Despite that evaluation of the gut microbiota can be dates to the late 1920`s and early 1930`s (Reed and Spence, 1929; Stewart, 1932; Gibbons, 1933), controversy still existed in the 70s about the existence and role of indigenous microbiota in fish gastrointestinal (GI) tract (Ringø et al., 2016). However, today it is generally accepted that fish gut microbiome, which include e.g., bacteria, fungi and yeast are modulated by dietary components, age, gender, health status and environmental factors (Ringø et al., 2016; Egerton et al., 2018; Bates et al., 2022). The microbiome plays a crucial role in GI development, digestive function, maintaining mucosal tolerance, barrier functions and in the maintenance of its homeostasis, enhance the immune response, provide protection against exogenous microorganisms and diseases (e.g., Rawls et al., 2004; Rawls et al., 2006; Wang et al., 2018; Li et al., 2019), development of metabolic syndrome (Clément, 2011), vitamin synthesis (Rowland et al., 2018), the gut-brain axis (Cryan and O`Mahony, 2011; Butt and Volkoff, 2019), as well as effect on flesh color (Nguyen et al., 2020). Furthermore, several reports highlighted the ability of the gut microbiota to interact with the host’s tissue, controlling its energy metabolism, contributing to variations in body weight, fat distribution, insulin sensitivity, and lipid metabolism (e.g., Zhang and Zhang, 2013; Falcinelli et al., 2015; Kim et al., 2018).
Gatesoupe (1994) published a pioneer study on the effect of lactic acid bacteria supplementation on the improved resistance of turbot (Scophthalmus maximus) larvae against Vibrio. Five years later, published Ringø and Birkbeck (1999) an overview of bacterial species isolated from the GI tract of early developed freshwater and marine species. Since then, numerous studies on larvae and gut bacteria have been published. However, to obtain a sustainable aquaculture it is of high importance to clarify one important bottleneck, proper rearing of the early teleost larvae, their gut microbiota, and the connection between commensal and opportunistic bacteria in larval gut (e.g., Ringø and Birkbeck, 1999; Vadstein et al., 2013; Vadstein et al., 2018; Pan et al., 2022; Vestrum et al., 2022). Furthermore, to achieve successful larval rearing more information is needed on the interactions between gut-, skin- and gill microbiota, along with microbial evaluations of tank biofilms and water.
Modern technology by recirculating aquaculture systems (RASs) was introduced in mid 1990s, and since then numerical studies have been published (e.g., Kroeckel et al., 2012; Xiao et al., 2019), and how RASs affect the gut microbiota (e.g., Dehler et al., 2017; Minich et al., 2020), but as less information is available on larvae (Deng et al., 2021) this topic merits further investigations.
To understand the microbiota participation, zebrafish (Danio rerio) has rapidly become the well-recognised animal model to study microbe-host interactions (Nadal et al., 2020; Zhong et al., 2022), and today evaluation of gnotobiotic protocols for aquaculture fish are available. The GI tract bacteria in fish is generally divided into; the allochthonous, the GI lumen bacteria, and the autochthonous, those who adhere and colonise the mucosal surface. This is visualised in the review of Ringø et al. (2003). However, the molecular mechanisms of the interactions between commensal microbes and host are still poorly understood in fish (Yang et al., 2019). Future studies should use gnotobiotic zebrafish technology, combined with multi-omics analysis, RNA interference and other techniques to further explore these problems.
It is well known that fish possess not all essential enzymes to handle with the dietary challenges of aquaculture production. However, the GI microbiota with probiotic potential secrete various digestive and degradation enzymes to degrade a variety of nutritional substrates, thus, use of probiotics in diet can provide a chance of possibility to use different sources of carbohydrates as animal energy source. Further studies are needed to illustrate which and how commensal microbes regulate carbohydrate metabolism, the common characteristics of specific bacteria in regulating carbohydrate metabolism and the possible mechanisms in fish.
To conclude, studies included in the Research Topic Composition, Functions and Modulation of Gut Microbiota in Maricultural Animals highlighted the importance of the gut microbiota. Future studies should focus on modulation of gut microbiota and how these changes affect fish physiology, nutrition, homeostasis, and disease resistance. Even though our knowledge on the importance of the fish gut microbiota has increased significantly during the last two decades, there still a long way to go, and the topic is probably a never-ending story.
Funding
This work was supported by the National natural science foundation of China (32072990), Science and Technology Major/Special Project of Fujian Province (2021NZ029022), Xiamen Marine and Fisheries Development Fund (19CZP018HJ04)
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Conflict of interest
The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.
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Summary
Keywords
gut microbiota, composition, functions, modulation, maricultural animals
Citation
Sun Y-Z, Zhang Y and Ringø E (2022) Editorial: Composition, functions and modulation of gut microbiota in maricultural animals. Front. Mar. Sci. 9:985012. doi: 10.3389/fmars.2022.985012
Received
03 July 2022
Accepted
10 August 2022
Published
25 August 2022
Volume
9 - 2022
Edited and reviewed by
Yngvar Olsen, Norwegian University of Science and Technology, Norway
Updates
Copyright
© 2022 Sun, Zhang and Ringø.
This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
*Correspondence: Yun-Zhang Sun, jmusunyunzhang@163.com; Einar Ringø, einar.ringo@uit.no
This article was submitted to Marine Fisheries, Aquaculture and Living Resources, a section of the journal Frontiers in Marine Science
Disclaimer
All claims expressed in this article are solely those of the authors and do not necessarily represent those of their affiliated organizations, or those of the publisher, the editors and the reviewers. Any product that may be evaluated in this article or claim that may be made by its manufacturer is not guaranteed or endorsed by the publisher.