Transformation of microbiota of fish intestines and gills against the background of molybdenum oxide nanoparticles in environment

Abstract

This work is aimed at the evaluation of transformation of microbiota of Danio rerio intestines and gills under the impact of MoO3NPs, which corresponds to the existing level of studies using this model. The composition of the microbial community of Danio rerio was studied after nanoparticles of MoO3 (MoO3NPs) were administered into the environment in amount of 0.2 mg/dm3 within 7 days (Group II), in amount of 0.4 mg/dm3 within 14 days (Group III) in the form of lyosols with fish feed. MoO3NPs were not added to the reference group I; the procedure was comprised of the following: sampling, isolation, cleaning, measurement of DNA concentrations, polymerase chain reaction, validation and normalization of libraries with subsequent sequencing on the basis of high-performance sequenator (MiSeq Illumina, USA). Dose-dependent influence of MoO3NPs on microbiota transformation of intestines and gills has been estimated. Nanoparticles modify the composition of the microbiota by reducing the amount of symbionts participating in vital activity of macro-organism. Gills’ microbiota is modified to a greater extent, and the increased occurrence of Actinobacteria phylum has been detected with significant difference in Group III. In fish intestines of Group II Cetobacterium somerae is the significant species. In Group III, representatives of Acinetobacter and Staphylococcus genuses have been identified, and the increase in fraction of Gram-positive microflora has been observed. The results evidence the violation of equilibrium in microbiota of intestines and gills and suppression of protecting mechanisms which usually prevent colonization by foreign microflora. Penetration of MoO3NPs into organism can influence the fish intestinal and respiratory systems and health.