Bacteroidaceae Cultivation

Bacteroidaceae is a family of bacteria within the phylum Bacteroidetes. The family Bacteroidaceae includes various bacterial genera, including Bacteroides. Other genera within the family include Alistipes and Parabacteroides. Bacteroidaceae bacteria are Gram-negative, non-spore-forming, and typically anaerobic (although some can be facultative anaerobes). They are widely distributed in various environments, including the gastrointestinal tracts of humans and other animals, soil, and aquatic ecosystems. Members of this family play important roles in both the environment and in human and animal health. Bacteroidaceae appear to be involved in almost all bacterial functional genes categories in the active gut microbiota. Many Bacteroidaceae bacteria are known for their ability to ferment complex carbohydrates. This fermentation process yields short-chain fatty acids (SCFAs) and other metabolites that can be beneficial to the host. Members of the Bacteroidaceae can produce p-cresol.

Figure 1. Bacteroides biacutis anaerobically cultured in blood agar medium

Most of Bacteroidaceae species necessitate anaerobic environments for their growth. We recommend the utilization of pre-reduced media that has either been freshly prepared or previously formulated and stored under anaerobic conditions.

To create pre-reduced media , incorporate a reducing agent (1.5% Na₂S*9H₂O, 3% cysteine, or 5% coenzyme M) into your media preparation, and allow it to stand for at least 30 minutes. These reducing agents facilitate the removal of molecular oxygen and are effective in anaerobic chambers.

You can also access Pre-reduced Anaerobically Sterilized (PRAS) media through commercial sources. PRAS media is meticulously prepared under anaerobic conditions. It undergoes boiling to remove molecular oxygen, followed by the addition of a reducing agent, autoclaving, and dispensing.

For the cultivation of Bacteroidaceae species, rehydrate the vial contents in an anaerobic environment using 0.5 mL of the recommended broth medium. Aseptically transfer this aliquot to 5 mL of the same broth. Simultaneously, you can inoculate an agar slant with the same medium and a blood agar plate, using 0.1 mL of the cell suspension for each.

Incubate the broth and slants under anaerobic conditions at 37°C. For colony formation, incubate the blood agar plates anaerobically, while an aerobic incubation can serve as a contamination check.

Following an appropriate incubation period, which may vary depending on the specific strain, you should observe growth evidenced by turbidity in the broth and colonies on the anaerobic agar surfaces. In contrast, an aerobic blood plate should display no growth.