Sodium and Other Inorganic Growth Requirements of Bacteroides amylophilus1

AUTOR(ES)
RESUMO

Bacteroides amylophilus has growth requirements for Na+, PO43−, K+, and small quantities of Mg2+. No requirement could be shown for Ca2+ in media previously found growth-yield-limiting for Bacteroides succinogenes. Deletion of Co2+, Mn2+, Cl−, or SO42− did not affect growth. Quantitative studies indicate that Na+, K+, and PO43− have differing effects on the growth of B. amylophilus. A concentration of sodium and potassium ions affects both growth rate and growth yield, whereas a phosphate concentration markedly affects growth yield, but affects growth rate only slightly, if at all. The sodium requirement of B. amylophilus is absolute. It cannot be replaced by K+, Li+, Rb+, or Cs+. The latter three monovalent cations are toxic to B. amylophilus if supplied to the organism at Na+-replacing concentrations. K+ is inactive at similar concentrations. The K+ requirement of B. amylophilus may be satisfied by Rb+. The concentration of Na+ required by B. amylophilus for abundant growth suggests that B. amylophilus should be considered a slightly halophilic organism. The results suggest that Na+ may be a more frequent requirement among terrestial bacteria obtained from relatively low-salt environments than has been previously believed.

ACESSO AO ARTIGO

Documentos Relacionados