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The objective of PROBISOLE is to develop new feeding protocols for the cultivation of Senegalese sole (Solea senegalensis) that contributes to overcoming the reproductive dysfunction of males born and bred in captivity. If achieved, this project would make progress in overcoming one of the bottlenecks that affects the reproductive control of this species. More specifically, the effect that the ingestion of probiotic bacteria strains can have on reproductive quality parameters in the male will be studied using different time frames of intake in early stages of the species’ culture. Globally, this project aims to promote technological development and innovation in the aquaculture sector.

Specific objectives of the project :

1. To optimize the bioencapsulation of Pediococcus acidilactici MA 18/5M in Artemia fransciscana nauplii.
2. Study and analysis of the development of the gonads in Solea senegalensis during juvenile culture.
3. To study the effect of probiotic intake on two early time frames of the Senegalese sole life cycle (Time frame 1 (larval): 0-90 days; Time frame 2 (juvenile): 0-10 months) on genes regulating steroid hormone synthesis and genes related to gametogenesis.
4. To study the effect of probiotic intake on two early time frames of the life cycle of Senegalese sole (Time frame 1 (larval): 0-90 days; Time frame 2 (juvenile): 0-10 months) at the biometric level and on immune response and growth genes.
5. To disseminate the species and publicize the importance of marine aquaculture as a national strategic sector.

The effect of continued intake of the probiotic Pediococcusacidilactici MA 18/5M in the early stages of development of Solea senegalensis on reproductive quality
parameters will be studied, focusing attention on the gonadal development of the male (who presents reproductive dysfunction when born and bred in captivity). To this end, activities will be carried out to optimize bacterial bioencapsulation in artemia nauplii, sole progeny will be launched in optimal conditions similar to those existing in the industry, two experimental groups will be generated according to diet (control vs. probiotics) and the effect of probiotic supplementation will be analyzed in a multiparametric way. Supplemented diet evaluation activities include histological, cell proliferation, apoptosis, biometry, and gene expression studies (genes related to gametogenesis, gonadal development, immune response, and growth).

The objective of PROBISOLE has been to develop new feeding protocols for the cultivation of Senegalese sole (Solea senegalensis) that contribute to overcoming the reproductive dysfunction of males born and bred in captivity, unable to reproduce naturally in aquaculture facilities.

This project has sought to make progress in overcoming one of the bottlenecks that affects the reproductive control of this species. More precisely, the effect that the ingestion of a probiotic bacterial strain can have on parameters of reproductive quality, growth and modulation of the immune system in the early stages of the species’ culture has been studied, focusing on males.

The time frame evaluated has differentiated PROBISOLE from most studies that address reproductive problems, in which sexually mature specimens are usually used and do not take into account possible early acquired dysfunctions.

It has been intended to give a new approach to probiotic supplementation as a biotechnological tool in the reproductive improvement in this species of high commercial interest. To this end, a realistic experimental design has been carried out on a semi-industrial scale, using a strain approved by EFSA for use in aquaculture.

After the development of the project, it can be concluded that the research carried out during the year of implementation of the PROBISOLE project allows to prove, through its results, that prolonged intake (0-12 months of age) achieves:

1) match at the larval culture stage and, up to 90 days after hatching, the growth rates of the standard protocols,

2) the promotion of the immune system of the specimens against one of the common pathologies of the cultivation of this species in the facilities, the rot of the tail,

3) a better specific growth rate in tanks fed with probiotic-supplemented feed and gene expression data, supporting this observation,

4) Differences in gene expression of the gene, a key in spermatogenesis in developing testicular samples

5) preliminary indications at the tissue level of a positive impact of probiotic intake on testicular development.

Overall, this project lays the groundwork for considering the studied probiotic strain as a useful biotechnological tool that can be easily transferred to aquaculture companies to optimize the reproduction of Senegalese sole in the future. After the end of the project, the stock of specimens will be maintained until they reach sexual maturity to continue collecting evidence.

The results obtained during the project were presented in October 2021 at the European Aquaculture Congress 2021, held in Madeira, the main scientific event focused on this sector in Europe. In addition to participating in this type of specialized forums, the research team has carried out multiple sessions of scientific dissemination to different groups of non-specialized public within the framework of workshops, visits to the IEO facilities and sessions in educational centers in which the importance of aquaculture has been transferred at a national and international level. it has brought the species closer to the general public and the objectives and scientific results obtained have been explained.