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- Chryseobacterium palustre sp. nov. and Chryseobacterium humi sp. nov., isolated from industrially contaminated sedimentsPublication . Pires, Carlos; Carvalho, Maria F.; Marco, Paolo De; Magan, Naresh; Castro, Paula M. L.Two Gram-staining-negative bacterial strains, designated 3A10T and ECP37T, were isolated from sediment samples collected from an industrially contaminated site in northern Portugal. These two organisms were rod-shaped, non-motile, aerobic, catalase- and oxidase-positive and formed yellow colonies. The predominant fatty acids were iso-C15 : 0, anteiso-C15 : 0, iso-C17 : 1{omega}9c and iso-C17 : 0 3-OH. The G+C content of the DNA of strains 3A10T and ECP37T was 43 and 34 mol%, respectively. The major isoprenoid quinone of the two strains was MK-6. 16S rRNA gene sequence analysis revealed that strains 3A10T and ECP37T were members of the family Flavobacteriaceae and were related phylogenetically to the genus Chryseobacterium. Strain 3A10T showed 16S rRNA gene sequence similarity values of 97.2 and 96.6 % to the type strains of Chryseobacterium antarcticum and Chryseobacterium jeonii, respectively; strain ECP37T showed 97.3 % similarity to the type strain of Chryseobacterium marinum. DNA–DNA hybridization experiments revealed levels of genomic relatedness of <70 % between strains 3A10T and ECP37T and between these two strains and the type strains of C. marinum, C. antarcticum and C. jeonii, justifying their classification as representing two novel species of the genus Chryseobacterium. The names proposed for these organisms are Chryseobacterium palustre sp. nov. (type strain 3A10T =LMG 24685T =NBRC 104928T) and Chryseobacterium humi sp. nov. (type strain ECP37T =LMG 24684T =NBRC 104927T).
- Metal(loid)-contaminated soils as a source of culturable heterotrophic aerobic bacteria for remediation applicationsPublication . Pires, Carlos; Franco, Albina R.; Pereira, Sofia I. A.; Henriques, Isabel; Correia, António; Magan, Naresh; Castro, Paula M. L.Heavy metal-contaminated soils are a serious environmental problem. Herein, the culturable heterotrophic bacterial community present on two metal(loid)-contaminated sites in the Northern Portugal was investigated. The bacterial counts ranged from 5.96 to 7.69 and 7.04 to 7.51 (log CFUg(-1) soil) in Sites 1 and 3, respectively. The bacterial population was predominantly composed of Firmicutes, Proteobacteria, and Actinobacteria on both sites. The most represented genera in Site 1 were Bacillus (41%) and Pseudomonas (27%), whereas Arthrobacter (21%) and Pseudomonas (13%) were the most represented genera in Site 3. Several bacterial isolates showed tolerance to high concentrations of metal(loid)s, suggesting that both contaminated sites are a valuable source of metal(loid)-tolerant bacteria, which may be further used in bioremediation and/or phytoremediation processes.
- Assessment of rhizospheric culturable bacteria of Phragmites australis and Juncus effusus from polluted sitesPublication . Pereira, Sofia I. A.; Pires, Carlos; Henriques, Isabel; Correia, António; Magan, Naresh; Castro, Paula M. L.This study aimed at the isolation and characterization of metal(loid)-tolerant bacteria from the rhizosphere of Phragmites australis and Juncus effusus plants growing in two long-term contaminated sites in Northern Portugal. Site 1 had higher contamination than Site 3. Bacteria were isolated using metal(loid)-supplemented (Cd, Zn, and As) media. Isolates were grouped by random amplified polymorphic DNA and identified by 16S rRNA gene sequencing. Strains were also examined for their metal(loid) tolerance. The counts of metal(loid)-tolerant bacteria were higher in Site 1 and ranged between log 7.17 CFU g(-1) soil in As-containing medium and log 7.57 CFU g(-1) soil in Zn-containing medium, while counts at Site 3 varied between log 5.33 CFU g(-1) soil in Cd-containing medium and log 6.97 CFUg(-1) soil in As-containing medium. The composition of bacterial populations varied between locations. In Site 1, the classes Actinobacteria (36%) and Bacilli (24%) were well represented, while in Site 3 strains were mainly affiliated to classes Actinobacteria (35%), 'y-Proteobacteria (35%), and 13-Proteobacteria (12%). The order of metal(loid) toxicity for the isolated strains was Cd > As > Zn. Overall, 10 strains grew at 500 mg Cd L-1, 1000 mg Zn L-1, and 500 mg As L-1, being considered the most metal(loid)-tolerant bacteria. These strains belonged to genera Cupriavidus, Burkholderia, Novosphingobium, Sphingo bacterium, Castellaniella, Mesorhizobium, Chryseobacterium, and Rhodococcus and were mainly retrieved from Site 1. The multiple metal(loid)-tolerant strains isolated in this study have potential to be used in bioremediation/phytoremediation.