Hydrogen and Carbon Monoxide-Utilizing Kyrpidia spormannii Species From Pantelleria Island, Italy.

Carmen Hogendoorn,Nunzia Picone,Paola Quatrini,Mike S. M. Jetten,Antonina L. Gagliano,Huub J. M. Op den Camp,Arjan Pol,Walter D’Alessandro,Theo A. van Alen,Geert Cremers

doi:10.3389/fmicb.2020.00951

Abstract

Volcanic and geothermal areas are hot and often acidic environments that emit geothermal gasses, including H2, CO and CO2. Geothermal gasses mix with air, creating conditions where thermoacidophilic aerobic H2- and CO-oxidizing microorganisms could thrive. Here, we describe the isolation of two Kyrpidia spormannii strains, which can grow autotrophically by oxidizing H2 and CO with oxygen. These strains, FAVT5 and COOX1, were isolated from the geothermal soils of the Favara Grande on Pantelleria Island, Italy. Extended physiology studies were performed with K. spormannii FAVT5, and showed that this strain grows optimally at 55°C and pH 5.0. The highest growth rate is obtained using H2 as energy source (μmax 0.19 ± 0.02 h–1, doubling time 3.6 h). K. spormannii FAVT5 can additionally grow on a variety of organic substrates, including some alcohols, volatile fatty acids and amino acids. The genome of each strain encodes for two O2-tolerant hydrogenases belonging to [NiFe] group 2a hydrogenases and transcriptome studies using K. spormannii FAVT5 showed that both hydrogenases are expressed under H2 limiting conditions. So far no Firmicutes except K. spormannii FAVT5 have been reported to exhibit a high affinity for H2, with a Ks of 327 ± 24 nM. The genomes of each strain encode for one putative CO dehydrogenase, belonging to Form II aerobic CO dehydrogenases. The genomic potential and physiological properties of these Kyrpidia strains seem to be quite well adapted to thrive in the harsh environmental volcanic conditions.

Highlights

Volcanic and geothermal areas represent the result of the dynamics involving the deeper layers of the earth and resulting in the emission of several gases from volcanic soils
We focused on H2 and CO-utilizing bacteria from the Favara Grande geothermal site on Pantelleria Island, Italy
We show that the genomic potential and physiological properties of the two Kyrpidia strains seem very suited to thrive in harsh volcanic conditions

Summary

INTRODUCTION

Volcanic and geothermal areas represent the result of the dynamics involving the deeper layers of the earth and resulting in the emission of several gases from volcanic soils. Gagliano et al (2016) showed that 99% of the sequences obtained at the FAV1 site at the geothermal soils of the Favara Grande (Pantelleria Island) could be assigned to four main phyla: Proteobacteria, Firmicutes, Actinobacteria and Chloroflexi. We focused on H2 and CO-utilizing bacteria from the Favara Grande geothermal site on Pantelleria Island, Italy These hot and acidic soils are characterized by H2 (5-168,000 ppm) and CO (1.626 ppm) emissions (D’Alessandro et al, 2009) and in situ H2 consumption was already observed (Gagliano et al, 2016). Both H2 and CO have a high potential as electron donor for microbial growth. We show that the genomic potential and physiological properties of the two Kyrpidia strains seem very suited to thrive in harsh volcanic conditions

MATERIALS AND METHODS

RESULTS AND DISCUSSION

CONCLUSION

DATA AVAILABILITY STATEMENT