Marcos Rogério Tótola

Photochemical responses and oxidative stress in two clones of Coffea canephora under water deficit conditions

Abstract The effects of water deficit on photochemical parameters and activities of superoxide dismutase (SOD), catalase (CAT) and ascorbate peroxidase (APX), as well as, cellular damages were investigated in two clones of Coffea canephora differing in drought tolerance. After 6 days without irrigation, predawn leaf water potential fell to −3.0 MPa that was accompanied by the suppression of net photosynthesis in both clones. The variable to maximum chlorophyll fluorescence ratio remained unchanged regardless of the imposed treatments. Both clones showed a similar decline (about 25%) in the photochemical quenching coefficient, but only the drought-sensitive clone exhibited an enhancement (31%) of thermal deactivation under water deficit conditions. The quantum yield of electron transport decreased similarly in both genotypes. Under drought conditions, activities of SOD, CAT and APX increased to a greater extent in the drought-tolerant clone than in the drought-sensitive one. This seemed to be matched with higher protection against oxidative stress, as judged from the lower levels of lipid peroxidation and electrolyte leakage in the drought-tolerant clone. Thus, the ability to increase the antioxidant system activity in order to limit cellular damages might be an important attribute linked to the drought tolerance in C. canephora.

Data analysis for 16S microbial profiling from different benchtop sequencing platforms

Progress in microbial ecology is confounded by problems when evaluating results from different sequencing methodologies. Contrary to existing expectations, here we demonstrate that the same biological conclusion is reached using different NGS technologies when stringent sequence quality filtering and accurate clustering algorithms are applied.

Characterizing the microbiota across the gastrointestinal tract of a Brazilian Nelore steer.

The gastrointestinal tracts (GIT) of herbivores harbor dense and diverse microbiota that has beneficial interactions with the host, particularly for agriculturally relevant animals like ruminants such as cattle. When assessing ruminant health, microbiological indicators are often derived from the rumen or feces. However, it is probable that ruminal and fecal microbiota do not reflect the microbial communities within the GIT of ruminants. To test this, we investigated the compartments of the GIT from a Brazilian Nelore steer and performed a 16S rRNA pyrosequencing analysis on the collected samples. Our results showed high intra-individual variation, with samples clustering according to their location in the GIT including the forestomach, small intestine, and large intestine. Although sequences related to the phyla Firmicutes and Bacteroidetes predominated all samples, there was a remarkable variation at the family level. Comparisons between the microbiota in the rumen, feces, and other GIT components showed distinct differences in microbial community. This work is the first intensive non-culture based GIT microbiota analysis for any ruminant and provides a framework for understanding how host microbiota impact the health of bovines.

Evaluation of bacterial surfactant toxicity towards petroleum degrading microorganisms

The acute toxicity of bacterial surfactants LBBMA111A, LBBMA155, LBBMA168, LBBMA191 and LBBMA201 and the synthetic surfactant sodium dodecyl sulfate (SDS) on the bioluminescent bacterium Vibrio fischeri was evaluated by measuring the reduction of light emission (EC(20)) by this microorganism when exposed to different surfactant concentrations. Moreover, the toxic effects of different concentrations of biological and synthetic surfactants on the growth of pure cultures of isolates Acinetobacter baumannii LBBMA04, Acinetobacter junni LBBMA36, Pseudomonas sp. LBBMA101B and Acinetobacter baumanni LBBMAES11 were evaluated in mineral medium supplemented with glucose. The EC(20) values obtained confirmed that the biosurfactants have a significantly lower toxicity to V. fischeri than the SDS. After 30 min of exposure, bacterial luminescence was almost completely inhibited by SDS at a concentration of 4710 mg L(-1). Growth reduction of pure bacterial cultures caused by the addition of biosurfactants to the growth medium was lower than that caused by SDS.

Biodegradability of bacterial surfactants.

