Microbial community of Pacific abalone (Haliotis discus hannai) juveniles during a disease outbreak in South China

Abstract

A mass mortality of farmed juvenile abalones (Haliotis discus hannai) occurred in South China in December of 2012. Combined traditional culturing with terminal restriction fragment length polymorphism (T-RFLP) methods, microbial communities associated with juvenile abalones were investigated under different survival conditions, including healthy (HA) and moribund (HM) abalones in the healthy pond with low mortalities, and healthy (DA) and moribund (DM) abalones in the diseased pond with a high mortality rate. The results indicated that both HA and DM exhibited greater microbial diversity and evenness. Moreover, the number of bacterial colony forming units (CFUs) from HA and DM were higher than other samples from the same pond. HA and DA samples harboured absolutely dominant T-RFs with 504 bp (76.2% of total T-RFs) and 436 bp (63.2%) respectively. Nesterenkonia sandarakina, Staphylococcus haemolyticus and Agarivorans albus were the dominate isolates in HA samples, but no Vibrio genus was isolated even on vibrio-specific medium. Reversely, in the DM samples, up to 94% of the total bacterial CFUs were composed of the family Vibrionaceae, represented by Photobacterium swingsii (44%) and Vibrio shilonii (45%). Also, Vibrio was the only cultivated genus from the HM group. Of these Vibrio species, V. atlanticus were detected in HM, DA and DM samples and could generate the T-RF 504 bp. The microbial composition and diversity of juvenile abalones in different surviving states provided insights into the stability and dynamics of microbial communities during disease outbreak which could be helpful to predict and to control disease in the future.

Bacteria-Affecting Cephalopods

“…Similar results were also found for culture of clams (Kwan and Bolch 2015). It was also shown that an effective balance of microbial populations included in the same community ensures the final rearing success (Verschuere et al 1997;Kwan and Bolch 2015;Shi et al 2017). Recently, it has been proved that the intestinal microbiome, highly diverse, of octopus paralarvae reared in captivity and feed with Artemia is rapidly become less diverse and is mainly suggested as a consequence of culture conditions (Roura et al 2017).…”

Seasonal microbial profiling of left kidney and stomach of farmed adult greenlip abalone ( Haliotis laevigata )

“…Previous analyses of healthy and diseased juvenile abalone suggested mass mortality events might be caused by changes in the microbial community and understanding the dynamics would provide another approach in the understanding such disease outbreaks (Shi et al., 2017). Vibrio species were also identified in the moribund abalone taken from healthy ponds in Shi's study.…”

“…The traditional morphological and biochemical methods for bacterial identification have been replaced by sequencing. Colony hybridization (Tanaka et al., 2003), sequencing of the cloned 16S rDNA amplicons (Tanaka et al., 2004), denaturing gradient gel electrophoresis (DGGE) fingerprinting (Huang et al., 2010; Zhao et al., 2012), 16S rRNA gene clone libraries (Iehata et al., 2014), restriction fragment length polymorphism (T‐RFLP) methods (Shi et al., 2017), 16S sRNA gene MiSeq paired‐end sequencing (Gobet et al., 2018) and pyrosequencing of 16S rRNA genes (Zhao et al., 2018) have been used for abalone‐related sequencing. Most of the mentioned studies focus on the gastrointestinal microbiome; only Gobet et al included the “gonado‐digestive” gland probably because of the difficulty of excision of this organ.…”

Hazard Identification Related to the Presence of Vibrio spp., Biogenic Amines, and Indole-Producing Bacteria in a Non-Filter Feeding Marine Gastropod (Tritia mutabilis) Commercialized on the Italian Market

“…Bivalve mollusks and gastropods have both an open circulatory system [5], and therefore bacteria and other contaminants can be expected in all organs and tissues, independently of the different feeding habits. Despite this biological evidence, the microbiology of marine gastropods has been poorly investigated, except few studies concerning disease outbreaks of Abalone, reporting high bacterial contamination of tissues also in healthy animals [42], and the study of Cheng et al [43] reporting high contamination of the gastropod Niotha clathrata muscle by Vibrio spp. (6-8 log 10 CFU g −1 ).…”