Abstract
Changes in gut microbial composition over time in rainbow trout fed differentially processed diets supplemented with the filamentous fungi Neurospora intermedia were investigated in a 30-day feeding trial. Fish were fed a reference diet, non-preconditioned diet (NPD), or preconditioned (heat-treated) diet (PD), with the same inclusion level of N. intermedia in diets NPD and PD. Gut microbiota were analyzed on day 0, 10, 20, and 30. Gut microbial composition was similar for all diets on day 0, but was significantly different at day 10 and day 20. On day 30, the gut again contained similar communities irrespective of diet. The overall gut microbiota for each diet changed over time. Abundance of Peptostreptococcus and Streptococcus was higher in the initial days of feeding in fish fed on commercial diet, while a significant increase in lactic acid bacteria (Lactococcus lactis) was observed on day 30. Feed processing (preconditioning) did not contribute largely in shaping the gut microbiome. These results indicate that dietary manipulation and duration of feeding should be considered when evaluating gut microbial composition in cultured fish. A minimum 30-day feeding trial is suggested for gut microbiome, host and diet interaction studies.
Highlights
Single-cell proteins such as microalgae, bacteria, and fungi are microbial protein sources that represent potential alternatives as fish feed ingredients (Nalage et al, 2016)
A total of 5,961 operational taxonomic units (OTUs) were obtained after excluding Mycoplasma OTUs, and bacterial OTU abundance was dominated by two phyla, Firmicutes (58%) and Proteobacteria (15%) (Figure 1B)
The principal coordinate analysis (PCoA), analysis of similarity (ANOSIM), and Similarity percentage analysis (SIMPER) results demonstrated that the overall differences seen in gut microbial community were based on type of diet and feeding period
Summary
Single-cell proteins such as microalgae, bacteria, and fungi are microbial protein sources that represent potential alternatives as fish feed ingredients (Nalage et al, 2016). The nutritional value of filamentous fungal biomass derives from its high protein content, fatty acid composition, and presence of other nutrients such as vitamins, minerals, anti-oxidants, and immune stimulant components (Karimi et al, 2019a). Despite these attractive nutritional properties of filamentous fungal biomass, few studies have explored its use as a fish feed ingredient. Using nuclear magnetic resonance (NMR) spectroscopy, Abro et al (2014) investigated changes in the metabolism of Arctic charr (Salvelinus alpinus) fed with filamentous fungal species Rhizopus oryzae. In another study, Vidakovic et al (2016) used intact and extracted baker’s yeast (Saccharomyces cerevisiae) and Rhizopus oryzae as separate diet ingredients and evaluated the effects on digestibility and intestinal barrier function in Arctic charr
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