This work aimed at evaluating the biodegradability of different bacterial surfactants in liquid medium and in soil microcosms. The biodegradability of biosurfactants by pure and mixed bacterial cultures was evaluated through CO2 evolution. Three bacterial strains, Acinetobacter baumanni LBBMA ES11, Acinetobacter haemolyticus LBBMA 53 and Pseudomonas sp. LBBMA 101B, used the biosurfactants produced by Bacillus sp. LBBMA 111A (mixed lipopeptide), Bacillus subtilis LBBMA 155 (lipopeptide), Flavobacterium sp. LBBMA 168 (mixture of flavolipids), Dietzia Maris LBBMA 191(glycolipid) and Arthrobacter oxydans LBBMA 201(lipopeptide) as carbon sources in minimal medium. The synthetic surfactant sodium dodecyl sulfate (SDS) was also mineralized by these microorganisms, but at a lower rate. CO2 emitted by a mixed bacterial culture in soil microcosms with biosurfactants was higher than in the microcosm containing SDS. Biosurfactant mineralization in soil was confirmed by the increase in surface tension of the soil aqueous extracts after incubation with the mixed bacterial culture. It can be concluded that, in terms of biodegradability and environmental security, these compounds are more suitable for applications in remediation technologies in comparison to synthetic surfactants. However, more information is needed on structure of biosurfactants, their interaction with soil and contaminants and scale up and cost for biosurfactant production.

Brazilian Microbiome Project: revealing the unexplored microbial diversity--challenges and prospects.

The Brazilian Microbiome Project (BMP) aims to assemble a Brazilian Metagenomic Consortium/Database. At present, many metagenomic projects underway in Brazil are widely known. Our goal in this initiative is to co-ordinate and standardize these together with new projects to come. It is estimated that Brazil hosts approximately 20 % of the entire world’s macroorganism biological diversity. It is 1 of the 17 countries that share nearly 70 % of the world’s catalogued animal and plant species, and is recognized as one of the most megadiverse countries. At the end of 2012, Brazil has joined GBIF (Global Biodiversity Information Facility), as associated member, to improve the access to the Brazilian biodiversity data in a free and open way. This was an important step toward increasing international collaboration and clearly shows the commitment of the Brazilian government in directing national policies toward sustainable development. Despite its importance, the Brazilian microbial diversity is still considered to be largely unknown, and it is clear that to maintain ecosystem dynamics and to sustainably manage land use, it is crucial to understand the biological and functional diversity of the system. This is the first attempt to collect and collate information about Brazilian microbial genetic and functional diversity in a systematic and holistic manner. The success of the BMP depends on a massive collaborative effort of both the Brazilian and international scientific communities, and therefore, we invite all colleagues to participate in this project.

Inferências sobre atividade rizosférica de espécies com potencial para fitorremediação do herbicida tebuthiuron

SUMMARY : RHIZOSPHERIC ACTIVITY OF POTENTIALLY PHYTOREME-DIATIVE SPECIES FOR TEBUTHIURON-CONTAMINATEDSOIL The rhizospheric microbial action, accelerating the degradation of compounds in thesoil, is known as phytostimulation. It represents one of the main phytoremediationmechanisms in herbicide-contaminated soil. Tebuthiuron-tolerant plants, which are ableto stimulate their rhizospheric microorganisms, could be highly interesting for thephytoremediation of this herbicide. This study aimed at evaluating the rhizospheric activityof four plant species with phytoremediation potential for tebuthiuron and to infer on thecontribution of the roots to the process of decontamination of this herbicide. The rhizosphericsoil of jackbean ( Canavalia ensiformis ), pearl millet ( Pennisetum glaucum ), Georgia velvetbean (S tizolobium deeringianum ), and black velvet bean ( Stizolobium aterrimum ), plus acontrol treatment (without plant) were analyzed without and with tebuthiuron at 0.73 ig g -1 .The CO

