Diversity and Functions of Epilithic Riverine Biofilms

Daniel Pineda-Mora,José Luis Aguirre-Noyola,Jeiry Toribio-Jiménez,Paul Alexander Arp,Jesús Carlos Ruvalcaba-Ledezma,Maria Teresa Leal-Ascencio,Hugo Gildardo Castelán-Sánchez,Ana Laura Juárez-López

doi:10.1007/s11270-020-04692-x

Abstract

This article relates epilithic dry- and wet-seasonal bacterial biofilm composition to water quality along Río de la Sabana near Acapulco, Mexico. Samples were taken from various locations including nearly pristine upland locations, adjacent to residential floodplain developments, and immediately upstream from an estuarine lagoon. Bacterial composition was identified through sequential DNA analysis at the phylum, class, order, and family levels, with most of these categorized as heterotrophs, autotrophs, denitrifiers, nitrogen fixers, pathogens, and/or potential bioremediators based on generalized literature-sourced assignments. The results were interpreted in terms of location by extent of effluent pollution, and by dry versus wet seasonal changes pertaining to biofilm composition, related bacterial functions, and the following water quality parameters: temperature, pH, dissolved oxygen, biological and chemical oxygen demand, fecal and total bacteria counts, methylene blue active substances, electrical conductivity, and nitrite, nitrate, ammonium, sulfate, and phosphate concentrations. It was found that epilithic bacterial biofilm diversity was richest during the wet season, was more varied in abundance along the upland locations, and was dominated by Proteobacteria and Bacteroidetes with bioremediation and pathogen functions along effluent-receiving river locations. Low-abundance families associated with anaerobic and denitrifying functions were more prevalent during the wet season, while low-abundance families associated with aerobic, N2-fixing and pH-elevating functions were more prevalent during the dry season.

Highlights

This article reports on epilithic bacterial biofilm composition, functions, and changes along Río de la Sabana as it flows north to south east of Acapulco, Mexico
Biofilms are densely populated and self-stabilizing microbiomes (Besemer 2015; Peipoch et al 2015; Findlay and Battin 2016; Nicholls and Crompton 2017) involving algae, diatoms, fungi, bacteria, and protozoa, all enveloped in an extracellular polymeric substance matrix (EPS) on biotic and/or abiotic surfaces (Nadell et al 2009; Villeneuve et al 2013; Nadell et al 2016)
These changes can be revealed in terms of operational taxonomic units (OTUs) using generation sequencing (NGS) Deoxyribonucleic acid (DNA) technologies (Ghiglione et al 2014; Tan et al 2015; Pawlowski et al 2018)

Summary

Introduction

This article reports on epilithic bacterial biofilm composition, functions, and changes along Río de la Sabana as it flows north to south east of Acapulco, Mexico. Several studies have stressed that microbial biofilm compositions are subject to physical, chemical, and biological changes in water flow and quality (Pesce et al 2010; Montuelle et al 2010; Tlili et al 2011; Baek et al 2013; Langenheder et al 2016; Bouchez et al 2016; Hu et al 2017) These changes can be revealed in terms of operational taxonomic units (OTUs) using generation sequencing (NGS) DNA technologies (Ghiglione et al 2014; Tan et al 2015; Pawlowski et al 2018). The emphasis is on epilithic biofilms because their bacterial composition would directly be affected by locational changes in water quality, varying flow rates, and desiccating exposure incidences

Methods

Discussion

Conclusion