-gaps would also be relevant to India’s international commitments to UNFCCC and SDG-2030.