Degradación de oxalato por bacterias oxalotróficas asociadas a plantas del géneroOxalis sp en regiones Andinas del departamento de Nariño, ColombiaOxalate degradation by oxalotrophic bacteria associated with plants of the genus Oxalis sp in the Andean region of the department of Nariño, Colombia ResumenIntroducción: El ácido oxálico (H 2 C 2 O 4 ) y las sales de oxalato son sustancias altamente oxidadas y consideradas tóxicas para algunos sistemas biológicos, incluido el humano, no obstante, pueden ser utilizadas como fuente de carbono y energía por algunas comunidades bacterianas, denominadas oxalotróficas, las cuales por su capacidad metabólica forman parte de la ruta biogeoquímica oxalato-carbonato (OCP, oxalate-carbonate pathway). Objetivo: Aislar y caracterizar bacterias oxalotróficas a partir de plantas del género Oxalis sp., de zonas alto-andina de Nariño-Colombia. Materiales y métodos: Se recolectaron muestras de suelo rizosférico de plantas oxalogénicas que fueron analizadas con parámetros fisicoquímicos y se utilizó un medio selectivo Schlegel para el aislamiento de bacterias oxalotróficas. Resultados: Las bacterias aisladas en medio selectivo Schlegel fueron caracterizadas bioquímicamente como: (Serratia fonticola, Bacillus amyloliquefaciens, Bacillus subtilis, Bacillus vallismortis y Bacillus cereus). Estas especies fueron capaces de degradar oxalato e incrementar el pH producto de la degradación. Conclusión: Este tipo de bacterias pueden ser estudiadas en trabajos complementarios para evaluar su potencial como biofertilizantes y/o alternativas de bioremediación en suelos ácidos. El estudio a pesar de ser indicativo a nivel biológico, puede en un futuro y con base en mayores soportes en investigación, tornarse en una promisoria aplicación para reducir el oxalato de calcio en los alimentos de consumo diario que presentan un renglón de importancia agrícola en la región, potencialmente dañinos para la función renal. Universidad y Salud[70] AbstractIntroduction: Oxalic acid (H2C2O4) and oxalate salts are highly oxidized substances, which are considered as toxic for some biological systems, including the human being; however, they can be used as a source of carbon and energy for some bacterial communities called oxalotrophic which are part of the so called oxalate-carbonate geochemistry pathway (OCP) due to its metabolic capacity. Objective: The aim of this research was to isolate and characterize oxalotrophic bacteria from plants of the genus Oxalis sp. in the high-andean zone of the department of Nariño, Colombia. Materials and methods: Samples of rhizosphere soil from oxalogenic plants were analyzed with physicochemical parameters and a Schlegel selective medium was used to isolate oxalotrophic bacteria. Results: The isolated bacteria through Schlegel selective medium were identified biochemically as: (Serratia fonticola, Bacillus amyloliquefaciens, Bacillus subtilis, Bacillus vallismortis and Bacillus cereus). The identified species play an important role in the rhizosphere soil, principally for the ...

Abstract. Introduction. Polyhydroxyalkanoate (PHA) is a useful, carbon-neutral polymer that can be produced from renewable carbon sources by microorganisms, making it a sustainable and environmentally friendly material. Currently, production of the biopolymer is not competitive in terms of cost and yield; however, production by different bacterial strains may provide economic viability, especially since substituting biodegradable plastics for nondegradable synthetic plastics has drawn interest from both academia and the commercial world. Objective. The aim of this work was to describe the isolation and partial characterization of PHA-producing bacteria isolated from five sites (gas stations) in coastal regions of Tumaco Island, Nariño-Colombia, and classify different physicochemical parameters of granules that show the production of the biopolymer. Materials and methods. A viable colony staining method using Nile red was used to preliminarily screen for PHA-producing bacteria. Colonies were isolated, characterized via biochemical, microbial, and molecular methods, and tested for antimicrobial susceptibility and fermentation. Results. More than thirty-eight strains were identified as potential PHA-positive isolates from this screening approach but, just one isolated was viable in PHA production (T2-25A). All isolates were resistant to metronidazole, ampicillin, trimethoprim sulfamethoxazole, cephalothin, ceftriaxone, and cefazolin, and 27.3 % of isolates were resistant to novobiocin. Conclusions. One promising PHA-producing isolate was obtained. Nevertheless, this information will complement future studies of the conditions necessary to produce PHA. Moreover, antibiotic resistance data have attracted attention, especially because of the origin of the source waters of the isolates.

<p class="ABSTRACT">Oxalate is a highly oxidized organic acid anion used as a carbon and energy source by oxalotrophic bacteria. Oxalogenic plants convert atmospheric CO2 into oxalic acid and oxalic salts. Oxalate-salt formation acts as a carbon sink in terrestrial ecosystems via the oxalate-carbonate pathway (OCP). Oxalotrophic bacteria might be implicated in other carbon-storage processes, including the synthesis of polyhydroxyalkanoates (PHAs). More recently, a variety of bacteria from the Andean region of Colombia in Nariño have been reported for their PHA-producing abilities. These species can degrade oxalate and participate in the oxalate-carbonate pathway. The aim of this study was to isolate and characterize oxalotrophic bacteria with the capacity to accumulate PHA biopolymers. Plants of the genus <em>Oxalis</em> were collected and bacteria were isolated from the soil adhering to the roots. The isolated bacterial strains were characterized using biochemical and molecular biological methods. The consumption of oxalate in culture was quantified, and PHA production was monitored in batch fermentation. The polymeric composition was characterized using gas chromatography. Finally, a biosynthetic pathway based on our findings and on those from published sources is proposed. Strains of <em>Bacillus</em> spp. and <em>Serratia</em> sp. were found to metabolize calcium oxalate and synthesize PHA.</p>