Seventeen different media known to support the growth and isolation of members of the class Actinobacteria were evaluated as selective isolation media for the recovery of this microbial group from marine sediments samples collected in the Gulf of California and the Gulf of Mexico. A general selective isolation procedure was employed for six sediments and nearly 300 actinomycetes were recovered from the selective isolation plates. Full 16S rRNA gene sequencing revealed that the isolates belonged to several actinobacterial taxa, notably to the genera Actinomadura, Dietzia, Gordonia, Micromonospora, Nonomuraea, Rhodococcus, Saccharomonospora, Saccharopolyspora, Salinispora, Streptomyces, "Solwaraspora" and Verrucosispora. Previous works on marine sediments have been restricted to the isolation of members of the genera Micromonospora, Rhodococcus and Streptomyces. This study provides further evidence that Actinobacteria present in marine habitats are not restricted to the Micromonospora-Rhodococcus-Streptomyces grouping. Indeed, this first systematic study shows the extent of actinobacterial diversity that can be found in marine sediments collected in Mexico and probably, worldwide.

This study collates and reviews the state of the art in the phenomenon of atypical pelagic Sargassum influxes in the coastline of the Mexican Caribbean, focusing on projects, studies and initiatives that have been conducted in the country for a decade. We integrated multisectoral and multidisciplinary knowledge and identified gaps and strengths in current knowledge. Initiatives and projects conducted in Mexico are numerous, diverse and valuable. However, interdisciplinary and transdisciplinary research and interinstitutional coordinated actions in the medium- and long-term are still lacking. Because of this, there is an imbalance of actions in different knowledge areas that prevents this phenomenon from being addressed in a comprehensive way. Furthermore, the funding opportunities for Sargassum research projects and other initiatives seem to respond to the events of massive influxes, without continuity or long-term planning. Attention is mainly focused on urban and touristic areas, so impacts to rural or uninhabited zones are unknown. This review represents a stepping-stone towards an integrated multisectoral effort to shift the perspective from Sargassum being a “national problem” to a “national resource,” considering and fully understanding the ecological importance of this macroalgae as a floating ecosystem and its potential as an economic resource once it massively arrives in Mexican coastal areas.