RESUMEN
An alternative for non-biodegradable oil-based plastics has been the focus of many researchers throughout the years. Polyhydroxyalkanoates (PHAs) are potential substitutes due to their biodegradable characteristic and diversity of monomers that allow different biopolymer compositions and physical-chemical properties suitable for a variety of applications. The most well-known biopolymer from this class, poly(3-hydroxybutyrate) (P3HB), is already produced industrially, but its final price cannot compete with the oil-based plastics. As a low-volume high-value bioproduct, P3HB must be produced through a cheap and abundant feedstock, with high productivity and a feasible purity process in order to become an economically attractive bioproduct. In this scenario, we report a methylotrophic strain isolated from an estuarine contaminated site identified as Methylorubrum sp. highly tolerant to methanol and with great accumulation capacity of 60% (CDW) in 48 h through a simple strategy of batch fermentation with discontinuous methanol addition that could help lower P3HB's processing costs and final price.
Asunto(s)
Metanol/farmacología , Methylobacteriaceae/efectos de los fármacos , Methylobacteriaceae/metabolismo , Polihidroxialcanoatos/metabolismo , Biotecnología , Relación Dosis-Respuesta a Droga , FermentaciónRESUMEN
16S rRNA gene sequence analysis of eight strains (BR 3299(T), BR 3296, BR 10192, BR 10193, BR 10194, BR 10195, BR 10196 and BR 10197) isolated from nodules of cowpea collected from a semi-arid region of Brazil showed 97â% similarity to sequences of recently described rhizobial species of the genus Microvirga. Phylogenetic analyses of four housekeeping genes (gyrB, recA, dnaK and rpoB), DNA-DNA relatedness and AFLP further indicated that these strains belong to a novel species within the genus Microvirga. Our data support the hypothesis that genes related to nitrogen fixation were obtained via horizontal gene transfer, as sequences of nifH genes were very similar to those found in members of the genera Rhizobium and Mesorhizobium, which are not immediate relatives of the genus Microvirga, as shown by 16S rRNA gene sequence analysis. Phenotypic traits, such as host range and carbon utilization, differentiate the novel strains from the most closely related species, Microvirga lotononidis, Microvirga zambiensis and Microvirga lupini. Therefore, these symbiotic nitrogen-fixing bacteria are proposed to be representatives of a novel species, for which the name Microvirga vignae sp. nov. is suggested. The type strain is BR3299(T) (â=âHAMBI 3457(T)).