Intestinal Microbiocenosis Disorders in Danio rerio (Hamilton, 1882) and Inhibition of Protective Mechanisms under Nickel-Containing Nanoparticle-Induced Effects

Abstract

The state of the antioxidant system and the intestinal microbiocenosis in Danio rerio (Hamilton, 1822) have been studied with the use of nickel and its oxide nanoparticles released into environments. It is revealed that the nanoparticle-induced toxic effect causes oxidative stress, followed by restructuring of the intestinal microbiocenosis and inhibiting the protective mechanism. A low loading dose and a short period of exposure of the test object to the nickel nanoforms activate the antioxidant defense system of the body in response to the free radical evolution. Chronic conditions and high doses exhaust the antioxidant system under the effect of free-radical hyperproduction during oxidative stress. A change in the microorganism species diversity is ascertained; for instance, Rhodobacter and Methylobacterium replace Citrobacter and Enterobacter, respectively, with the introduction of the nickel oxide nanoparticles, while Bacillus, Acinetobacter, and Rhodobacter replacement occurs with the introduction of nickel nanoparticles. Therefore, the transient microorganisms tend to replace the normal intestinal flora. An increase in the environmental total amount of nickel in the nanoparticle form results in its accumulation in the body of hydrobionts under the effect of the induction of chronic conditions.