RESUMEN
The importance of short-chained aliphatic polyamines (PAs) to bacterioplankton-mediated carbon and nitrogen cycles has been repeatedly proposed. However, bacterial taxa and genes involved in the transformations of different PA compounds and their potential spatial variations remain unclear. This study collected surface bacterioplankton from nearshore, offshore, and open ocean stations in the Gulf of Mexico and examined how metatranscriptomes responded to additions of three single PA model compounds (i.e. putrescine, spermidine, or spermine). Our data showed an overrepresentation of genes affiliated with γ-glutamylation and spermidine cleavage pathways in metatranscriptomes received PA amendments and the expression level of each pathway varied among different PA compounds and sampling locations. PA-transforming taxa were affiliated with Actinobacteria, Bacteroidetes, Cyanobacteria, Planctomycetes, and Proteobacteria and their relative importance was also compound and location specific. These findings suggest that PAs are transformed via multiple pathways and by a diversity of marine bacterioplankton in the Gulf of Mexico. The relative importance of different PA transforming pathways and composition of functional microbial communities may be regulated by nutrient status of local environments.
Asunto(s)
Bacterias , Plancton , Poliaminas/metabolismo , Agua de Mar/microbiología , Actinobacteria/clasificación , Actinobacteria/genética , Actinobacteria/aislamiento & purificación , Bacterias/clasificación , Bacterias/genética , Bacterias/aislamiento & purificación , Bacteroidetes/clasificación , Bacteroidetes/genética , Bacteroidetes/aislamiento & purificación , Cianobacterias/clasificación , Cianobacterias/genética , Cianobacterias/aislamiento & purificación , Golfo de México , Metagenómica , Microbiota , Nitrógeno/metabolismo , Filogenia , Planctomycetales/clasificación , Planctomycetales/genética , Planctomycetales/aislamiento & purificación , Plancton/metabolismo , Plancton/microbiología , Proteobacteria/clasificación , Proteobacteria/genética , Proteobacteria/aislamiento & purificación , ARN Ribosómico 16S/genética , Agua de Mar/química , TranscriptomaRESUMEN
Xylanase and α-amylase enzymes participate in the degradation of organic matter, acting in hemicellulose and starch mineralization, respectively, and are in high demand for industrial use. Mangroves represent a promising source for bioprospecting enzymes due to their unique characteristics, such as fluctuations in oxic/anoxic conditions and salinity. In this context, the present work aimed to bioprospect xylanases from mangrove soil using cultivation-dependent and cultivation-independent methods. Through screening from a metagenomic library, three potentially xylanolytic clones were obtained and sequenced, and reads were assembled into contigs and annotated. The contig MgrBr135 was affiliated with the Planctomycetaceae family and was one of 30 ORFs selected for subcloning that demonstrated only amylase activity. Through the cultivation method, 38 bacterial isolates with xylanolytic activity were isolated. Isolate 11 showed an enzymatic index of 10.9 using the plate assay method. Isolate 39 achieved an enzyme activity of 0.43 U/mL using the colorimetric method with 3,5-dinitrosalicylic acid. Isolate 39 produced xylanase on culture medium with salinity ranging from 1.25 to 5%. Partial 16S rRNA gene sequencing identified isolates in the Bacillus and Paenibacillus genera. The results of this study highlight the importance of mangroves as an enzyme source and show that bacterial groups can be used for starch and hemicellulose degradation.
Asunto(s)
Bacterias/aislamiento & purificación , Endo-1,4-beta Xilanasas/genética , Microbiología del Suelo , Humedales , alfa-Amilasas/genética , Bacillus/genética , Bacillus/aislamiento & purificación , Bacillus/metabolismo , Bacterias/clasificación , Bacterias/genética , Bacterias/metabolismo , Proteínas Bacterianas/genética , Celulosa/metabolismo , Endo-1,4-beta Xilanasas/metabolismo , Genes Bacterianos/genética , Metagenómica , Paenibacillus/genética , Paenibacillus/aislamiento & purificación , Paenibacillus/metabolismo , Planctomycetales/clasificación , Planctomycetales/genética , Planctomycetales/aislamiento & purificación , Planctomycetales/metabolismo , ARN Ribosómico 16S , Almidón/metabolismo , alfa-Amilasas/metabolismoRESUMEN
The Cerrado biome in the Sete Cidades National Park, an Ecological Reserve in Northeastern Brazil, has conserved its native biodiversity and presents a variety of plants found in other savannas in Brazil. Despite this finding the soil microbial diversity and community structure are poorly understood. Therefore, we described soil bacterial diversity and distribution along a savanna vegetation gradient taking into account the prevailing environmental factors. The bacterial composition was retrieved by sequencing a fragment of the 16S ribosomal RNA gene. The bacterial operational taxonomic units (OTUs) were assigned to 37 different phyla, 96 classes, and 83 genera. At the phylum level, a core comprised by Proteobacteria, Acidobacteria, Actinobacteria, Firmicutes, Verrucomicrobia and Planctomycetes, was detected in all areas of Cerrado. 'Cerrado stricto sensu' and 'Cerradao' share more similarities between edaphic properties and vegetation and also present more similar bacterial communities, while 'Floresta decidual' and 'Campo graminoide' show the largest environmental differences and also more distinct bacterial communities. Proteobacteria (26%), Acidobacteria (21%) and Actinobacteria (21%) were the most abundant phyla within the four areas. All the samples present similar bacteria richness (alpha diversity) and the observed differences among them (beta diversity) were more related to the abundance of specific taxon OTUs compared to their presence or absence. Total organic C, N and P are the main abiotic factors structuring the bacterial communities. In summary, our findings show the bacterial community structure was clearly different across the Cerrado gradient, but that these environments share a bacterial phylum-core comprising Proteobacteria, Acidobacteria, Actinobacteria, Verrucomicrobia and Planctomycetes with other Brazilian savannas.