Inorganic and metal organic growth requirements of the genus Bacteroides

Abstract

The inorganic and metal organic growth requirements of ruminal and nonruminal Bacteroides species were compared. The heme requirement of many nonruminal Bacteroides species was similar to that of Bacteroides ruminicola subsp. ruminicola and was a general tetrapyrrole requirement. Some nonruminal Bacteroides species utilized succinate or alpha ketoglutarate, as well as tetrapyrrole containing compounds, in place of heme. Fe+ as well as heme was required for maximal yields of some Bacteroides species. The divalent cation requirements of Bacteroides species are complex. Mg2+ deletion from a medium containing Mg2+, Ca2+, Co2+, and Mn2+ reduced the yields of all isolates. Ca2+ deletion from the same medium reduced the growth yields of Bacteroides fragilis, B. fundiliformis, and one strain of B. oralis. The effects of Mg2+ and Ca2+ on the growth of Bacteroides isolates was influenced by other divalent cations. Relatively large quantities of Na+ were obligately required by all of the currently recognized predominant rumen Bacteroides species. Nonruminal Bacteroides species either did not require Na+ or required only small amounts. The Na+ requirement of some nonruminal Bacteroides species could be partially replaced by Li+ or Cs+. The Na+ requirement of rumen Bacteroides species was absolute. The inorganic and metal organic growth requirements of Bacteroides species appear useful as aids in species differentiation.