Nutritional Features of Bacteroides fragilis subsp. fragilis

Abstract

Studies of three reference strains of Bacteroides fragilis subsp. fragilis showed that they grow well in a minimal defined medium containing glucose, hemin, vitamin B 12 , minerals, bicarbonate-carbon dioxide buffer, NH 4 Cl, and sulfide. The vitamin B 12 requirement of 0.1 ng/ml was replaced with 7.5 μg of methionine. Cysteine or sulfide was an excellent source of sulfur, thioglycolate was a poor source, and thiosulfate, methionine, β-mercaptoethanol, dithiothreitol, sulfate, or sulfite did not serve as sole sources of sulfur. Neither single amino acids, nitrate, urea, nor a complex mixture of L-amino acids or peptides effectively replaced ammonia as the nitrogen source. Comparative studies with a few strains of other subspecies of B. fragilis including B. fragilis subsp. vulgatus, B. fragilis subsp. thetaiotaomicron , and B. fragilis subsp. distasonis indicate that they exhibit similar growth responses in the minimal medium. A single strain of B. fragilis subsp. ovatus required other materials. The results indicate the great biosynthetic ability of these organisms and suggest that, in their ecological niche within the large intestine, many nutrients such as amino acids are in very low supply, whereas materials such as ammonia, heme, and vitamin B 12 , or related compounds, must be available during much of the time.

Genetic tools for the redirection of the central carbon flow towards the production of lactate in the human gut bacterium Phocaeicola (Bacteroides) vulgatus

“…P. vulgatus DSM 1447 was obtained from the German Collection of Microorganisms and Cell Cultures (DSMZ; Brunswick, Germany). Cultures were grown anaerobically either in complex brain heart infusion (BHI) medium or in modified Defined Minimal Medium with Glucose (DMMG) in serum flasks sealed with butyl rubber stoppers under an N 2 /CO 2 atmosphere (80%/20%) (Varel and Bryant 1974 ). Prior to inoculation, glucose (30 mM), L-cysteine (0.5 g l −1 ) as reducing agent, vitamin K1 (0.1% (v/v)), and hemin (5 mg l −1 ) were added.…”

Metabolic Synergy between Human Symbionts Bacteroides and Methanobrevibacter

“… M. smithii was initially grown in DSMZ Methanobacterium medium 119 ( 66 ) and then passaged into the modified rich medium supplemented with 10 mM formate and 10 mM acetate with 138 kPa 20% CO 2 80% H 2 headspace atmosphere. The defined medium was designed through a comparison of recipes ( 44 , 45 , 67 – 70 ). Rich medium contained tryptone peptone (10 g), Bacto yeast extract (5 g), 100 mM KPO 4 (pH 7.2), 40 mL TYG salts (0.5 g MgSO 4 ·7H 2 O, 10 g NAHCO 3 , 2 g NaCl per L), 54.4 μM CaCl 2 , 1.4 μM FeSO 4 , 4 μM resazurin, 2.8 mM cysteine·HCl, and 25 μM Na 2 S per L. Defined medium contained 7.5 mM NH 4 SO 4 , 11.9 mM Na 2 CO 3 , 100 mM KPO 4 (pH 7.2), 14 μM FeSO 4 , 50 mL mineral salts (18 g NaCl, 0.53 g CaCl 2 ·2H 2 O, 0.40 g MgCl 2 ·6H 2 O, 0.20 g MnCl 2 ·4H 2 O, 0.20 g CoCl 2 ·6H 2 O per L), 4 μM resazurin, 2.8 mM cysteine·HCl, and 25 μM Na 2 S per L. When indicated, cultures were supplemented with 10 mM sodium acetate, 10 mM formate, 20 μM histidine and 2 μM hematin, 3.7 nM vitamin B 12 (cyanocobalamin), or 5.8 mM vitamin K 3 (menadione).…”

Analysis of Six tonB Gene Homologs in Bacteroides fragilis Revealed That tonB3 is Essential for Survival in Experimental Intestinal Colonization and Intra-Abdominal Infection

“…To test the effect of DtonB mutation on the transport of a specific nutrient, the defined medium described above was modified so that only one nutrient that is expected to be transported by a TonB-dependent transporter is available in the culture medium. This was performed because B. fragilis has an essential requirement for both heme and vitamin B 12 (88), which require TBDTs for their assimilation. However, in the absence of heme, B. fragilis can synthesize heme if protoporphyrin IX and a source of inorganic iron are provided (89,90), and vitamin B 12 can be replaced with L-methionine (88).…”

“…This was performed because B. fragilis has an essential requirement for both heme and vitamin B 12 (88), which require TBDTs for their assimilation. However, in the absence of heme, B. fragilis can synthesize heme if protoporphyrin IX and a source of inorganic iron are provided (89,90), and vitamin B 12 can be replaced with L-methionine (88). Therefore, when required, heme was replaced with protoporphyrin IX plus ferrous ammonium sulfate, and vitamin B 12 was replaced with L-methionine to avoid the presence of multiple substrates that require TBDT for assimilation in the media altogether.…”