4.5.2. Bifidobacterium characteristics

Bifidobacterium are typically anaerobic or microaerophilic; however, members of the bee gut Bifidobacterium have been found to grow aerobically (Bottacini et al., 2012). Colonies appear within 2 days and are punctiform, convex, smooth, and greyish-white (Biavati et al., 1982) (Fig. 4). The bee gut Bifidobacterium are negative for catalase and sporulation, Gram positive, and produce lactic and acetic acid (Olofsson and Vásquez, 2008). 

Like Lactobacilli, Bifidobacteria are common members of animal gut microbial communities and have been used as probiotics (Kleerebezem and Vaughan, 2009).  Three species of Bifidobacterium specific to honey bees have been described: B. asteroides, B. coryneforme, and B. indicum (Scardovi and Trovatelli, 1969; Biavati et al., 1982; Felis and Dellaglio, 2007). Other species have been found in bumble bees (Killer et al., 2011). The type strains are available from ATCC: B. asteroides 25910T, B. coryneforme 25911T, and B. indicum 25912T. The genome of B. asteroides strain PRL2011 has been sequenced (Bottacini et al., 2012). Bifidobacterium is present in most adult workers and has been estimated to comprise up to 15% of the gut bacteria (Moran et al., 2012).