2 research outputs found
Archaeal and bacterial communities of heavy metal contaminated acidic waters from zinc mine residues in sepetiba bay
9 p. : il., tab.Mining of metallic sulfide ore produces acidic
water with high metal concentrations that have harmful
consequences for aquatic life. To understand the composition
and structure of microbial communities in acid mine
drainage (AMD) waters associated with Zn mine tailings,
molecular diversity of 16S genes was examined using a
PCR, cloning, and sequencing approach. A total of 78
operational taxonomic units (OTUs) were obtained from
samples collected at five different sites in and around
mining residues in Sepetiba Bay, Brazil. We analyzed metal
concentration, physical, chemical, and microbiological
parameters related to prokaryotic diversity in low metal
impacted compared to highly polluted environments with
Zn at level of gram per liter and Cd–Pb at level of microgram
per liter. Application of molecular methods for
community structure analyses showed that Archaea and
Bacteria groups present a phylogenetic relationship with
uncultured environmental organisms. Phylogenetic analysis
revealed that bacteria present at the five sites fell into seven
known divisions, a-Proteobacteria (13.4%), b-Proteobacteria
(16.3%), c-Proteobacteria (4.3%), Sphingobacteriales
(4.3%), Actinobacteria (3.2%) Acidobacteria (2.1%),
Cyanobacteria (11.9%), and unclassified bacteria (44.5%).
Almost all archaeal clones were related to uncultivated
Crenarchaeota species, which were shared between high
impacted and low impacted waters. Rarefaction curves
showed that bacterial groups are more diverse than archaeal
groups while the overall prokaryotic biodiversity is lower in
high metal impacted environments than in less polluted
habitats. Knowledge of this microbial community structure
will help in understanding prokaryotic diversity, biogeography,
and the role of microorganisms in zinc smelting
AMD generation and perhaps it may be exploited for
environmental remediation procedures in this area
Complete genome sequence of the sugarcane nitrogen-fixing endophyte gluconacetobacter diazotrophicus PAL5
17 p. : il.Background: Gluconacetobacter diazotrophicus Pal5 is an endophytic diazotrophic bacterium that
lives in association with sugarcane plants. It has important biotechnological features such as
nitrogen fixation, plant growth promotion, sugar metabolism pathways, secretion of organic acids,
synthesis of auxin and the occurrence of bacteriocins.
Results: Gluconacetobacter diazotrophicus Pal5 is the third diazotrophic endophytic bacterium to be
completely sequenced. Its genome is composed of a 3.9 Mb chromosome and 2 plasmids of 16.6
and 38.8 kb, respectively. We annotated 3,938 coding sequences which reveal several
characteristics related to the endophytic lifestyle such as nitrogen fixation, plant growth
promotion, sugar metabolism, transport systems, synthesis of auxin and the occurrence of
bacteriocins. Genomic analysis identified a core component of 894 genes shared with
phylogenetically related bacteria. Gene clusters for gum-like polysaccharide biosynthesis, tad pilus,
quorum sensing, for modulation of plant growth by indole acetic acid and mechanisms involved in
tolerance to acidic conditions were identified and may be related to the sugarcane endophytic and
plant-growth promoting traits of G. diazotrophicus. An accessory component of at least 851 genes
distributed in genome islands was identified, and was most likely acquired by horizontal gene
transfer. This portion of the genome has likely contributed to adaptation to the plant habitat.
Conclusion: The genome data offer an important resource of information that can be used to
manipulate plant/bacterium interactions with the aim of improving sugarcane crop production and
other biotechnological applications