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. Mg 2+ deletion from a medium containing Mg 2+ , Ca 2+ , Co 2+ , and Mn 2+ reduced the yields of all isolates. Ca 2+ deletion from the same medium reduced the growth yields of Bacteroides fragilis, B. fundiliformis , and one strain of B. oralis . The effects of Mg 2+ and Ca 2+ 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.