BIOSORPTION OF LEAD(II) IONS BY DEAD BACTERIAL BIOMASS ISOLATED FROM MINE WATER

El plomo y sus diferentes formas químicas se han utilizado ampliamente en la industria durante los últimos años y el resultado es la alta contaminación detectada en el agua y el suelo. Se aislaron microorganismos resistentes al plomo (II) de muestras líquidas recolectadas en Mina Asientos, Cochabamba-Bolivia. Se aislaron once cepas en medio sólido con 200 ppm de Pb (II) y se seleccionaron 4 cepas para remoción de metales en muestras líquidas, una cepa presentó los valores de remoción de Pb (II) más altos para 250 ppm de Pb (II). La cepa seleccionada designada como MA-4 se sometió a estudios filogenéticos y mostró una similitud de secuencia del 99,9% con Pseudomonas monteilii. La biosorción sigue los modelos de isotermas de Langmuir y Freundlich, con valores de qmax y Kf de 166,67 y 11,09, respectivamente. Estos resultados implicaron una fuerte capacidad de unión a la biomasa muerta y su potencial aplicación en el proceso de biosorción.

Protection of Eggplant Seed Germination from the Inhibitory Effect of o-Cresol by Bioaugmentation of Soil with Pseudomonas monteilii Strain

Bulk production and widespread end use of cresol isomers in various industrial processes result in their ubiquitous presence in the environment. Cresols are highly toxic to both fauna and flora and are included in the list of priority pollutants. This study presents the effect of o-cresol on germination of 10 different vegetable crop seeds as tested by the standard Filter Paper Method. The seeds of eggplant and long-podded cowpea were found to be highly sensitive. The most sensitive eggplant seeds were subjected to further studies in soil. Germination percentage and the seedling vigor were drastically reduced in the presence of o-cresol even at a concentration as low as 50 mg kg−1 soil. A number of abnormalities in the seedlings such as stunted root and shoot growth, non-emergence of primary leaves, and negative geotropic growth were observed. Standard 2, 3, 5-tetrazoliumtrichloride test showed marked reduction in the viability of eggplant seeds proportionate to the concentration of o-cresol (0 through 200 mg L−1) they were exposed to, which reached zero at 175 mg o-cresol L−1, indicating the inhibition of the respiratory enzymes of the seeds. Contrary to earlier reports on the effect of phenolics on the hydrolytic enzymes of germinating seeds, in the present case an enhanced activity of amylase was observed in the presence of o-cresol (50 and 150 mg kg−1 soil), whereas the protease activity was partially inhibited at higher concentration. The inhibition of seed germination by o-cresol was revoked by bioaugmentation of the soil with the cresol-degrading Pseudomonas monteilii S-CSR-0014 (2.3 x 108 CFU g−1 wet soil) enabling normal seed germination and seedling growth. The inoculated bacterium degraded 50 and 150 mg o-cresol kg−1 soil efficiently, with concomitant growth. It can be concluded that by bacterial bioaugmentation of o-cresol-contaminated soils the inhibition of germination of crop seeds could be eliminated effectively enabling healthy seedling growth.

Emergence of clinical isolates of Pseudomonas asiatica and Pseudomonas monteilii from Japan harbouring an acquired gene encoding a carbapenemase VIM-2

Pseudomonas asiatica and Pseudomonas monteilii , belonging to the Pseudomonas putida phylogenetic group, are occasionally isolated from clinical samples, partly because they are often misidentified as P. putida in clinical laboratories. There are five reports describing carbapenem-resistant clinical isolates of these species. Carbapenem-resistant strains of P. asiatica and P. monteilii were isolated from stool samples. These isolates were sequenced using Illumina MiSeq and reidentified using average nucleotide identity (ANI) based on comparisons of their whole-genome sequences using the OrthoANI algorithm. The clonal relatedness of the isolates was assessed by pulse-field gel electrophoresis (PFGE). The size of plasmids conveying bla VIM-2 was examined by Southern blotting. A total of six carbapenem-resistant clinical isolates of P. asiatica (two isolates) and P. monteilii (four isolates) were obtained from stool samples from five patients in a Japanese hospital. All isolates harboured blaVIM-2 . The two isolates of P. asiatica had a different pattern in the PFGE analysis, with both having a 23 kb plasmid. Of the four isolates of P. monteilii with similar patterns in the PFGE analysis, three had 320 kb plasmids and one had a 240 kb plasmid. The genetic environments of the 320/240 kb and 23 kb plasmids differed. The results strongly indicated that carbapenem-resistant P. asiatica and P. monteilii producing metallo-β-lactamase are emerging in Japan. This is the first report of carbapenem-resistant P. asiatica and P. monteilii in Japan.