Diversity and Biotechnological Potential of Limestone and Serpentinite Microorganisms

The diversity and biotechnological potential of microorganisms cultivated from 10 micritic limestone, limestone and serpentinite (protolith harzburgite) rock samples collected in the Zlatibor Jurassic Ophiolitic Massif of western Serbia was assessed in this study. The most abundant cultivated rock bacteria belong to genera Stenotrophomonas, Arthrobacter, Bacillus, Paenarthobacter and Microbacterium, while the Archaeorhizomyces, Aspergillus, Mortierella, Termitomyces and Pleurotus were the most represented rock fungi after cultivation. All 120 rock isolates, screened on 7 lignocellulosic and plastic substrates, demonstrated the ability to grow and/or completely degrade at least 3 of the tested substrates. Ninety-five isolates (79.2%) grew on and/or degraded all tested substrates; 104 isolates (86.7%) grew on all tested plastic substrates, while 105 isolates (87.5%) grew on carboxymethyl cellulose (CMC), xylan and lignin. Twenty isolates (16.7%) demonstrated complete degradation of CMC. The majority of 32 isolates (87.5%) that were additionally screened on arabinoxylan grew on this substrate. Live dyeing of textile materials with a pigment-producing limestone isolate, identified as Arthrobacter, showed mixed results. While the process of coloration was successful, the color intensity after sterilization and washing was low. Potential applications of collected rock isolates in the biomass degradation, bioremediation of plastic-polluted geo-environments and textile dyeing should be further explored. HIGHLIGHTS • Investigated rocks are of the micritic limestone, limestone and serpentinite (protolith harzburgite) type. • Calcite is the main mineral phase in limestones, while lizardite is in serpentinites. • The most abundant cultivable rock bacteria belong to genera Stenotrophomonas, Arthrobacter, Bacillus, Paenarthobacter and Microbacterium. • Archaeorhizomyces, Aspergillus, Mortierella, Termitomyces and Pleurotus were the most represented rock fungi after cultivation. • 16.7% of screened rock microorganisms deg