Isolation and characterization of oxalotrophic bacteria from tropical soils

Abstract

The oxalate-carbonate pathway (OCP) is a biogeochemical set of reactions that involves the conversion of atmospheric CO2 fixed by plants into biomass and, after the biological recycling of calcium oxalate by fungi and bacteria, into calcium carbonate in terrestrial environments. Oxalotrophic bacteria are a key element of this process because of their ability to oxidize calcium oxalate. However, the diversity and alternative carbon sources of oxalotrophs participating to this pathway are unknown. Therefore, the aim of this study was to characterize oxalotrophic bacteria in tropical OCP systems from Bolivia, India, and Cameroon. Ninety-five oxalotrophic strains were isolated and identified by sequencing of the 16S rRNA gene. Four genera corresponded to newly reported oxalotrophs (Afipia, Polaromonas, Humihabitans, and Psychrobacillus). Ten strains were selected to perform a more detailed characterization. Kinetic curves and microcalorimetry analyses showed that Variovorax soli C18 has the highest oxalate consumption rate with 0.240 µM h(-1). Moreover, Streptomyces achromogenes A9 displays the highest metabolic plasticity. This study highlights the phylogenetic and physiological diversity of oxalotrophic bacteria in tropical soils under the influence of the oxalate-carbonate pathway.

Cadmium and cadmium‐tolerant soil bacteria in cacao crops from northeastern Colombia

“…Moreover, to assess oxalotrophy, the medium used was Schlegel AB + CaOx, using calcium oxalate (CaOx) as the sole carbon source, as reported previously by Bravo et al . (). The isolates were incubated at 28 ± 2°C during 2–6 days.…”

“…To assess potassium solubilization, the medium used was Aleksandrov (Parmar and Sindhu 2013) with biotite, feldspars and muscovite (Minerlab Ltda., Bogot a, CO), independently amended as nonsoluble potassium sources at 4 g l À1 each (Parmar and Singh 2013). Moreover, to assess oxalotrophy, the medium used was Schlegel AB + CaOx, using calcium oxalate (CaOx) as the sole carbon source, as reported previously by Bravo et al (2015). The isolates were incubated at 28 AE 2°C during 2-6 days.…”

Degradación de oxalato por bacterias oxalotróficas asociadas a plantas del género Oxalis sp en regiones Andinas del departamento de Nariño, Colombia

“…17 No obstante, es muy claro que son indispensables más estudios enfocados al entendimiento del metabolismo microbiano, la repercusión en la carbonatogénesis in situ en los diversos nichos tropicales de diferentes regiones de Colombia y el mejoramiento de la bioconversión, con el fin de determinar su rol en la fijación de CO2 y su utilidad marcante en la región.…”

Polyhydroxyalkanoate biosynthesis by oxalotrophic bacteria from high Andean soil

“…The role of oxalotrophic bacteria as major calcium oxalate oxidizers was recently demonstrated [12]. Conventional culture methods reveal a diverse assemblage of oxalotrophic bacteria living near the rhizospheres of Terminalia oblonga, Terminalia bellirica, and Milicia excelsa in tropical forests of Bolivia, India, and Cameroon, respectively [14]. In the intertropical zone, the OCP observed underneath certain tropical trees like iroko (Milicia excelsa) is surprisingly well developed.…”

“…T his p henomenon i s a n et c arbon t rap i n w hich t he i nitial CO 2 is atmospheric. The mainly acidic, non-calcareous soils found in tropical countries represent a significant sink for atmospheric CO 2 : at the present rate of increase, one full-grown iroko tree may stabilize the concentration of CO 2 in the air column over a 2 400 m 2 surface [9,14]. These circumstances make the rhizosphere (not a region of definable size or shape, but instead, a gradient of chemical, biological and physical properties that change both radially and longitudinally along the root) a competitive environment where microorganisms must develop strategies and mechanisms to improve their establishment, proliferation, and survival.…”