Howard Curtis Berg, a biophysicist who sought to understand the mechanics of bacterial movement, particularly that of E.colidied on December 30, 2021, at the age of 87.
Berg was born in Iowa City on March 16, 1934, according to a obituary from Harvard University. His father was a biochemist at the University of Iowa, and Berg followed a similar path, earning his undergraduate degree in chemistry from Caltech in 1956. According to his resume, he then completed a Fulbright Fellowship at Carlsberg University in Copenhagen before going to Harvard Medical School for preclinical studies. He remained in this position until 1959, when he switched gears and continued his graduate studies at university, obtaining his master’s degree in physics in 1960 and his doctorate in chemical physics four years later. He remained at Harvard teaching and studying cell membrane structure until 1970, when he took a professorship at the University of Colorado at Boulder (CU Boulder).
See “Digital Chemotaxis”
During this time, Berg began to study E.coliuses environmental chemical cues to guide its movement, known as chemotaxis. For this, he invented a microscope capable of following the bacteria’s unpredictable movements, according to the Harvard obituary. He discovered that E.coli was more mobile when placed in conditions with attractive chemical gradients. However, when the environment was poor due to substrate viscosity or other factors, the microbes moved normally, dispelling the popular wisdom at the time that bacteria would actively avoid unfavorable conditions. In 1973 he discovered these flagella move certain bacteria by means of a corkscrew rotation. Berg then returned to the study of bacterial membrane structures as part of his goal of determining the energetics of flagellar movement.
Berg left CU Boulder in 1978 for a year-long sabbatical at the Institut Pasteur in Paris and the State Serum Institute in Copenhagen.
Returning to the United States, he took a professorship at Caltech in 1979, teaching at his alma mater for seven years. During this stage of his career, he used optical tweezers to further probe the dynamics of bacterial movement mechanisms and how they were affected by different stimuli.
See “The optical trap”
In 1983 Berg published the book Random Biology Walksa basic introduction to biological physics.
The following year, he was made a member of the National Academy of Sciences and received the Max Delbrück Prize for Biological Physics from the American Physical Society “for the elucidation of complex biological phenomena, especially chemotaxis and bacterial locomotion, by simple but penetrating physical theories and brilliant experiments.” In 1985, he was elected to the American Academy of Arts and Sciences.
Berg returned to Harvard in 1986. According to his obituary, Berg viewed retirement as “going out to pasture” and so remained active in research until his death. He has published over 120 papers during this time, eagerly embracing emerging technologies to better see or understand aspects of motility.
In February 2022, Berg had a posthumous study published in PNAS which examines how microbes can interact with their environment when on a glass surface. The cover of this month’s issue of Nature Reviews Microbiology was dedicated to Berg and includes a journal article he co-wrote last fall.
He is survived by his wife Mary, three children and five grandchildren.