Oil Recovery from Fuel Oil Storage Tank Sludge Using Biosurfactants

The petroleum industry generates large amounts of solid and semisolid wastes known as oily sludges. The composition of oily sludge varies due to the large diversity in the quality of crude oils, differences in the processes used for oil-water separation, leakages during industrial processes, and also mixing with the existing oily sludge. Usually, the oily sludge contains water, sand, oils, grease, organic compounds, chemical elements, and metals. Those sludges can be generated in several steps of the petroleum production and refining, such as in oil/water separation steps and in the bottom of tanks. The accumulation of oily residues in petroleum industry poses a serious environmental problem. The purpose of this work was evaluate an alternative process to removal of oily sludges through the use of biosurfactants to reduce the viscosity and promote formation of oil/water emulsions making sludge pumping easier and permitting crude oil recovery after breaking the emulsion. Five bacterial isolates were selected for their biosurfactant production potential after screening microorganisms recovered from oil-contaminated sites. Supernatants obtained from autoclave cell suspensions (hereby referred to as autoclaved-supernatant) were mixed with oily sludge collected from fuel oil storage tanks to a final concentration of 0.01%, in order to separate the oil from the inert material. The process proved to be highly efficient for oil recovery, and resulted in up to 95% reduction in sludge volume. The use of cell-free supernatant medium obtained from biosurfactant-producing bacterial strains to treat oily sludges may be an economically and environmentally viable technology, considering the small volume of microbial culture required for the treatment.

Prospect, isolation, and characterization of microorganisms for potential use in cases of oil bioremediation along the coast of Trindade Island, Brazil

In the present study, acrylic coupons with a thin layer of oil on the surface were incubated in the coastal water of Trindade Island, Brazil, for 60 days. The microorganisms adhered to the coupons were isolated using enrichment medium with hexadecane and naphthalene as the sole carbon and energy source. A total of 15 bacterial isolates were obtained, and the ability of these isolates to use different hydrocarbons as the source of carbon and energy was investigated. None of the isolates produced biosurfactants under our experimental conditions. Subsequently, identification methods such as partial sequencing of the 16S rRNA gene and analysis of fatty acids (MIDI) profile were employed. Among the 15 isolates, representatives of Actinobacteria, Firmicutes, and Alphaproteobacteria were detected. The isolates Rhodococcus rhodochrous TRN7 and Nocardia farcinica TRH1 were able to use all the hydrocarbons added to the culture medium (toluene, octane, xylene, naphthalene, phenanthrene, pyrene, hexadecane, anthracene, eicosane, tetracosane, triacontane, and pentacontane). Polymerase chain reaction amplification of the DNA isolated by employing primers for catechol 2,3-dioxygenase, alkane dehydrogenase and the alpha subunit of hydroxylating dioxygenases polycyclic aromatic hydrocarbon rings genes demonstrated that various isolates capable of utilizing hydrocarbons do not exhibit genes of known routes of catabolism, suggesting the existence of unknown catabolic pathways in these microorganisms. Our findings suggest that the microbiota associated to the coast of tropical oceanic islands has the ability to assist in environmental regeneration in cases of accidents involving oil spills in its shore. Thus, it motivates studies to map bioremediation strategies using the autochthonous microbiota from these environments.

Mobilisation of bacteria in a fine-grained residual soil by electrophoresis.

An investigation of electrokinetic bacterial mobilisation in a residual soil from gneiss is presented here. The experimental program aimed at assessing the efficacy of electrophoresis against the electro-osmotic flow to transport endospores of Bacillus subtilis LBBMA 155 and nitrogen-starved cells of Pseudomonas sp. LBBMA 81. Electrokinesis was performed on a low hydraulic reconstituted clayey soil column submitted to a 5mA electrical current for 24h. Cells were coccoid-shaped and characterised as possessing low surface hydrophobicity and less than 1microm in diameter. Distribution coefficient for B. subtilis in the soil was between 16.8 and 19.9 times higher than that for Pseudomonas sp. Distribution coefficient for B. subtilis between eluate and anionic exchange column was 11.8 times higher than that for Pseudomonas sp. After the electrokinesis, it was shown that cells and endospores were distributed hyperbolically through the soil probe and moved against the electro-osmotic flow; however, endospores were transported throughout all soil core and starved cells only till half of its length. The higher transport efficiency of B. subtilis endospores was attributed to their higher negative charge on cell surface. These results demonstrate that electrokinesis can be used for bacteria transport in soils with low hydraulic conductivity, even against the electro-osmotic flow.