Bioprospecting the Solar Panel Microbiome: High-Throughput Screening for Antioxidant Bacteria in a Caenorhabditis elegans Model.

Kristie Tanner,Manuel Porcar,Daniel Ramón,María Jesús Rodrigo,Patricia Martorell,Lorenzo Zacarías,Juli Peretó,Salvador Genovés

doi:10.3389/fmicb.2019.00986

Abstract

Microbial communities that are exposed to sunlight typically share a series of adaptations to deal with the radiation they are exposed to, including efficient DNA repair systems, pigment production and protection against oxidative stress, which makes these environments good candidates for the search of novel antioxidant microorganisms. In this research project, we isolated potential antioxidant pigmented bacteria from a dry and highly-irradiated extreme environment: solar panels. High-throughput in vivo assays using Caenorhabditis elegans as an experimental model demonstrated the high antioxidant and ultraviolet-protection properties of these bacterial isolates that proved to be rich in carotenoids. Our results suggest that solar panels harbor a microbial community that includes strains with potential applications as antioxidants.

Highlights

Antioxidants are molecules that can protect cells against oxidative stress
Culturing of the solar panel samples yielded a high amount of colony-forming pigmented microorganisms on all three media (LB, Reasoner’s 2A (R2A), and Marine Agar (MA)) as previously described (Dorado-Morales et al, 2016), the isolates growing on Luria-Bertani medium (LB) media displayed more intense pigmentation
Fungal growth was much lower on LB medium than on R2A or MA, facilitating the isolation of pure bacterial cultures from samples grown on LB medium rather than from the other two media

Summary

Introduction

Antioxidants are molecules that can protect cells against oxidative stress They can play a protective role against the biological damage derived from an excessive cellular production of reactive oxygen species (ROS). ROS are unstable metabolites of molecular oxygen (i.e., superoxide radical, hydroxyl radical, or hydrogen peroxide) that are constantly generated in the cells as by-products of normal aerobic metabolism, but whose levels can increase under certain stress situations (for example, alcohol consumption, smoking, or exposure to environmental pollutants) and become harmful for the cell (Al-Gubory, 2014; Rahal et al, 2014; Zorov et al, 2014; Chen et al, 2015). The discovery of new antioxidants from natural sources (i.e., plants or microorganisms) is of high interest for the pharmacological and food industries (Finley et al, 2011; Lin et al, 2014). The search for novel natural molecules with biotechnological applications is known as bioprospecting and, in the past, microorganisms have proved to be rich sources of natural products that have been

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