Feeding of β-1,3/1,6-glucan increases the diversity of the intestinal microflora of carp (Cyprinus carpio)

Abstract

b-glucans are immunomodulants that are used in fish nutrition for health improvement. The effect of MacroGard Ò , a commercially available b-1,3/1,6-glucan, on the bacterial community in the gut of common carp (Cyprinus carpio) was examined focusing on species diversity. Separate segments of the gut were analysed. We identified cultured bacteria isolates by analysing 16S rRNA gene sequences and additionally used reverse transcription polymerase chain reaction-denaturing gradient gel electrophoresis (RT-PCR-DGGE) for examination of bacterial diversity. With both methods, we could detect a significantly higher amount of bacterial operational taxonomic units (OTUs) in all examined parts of the gut after feeding with MacroGard Ò . Independent of the feeding regime, mostly motile aeromonads, pseudomonads and Vibrio sp. could be detected in the intestinal community of carp. Shewanella putrefaciens and Vibrio sp. were regular components of the intestinal microflora but were present to a lesser extent in the microbial community of carp fed with MacroGard Ò . This could have a positive effect for fish health and also in respect of food safety for fish destined for human consumption. Our results suggest that feeding of MacroGard Ò results in a more diverse intestinal community that could help to prevent the invasion and establishment of pathogenic micro-organisms.

Flavobacteria as secondary pathogens in carp suffering from koi sleepy disease

“…Gill swabs were collected from the donor fish used in the: “Confirmation of bacteria transfer and bacteria identification” Experiment 2 (CEV Genogroup I) and Experiment 3 (CEV Genogroup IIa), inoculated in a flavobacteria selective agar (Cytophaga Agar Base, Criterion) and cultivated at 15 and 25°C. Pure colonies were collected and subjected to identification by sequencing a fragment of the 16S rRNA encoding DNA as previously described (Jung‐Schroers et al., ). The resistance of isolated bacteria to antimicrobial substances was determined in an agar diffusion test by means of antimicrobial susceptibility discs (Oxoid).…”

Response of the intestinal mucosal barrier of carp (Cyprinus carpio) to a bacterial challenge by Aeromonas hydrophila intubation after feeding with β‐1,3/1,6‐glucan

“…In addition to the mucosal responses and the reduction in the total amount of bacteria in the gut, the composition of the bacterial microbiota in the gut was also altered differently by bacterial challenge depending on the feed regime prior to bacterial intubation. Dietary β‐glucan has been previously shown to impact the microbiota in the gut of carp (Jung‐Schroers et al., ; Kuhlwein et al., ). After feeding with MacroGard ® at 1% within the diet for a period of 2 weeks, the diversity of the intestinal microbiome of carp was higher compared to carp fed a diet without β‐glucan and it was assumed that the diverse microbiota might be more stable and thus might have a better protective capacity against infection (Jung‐Schroers et al., ).…”

“…Reverse transcription–polymerase chain reaction–denaturing gradient gel electrophoresis was used to assess species richness of the bacteria associated with the first and the second segment of the midgut of carp 12, 24, 72 and 168 hr after oral application of A. hydrophila (Adamek et al., ) with modifications (Jung‐Schroers et al., ). cDNA, pooled by time point/diet, was used as a template for each PCR.…”

Influence of a membrane‐denitrification reactor on the microbial community of an aquaculture recirculation system

“…Six carp per system and time‐point were anaesthetized with 0.15 g/L of a buffered tricaine (MS222, Pharmaq, UK), and swabs were collected from mucus of skin and gills. All swabs were analysed by culturing and 16S rRNA gene sequencing for bacterial species (Jung‐Schroers et al., ). In accordance with the 16S rRNA sequences, specific primers for particular bacterial species were designed and used in a quantitative PCR analysis (Adamek et al., ; Miest, Arndt, Adamek, Steinhagen, & Reusch, ) (Supporting Information Data S4).…”

“…Six carp per system and time-point were anaesthetized with 0.15 g/L of a buffered tricaine (MS222, Pharmaq, UK), and swabs were collected from mucus of skin and gills. All swabs were analysed by culturing and 16S rRNA gene sequencing for bacterial species (Jung-Schroers et al, 2016).…”