Primary co-culture as a complementary approach to explore the diversity of bacterial associations in marine invertebrates: the example of Nautilus macromphalus (Cephalopoda: Nautiloidea)

Identification of a Vibrio strain producing antimicrobial agents in the excretory organs of Nautilus pompilius (Cephalopoda: Nautiloidea)

“…Among these associated bacteria, Vibrionaceae are the most abundant and show antimicrobial activities against both Gram-positive and Gram-negative reference strains. Compared to what is known in N. macromphalus from New-Caledonia (Pernice et al 2006), the present study shows: (i) presence of similar b-Proteobacteria and spirochetes strains in both species with no close environmental relatives, (ii) consistent absence of Vibrionaceae in N. macromphalus from New-Caledonia, (iii) constant presence of Vibrionaceae in N. pompilius from Philippines, closely related to environmental strains. Therefore, we suggest that this antimicrobial active Vibrio infects N. pompilius from Philippines by environmental transmission.…”

“…When compared to the bacterial diversity in pericardial appendages of N. macromphalus, a species endemic of New-Caledonia (Pernice et al 2006), the same clusters were identified for both species, except for the Vibrionaceae, which were not detected in N. macromphalus. However, as Vibrio were consistently found in N. pompilius, it is conceivable that Vibrio is a common inhabitant of N. pompilius PA.…”

“…In nautiloids, a high density of one bacterial morphotype has been observed by transmission electron microscopy in the brush border of the excretory organs (Pericardial Appendages: PA) epithelium of Nautilus macromphalus and N. pompilius (Schipp et al 1985;Schipp et al 1990). However, a recent identification using comparison of 16S rRNA gene sequences has shown an unexpected microbial diversity in N. macromphalus PA (Pernice et al 2006). …”

Occurrence of a specific dual symbiosis in the excretory organ of geographically distant Nautiloids populations

“…First, the bacterial symbionts are concentrated and attached to the outer epithelium in the baso‐medial region of the pericardial villi which is highly active in the ultrafiltration and the reabsorption processes while the apical part of the villi is devoid of any symbionts (Schipp and Martin, 1987). Second, the ultrastructure of the outer epithelium and its polar organization in the symbiotic region of pericardial villi are characteristic of an energy‐requiring, transport active tissue with a high density of mitochondria and ionic pumps (Martin, 1983; Pernice et al ., 2007c). The precise distribution of the bacterial symbionts in this transport active region of the excretory tissue is likely to reflect metabolic interactions with their host tissue based on a three‐step process: (i) the secretion of the excretory fluid by the host tissue; (ii) the degradation and assimilation of compounds present in the excretory fluid by the bacterial symbionts; and (iii) the reabsorption of compounds derived from bacterial assimilation by the host tissue (Fig.…”

“…Further investigations are clearly needed to understand how the betaproteobacteria and spirochaete symbionts are involved in Nautilus excretion but, given their high density in the host tissue (approx. 150 × 10 6 cells per gram of fresh tissue; Pernice et al ., 2007c), it is likely that these symbiotic populations may have a profound effect not only on the function but also on the development of the excretory organs of present‐day Nautiloids.…”