Understanding the role of the shrimp gut microbiome in health and disease.

With rapid increases in the global shrimp aquaculture sector, a focus on animal health during production becomes ever more important. Animal productivity is intimately linked to health, and the gut microbiome is becoming increasingly recognised as an important driver of cultivation success. The microbes that colonise the gut, commonly referred to as the gut microbiota or the gut microbiome, interact with their host and contribute to a number of key host processes, including digestion and immunity. Gut microbiome manipulation therefore represents an attractive proposition for aquaculture and has been suggested as a possible alternative to the use of broad-spectrum antibiotics in the management of disease, which is a major limitation of growth in this sector. Microbiota supplementation has also demonstrated positive effects on growth and survival of several different commercial species, including shrimp. Development of appropriate gut supplements, however, requires prior knowledge of the host microbiome. Little is known about the gut microbiota of the aquatic invertebrates, but penaeid shrimp are perhaps more studied than most. Here, we review current knowledge of information reported on the shrimp gut microbiota, highlighting the most frequently observed taxa and emphasizing the dominance of Proteobacteria within this community. We discuss involvement of the microbiome in the regulation of shrimp health and disease and describe how the gut microbiota changes with the introduction of several economically important shrimp pathogens. Finally, we explore evidence of microbiome supplementation and consider its role in the future of penaeid shrimp production.

Aciduric Proteobacteria isolated from pH 2.9 soil.

Acidic (pH 2.9) soil was used as an inoculum to culture heterotrophic bacteria at pH values of 3-4. Four isolates were obtained; on the basis of 16S rDNA sequence, they were shown to be members of the beta- and gamma-Proteobacteria. The three isolates that were most closely related to Burkholderia spp. had simple nutritional requirements and could grow in glucose-mineral salts media; two of these used a broad array of organic substrates. The 16S rDNA sequence of the fourth isolate was most similar (96%) to Frateuria aurantia. The isolates were aciduric rather than acidophilic; their pH ranges for growth were approximately 3.5-8. Unlike many bacteria whose acid tolerance represents the capacity to survive acid exposure, these microorganisms carried out exponential growth at pH<4 and their growth rates at pH 3.9 ranged from 60 to 98% of those found at pH 7. The cell yields on glucose of two strains were identical at pH 4 and pH 7. The acidic soils appeared to contain a very diverse bacterial community as assessed by denaturing gradient gel electrophoresis fingerprinting of PCR amplicons of a portion of the 16S rDNA gene. Electronic supplementary material to this paper can be obtained by using the Springer LINK server located at http://dx.doi.org/10.1007/s00203-002-0427-1.