Walter Dobrogosz (September 3, 1933 – August 4, 2023) was an American microbiologist who was professor emeritus of North Carolina State University, best known for his discovery and further research on the probiotic bacterium Lactobacillus reuteri.

[1] He grew up in Erie, Pennsylvania, and received his B.S., Masters, and Ph.D. degrees in bacteriology and biochemistry from Penn State University.

Early in his research career, Dobrogosz studied metabolic regulation in such species as Escherichia coli and Salmonella typhimurium.

The focus of Dobrogosz's research shifted in 1985, when he and student Lars Axelsson identified L. reuteri, a new lactic acid bacterium.

Later that year, while on a Fulbright Fellowship to study in Sweden, Dobrogosz and colleague Sven Lindgren discovered that L. reuteri produces a potent anti-microbial substance, which they termed "reuterin."

Dobrogosz and his fellows obtained patents on both the bacterium and reuterin, and later began to market L. reuteri for its benefits to human and animal health.

Dobrogosz founded Probiologics International (PBI) in 1987, a company devoted to the commercial prospects of L. reuteri.

PBI began to carry out human clinical trials, and found that L. reuteri is effective in preventing diarheal diseases and other gut infections.

L. reuteri is now known to maintain intestinal health, prevent fungal, bacterial, and protozoal infections, and mediate the body's immune response.

After retirement, Dobrogosz remained an active advocate of the "probiotic concept"; the importance of microbes in human health.

He continued to publish review articles on L. reuteri, in addition to attending and lecturing at conferences on probiotic and microbiological research.

At Penn State University, he competed on the varsity track and field team as a hurdler.

"Validation of the Probiotic Concept: Lactobacillus reuteri Confers Broad-spectrum Protection against Disease in Humans and Animals".

"Effects of aerobic and anaerobic shock on catabolite repression in cyclic AMP suppressor mutants of Escherichia coli".