Hermetia illucens in diets for zebrafish (Danio rerio): A study of bacterial diversity by using PCR-DGGE and metagenomic sequencing

Abstract

In the present research, bacterial diversity was studied during a 6-month feeding trial utilizing zebrafish (Danio rerio) fed Hermetia illucens reared on different substrates with an emphasis on fish gut bacterial diversity. A polyphasic approach based on viable counting, PCR-DGGE and metagenomic 16S rRNA gene amplicon target sequencing was applied. Two different H. illucens groups were reared on coffee by-products (C) or a mixture of vegetables (S). Viable counts showed a wide variability based on substrate. PCR-DGGE and Illumina sequencing allowed the major and minor bacterial taxa to be detected. Both samples of larvae and their frass reared on the S substrate showed the highest richness and evenness of bacterial communities, whereas zebrafish (ZHC) fed H. illucens reared on substrate C and zebrafish (ZHS) fed H. illucens reared on substrate S had the lowest bacterial richness and evenness. A stimulating effect of bioactive compounds from coffee by-products on the occurrence of Lactobacillaceae and Leuconostoccaceae in H. illucens reared on substrate C has been hypothesized. Zebrafish gut samples originating from the two feeding trials showed complex microbial patterns in which Actinobacteria and Alteromonadales were always detected, irrespective of the diet used. Enterobacteriaceae in fish guts were more abundant in ZHS than in ZHC, thus suggesting an influence of the bioactive compounds (chlorogenic and caffeic acids) in the substrate on Enterobacteriaceae in fish guts. ZHC showed a higher abundance of Clostridia than did ZHS, which was likely explained by stimulating activity on the bacteria in this class by the bioactive compounds contained in H. illucens reared on substrate C. An influence of the microbiota of H. illucens or insect-derived bioactive compounds on the gut microbiota of zebrafish has been suggested. The presence of bacteria consistently associated with zebrafish guts has been found irrespective of the diet, thus attesting to the likely stability of the core fish microbiota.

Animal-Origin Prebiotics Based on Chitin: An Alternative for the Future? A Critical Review

“…With respect to beneficial groups, an increase was observed in the butyrate-producing Clostridium coccoides-Eubacterium rectale cluster [71] and other lactic acid and butyrate producers [64]. Less consensus was obtained for other phyla such as Proteobacteria, that increased [64] or decreased [63] depending on the work, or Enterobacteriaceae, that also increased in Siberian sturgeon [70], whereas it decreased in zebrafish [69] supplemented in both cases with Hermetia illucens.…”

“…With respect to GC, its administration in non-diabetic subjects reduced the serum content of oxidized low-density lipoproteins, a major risk in cardiovascular diseases, the leading mortality cause in Western countries [92]. GC administration also decreased the body weight of rats [56] and mice, accompanied by a decrease in fat mass [69].…”

The Effect of Hydrolyzed Insect Meals in Sea Trout Fingerling (Salmo trutta m. trutta) Diets on Growth Performance, Microbiota and Biochemical Blood Parameters

“…molitor inclusion. Moreover, according to Osimani et al (2019) [ 100 ] the microbiota of black soldier fly may have been influenced by the feeding substrates used during the rearing process of insects. The microbiological composition of insects can be connected with the rearing methods and used substrates, which affect the microbiological value of insect meals due to secondary metabolites of bacteria and bacteriocin expression.…”

Zebrafish (Danio rerio) physiological and behavioural responses to insect-based diets: a multidisciplinary approach

“…Significance was set at p < 0.05 and all the results are presented as mean ± SD. As regards microbiome, bioinformatics analysis were performed as described by Osimani et al (2019) 18 and Zarantoniello et al (2020) 19 .…”

“…As an example, BSF contains lauric acid and chitin, which showed, at certain concentrations, anti-inflammatory and immune-boosting properties 14,15 . Additionally, BSF-based diets have been proven to increase biodiversity in fish microbiome community structure [16][17][18] , which in turn, has an important role in host metabolism, nutrition, immunity and welfare 18,19 .…”