Microorganisms of the San Francisco sour dough bread process. II. Isolation and characterization of undescribed bacterial species responsible for the souring activity

Appl Microbiol. 1971 Mar;21(3):459-65. doi: 10.1128/am.21.3.459-465.1971.


A medium was developed which permitted isolation, apparently for the first time, of the bacteria responsible for the acid production in the 100-year-old San Francisco sour dough French bread process. Some of the essential ingredients of this medium included a specific requirement for maltose at a high level, Tween 80, freshly prepared yeast extractives, and an initial pH of not over 6.0. The bacteria were gram-positive, nonmotile, catalase-negative, short to medium slender rods, indifferent to oxygen, and producers of lactic and acetic acids with the latter varying from 3 to 26% of the total. Carbon dioxide was also produced. Their requirement for maltose for rapid and heavy growth and a proclivity for forming involuted, filamentous, and pleomorphic forms raises a question as to whether they should be properly grouped with the heterofermentative lactobacilli.

MeSH terms

  • Acetates / biosynthesis
  • Bacteria / classification
  • Bacteria / cytology
  • Bacteria / drug effects
  • Bacteria / growth & development
  • Bacteria / isolation & purification*
  • Bacteria / metabolism
  • Bread*
  • California
  • Carbon Dioxide / biosynthesis
  • Culture Media
  • Drug Resistance, Microbial
  • Food Handling
  • Food Microbiology*
  • Hydrogen-Ion Concentration
  • Lactates / biosynthesis
  • Lactobacillus / classification
  • Maltose / metabolism
  • Oxygen
  • Peptide Hydrolases
  • Saccharomyces
  • Sodium Chloride / pharmacology
  • Surface-Active Agents
  • Temperature


  • Acetates
  • Culture Media
  • Lactates
  • Surface-Active Agents
  • Carbon Dioxide
  • Sodium Chloride
  • Maltose
  • Peptide Hydrolases
  • Oxygen