The first description of the bacterial diversity of anisakids reveals the human influence in its extension to fish for consumption.
An interdisciplinary team in Spain led by the National Museum of Natural Sciences (MNCN-CSIC), of the Higher Council for Scientific Research (CSIC), has made the first detailed description of the bacterial diversity (microbiota) associated with anisakids.
These nematodes are parasites that pose a risk to public health (especially the genus Anisakis), acting as infectious agents that cause allergies and transmitters of other pathogens that can cause problems in their hosts, fish, and also in humans.
Specifically, the study found that there are at least 1,803 species of bacteria in the digestive tract of these nematodes and some of them are symbionts. These are bacteria of marine and terrestrial environmental origin, as well as bacteria of human origin. The presence of some of them is related to the contamination of the seas and the manipulation of fish by human beings.
The work, published in the magazine Microorganism, has focused on the analysis of the rRNA sequence of bacteria present internally andn larvae of two genera of anisakids (Anisakis Y Pseudoterranova) present in 111 fish caught in the North Atlantic area.
Among the species are fish such as conger eel, hake, cod or monkfish, widely consumed in Spain. The study, which includes a description from the taxonomic level of genus to phylum, has been able to verify, for the first time, that there is an extraordinarily high internal bacterial diversity.
“The high degree of diversity led us to the hypothesis that the bacterial communities associated with these nematodes develop independently of what could be considered a priori as the main influencing variables: the host fish and the specific species of anisakid. We have verified that There are no significant differences between the type of bacteria found in each species, but there are in the associations that bacteria form with each other, and these associations are indicative of the fishing areas“, said the CSIC researcher at the MNCN-CSIC and coordinator of the study, Alfonso Navas.
Scientists have described three major groups of bacteria: proteobacteria associated with temperatures up to 30 °C and those that are responsible for the decomposition of fish; bacteria present in almost any terrestrial or marine environment, and bacteria found in nematodes and in the human microbiota.
The increase in the populations of anisakids in the various species of fish studied, as well as the bacterial diversity of the anisakids that parasitize them, can only be explained, according to the scientists, by human influence on a planetary level.
The The distribution of species of these nematodes is universal and has multiple intermediate hosts, including marine species of fish commonly consumed.. The anisakids that parasitize these hosts spread their own battery of allergens through the fish meat and act as transmitters of bacteria that cause risks to human health after being ingested or affect the quality of the product.
The The relationship between bacteria and nematodes also provides relevant information about the mechanisms of bacterial virulence that are difficult to obtain with other animals.. Another aspect to highlight is that, despite knowledge of their potential, little is known about the role that nematodes play in the spread of infectious diseases in fish, especially given the cosmopolitan nature of anisakids and bacteria.