ena-STUDY-EESC/USP-02-04-2019-18:24:11:117-6
Taxonomic Diversity and Lignin Biodegradation in Bacterial Community of Caatinga Soil
The Caatinga is an exclusively brazilian biome, accounting for approximately 11% of the national territory and considered the most diverse semi-arid region of the world.On the other hand, it is the least protected biome conservation units in Brazil, and the leastscientifically explored among all other biomes of the country, with 41% of its territory eversampled. The semi-arid climate, low water availability and extremely variable rainfall attachgreat variability of adaptive mechanisms to the native biota of Caatinga, resulting fromresponses to extreme environmental conditions that characterize their regions. Soils representa major natural reservoir of genetical and biochemical diversity, as well as a variety of niches.However, the knowledge about the microbial diversity present in the soil of Caatinga and thebiotechnological potential associated with it is still incipient and scarce. Currently, millions oftons of lignin and related compounds are produced as waste from effluents of paper andcellulose pulp industries, with the forecast which this number will increase in the near future,given the recent development of alternative fuels generated from lignocellulosic biomass. Inparticular, microbial enzymes from the group of ligninases, which catalyze the bioconversionand biodegradation of lignin, have received much attention of scientists in recent decades.Among these enzymes, laccases has been highlighted by its phenolic oxidation of lignin,being exploited both industrially (paper and pulp mills, textile and biofuels industries) andenvironmentally (like detoxification of recalcitrant aromatic compounds and remediation ofcontaminated soils and rivers). In this sense, this work investigated native bacterialcommunities from soil of Caatinga under the influence of the addition of lignin, applying apolyphasic approach to the analysis of taxonomic diversity. At the same time, bacteria withligninolytic potential were isolated and cultivated for molecular and functional assays toscreening bacterial genes from laccases, hoping a future application in the treatment ofsewage and contaminated soils. During 27 days of sampling, 156 bacteria potentiallyligninolytic were isolated (39 derived directly from microcosms supplemented with 10%lignin), all of them grown in culture medium with 0.3% lignin (w/v). The data generated byIllumina sequencing of 16S rRNA gene showed that the introduction of lignin in themicrocosms provided changes in the abundance of taxa belonging to the bacterial communityover time, affecting the microbiota composition in the evaluated microcosms. While the mostbacterial taxonomic groups have been supressed, some genera such as Bacillus andStreptomyces showed significant increase in abundance under enrichment, as well as othergroups not described yet in the literature.
The Caatinga is an exclusively brazilian biome, accounting for approximately 11% of the national territory and considered the most diverse semi-arid region of the world.On the other hand, it is the least protected biome conservation units in Brazil, and the leastscientifically explored among all other biomes of the country, with 41% of its territory eversampled. The semi-arid climate, low water availability and extremely variable rainfall attachgreat variability of adaptive mechanisms to the native biota of Caatinga, resulting fromresponses to extreme environmental conditions that characterize their regions. Soils representa major natural reservoir of genetical and biochemical diversity, as well as a variety of niches.However, the knowledge about the microbial diversity present in the soil of Caatinga and thebiotechnological potential associated with it is still incipient and scarce. Currently, millions oftons of lignin and related compounds are produced as waste from effluents of paper andcellulose pulp industries, with the forecast which this number will increase in the near future,given the recent development of alternative fuels generated from lignocellulosic biomass. Inparticular, microbial enzymes from the group of ligninases, which catalyze the bioconversionand biodegradation of lignin, have received much attention of scientists in recent decades.Among these enzymes, laccases has been highlighted by its phenolic oxidation of lignin,being exploited both industrially (paper and pulp mills, textile and biofuels industries) andenvironmentally (like detoxification of recalcitrant aromatic compounds and remediation ofcontaminated soils and rivers). In this sense, this work investigated native bacterialcommunities from soil of Caatinga under the influence of the addition of lignin, applying apolyphasic approach to the analysis of taxonomic diversity. At the same time, bacteria withligninolytic potential were isolated and cultivated for molecular and functional assays toscreening bacterial genes from laccases, hoping a future application in the treatment ofsewage and contaminated soils. During 27 days of sampling, 156 bacteria potentiallyligninolytic were isolated (39 derived directly from microcosms supplemented with 10%lignin), all of them grown in culture medium with 0.3% lignin (w/v). The data generated byIllumina sequencing of 16S rRNA gene showed that the introduction of lignin in themicrocosms provided changes in the abundance of taxa belonging to the bacterial communityover time, affecting the microbiota composition in the evaluated microcosms. While the mostbacterial taxonomic groups have been supressed, some genera such as Bacillus andStreptomyces showed significant increase in abundance under enrichment, as well as othergroups not described yet in the literature.