Jillian Fiona Banfield FRS FAA (born Armidale, Australia) is professor at the University of California, Berkeley with appointments in the Earth Science, Ecosystem Science and Materials Science and Engineering departments.^[3] She is the director of microbiology the Innovative Genomics Institute, is affiliated with Lawrence Berkeley National Laboratory and has a position at the University of Melbourne, Australia.^[3] Some of her most noted work includes publications on the structure and functioning of microbial communities and the nature, properties and reactivity (especially crystal growth) of nanomaterials.^[1][4][5]

Banfield was educated at the Australian National University where she completed her bachelor's^[6] and master's degrees^[7] (1978–1985) both examining granite weathering. She attributes her initial interest in geomicrobiology to Dr Tony Eggleton who drew her attention to processes at the earth's surface, mineral weathering and the regolith.^[8]

Banfield graduated with a PhD in Earth and Planetary Sciences from Johns Hopkins University for high-resolution transmission electron microscopy (HRTEM) studies of metamorphic reactions supervised by David R. Veblen.^[2][9]

Banfield is an earth scientist who studies the structure, functioning and diversity of microbial communities in natural environments and the human microbiome.^[3] Banfield was part of a group that discovered a process called environmental transformation sequencing, which is a way to manipulate and identify the changeable microbes in a community.^[10] Using environmental transformation sequencing, the group was able to understand how easy it is to genetically modify different bacteria species, using a numerical method.^[10] Her laboratory and collaborators pioneered the reconstruction of genomes from natural ecosystems and community metaproteomic analyses.^[3] Through genomics, her group has provided insights into previously unknown and little known bacterial and archaeal lineages, leading to a new rendition of the Tree of Life.^[3] She has conducted extensive research on natural and synthetic nanomaterials, exploring the impacts of particle size on their structure, properties and reactivity.^[3] Her lab described the oriented attachment-based mechanism for growth of nanoparticles and its implications for development of defect microstructures.^[3] She has also studied microorganism-mineral interactions, including those that lead to production of nanomaterials.^[3]

Banfield was a Fulbright Student in Medicine from the Australian National University to Johns Hopkins University in 1988,^[11] and a Mac Arthur Fellow in 1999.^[12] She has been a professor at the University of Wisconsin–Madison from 1990 to 2001 and the University of Tokyo (1996–1998).^[9] Since 2001, she has been a researcher and professor at the University of California Berkeley^[13] where she heads the geomicrobiology program and works as a researcher at the Lawrence Berkeley National Laboratory. Her research as of 2021 spans field sites in Northern California to Australia and covers subjects at the intersection of microbiology and geosciences, including genome-resolved metagenomics, genome editing tool development, astrobiology and microbial carbon capture.^[14][15] In 2023, Banfield became the first woman to win the Leeuwenhoek Medal from the Royal Dutch Society for Microbiology, an award that that has been given roughly every 10 years since 1875 to honor scientists who have made outstanding contributions to science, society and outreach in the field of microbiology.^[16]