The Redox Potential of Growing Cultures of Streptococcus Rovis Orla-Jensen Compared with Other Facultative Anaerobes

Abstract

The changes of redox potential were measured in growing cultures of three strains of Streptococcus bovis, together with three strains of Staphylococcus aureus and one strain of each of Lactobacillus plantaram, Lactobacillus casei, and Eschericia coli. It was found that both S. aureus and E. coli could reduce the redox potential of the growth medium to very low values (between —400 mv and —600 mv), whereas the streptococci and lactobacilli were able to cause only slight or insignificant changes of the redox potential. Respirometric measurements confirmed that the capacity of oxygen consumption of S. bovis was very small compared to that of E. coli and S. aureus. On this basis the authors conclude that S. bovis in all probability is unable to contribute significantly to maintenance of the low redox potential of its natural habitat, the rumen. This function must be carried out by other bacteria, such as enterobacteria or staphylococci, which are capable of performing a true, aerobic respiration.

Sammendrag

Ændringen af redox potentialet under væksten blev målt i kulturer af tre isolater af Streptococcus bovis, tre isolater af Staphylococcus aureus og et isolat af henholdsvis Lactobacillus casei, Lactobacillus plantarum og Escherichia coli. Målingerne viste, at S. aureus og E. coli kunne sænke redox potentialet i vækstmediet til meget lave værdier (mellem —400 mV og —600 mV), medens isolaterne af Streptococcus og Lactobacillus kun reducerede redox potentialet ganske ubetydeligt. Respirometriske målinger bekræftede, at S. bovis kun kunne forbruge ganske lidt ilt sammenlignet med E. coli og S. aureus. Det konkluderes ud fra disse målinger, at S. bovis ikke er i stand til at medvirke væsentligt til opretholdelsen af et lavt redox potentiale i vommen. Denne funktion varetages formentlig af andre bakterier, f. eks. enterobakterier og staphylokokker, som er i stand til at iværk-sætte en egentlig aerob respiration.