Elen Aquino Perpetuo

Engineering Bacteria for Bioremediation

Bioremediation is a process that uses microorganisms or their enzymes to promote degradation and/or removal of contaminants from the environment. The use of microbial metabolic ability for degradation/removal of environmental pollutants provides an economic and safe alternative compared to other physicochemical methodologies. However, although highly diverse and specialized microbial communities present in the environment do efficiently remove many pollutants, this process is usually quite slow, which leads to a tendency for pollutants to accumulate in the environment and this accumulation can potentially be hazardous. This is especially true for heavy metals. Heavy metal contamination is one of the most significant environmental issues, since metals are highly toxic to biota, as they decrease metabolic activity and diversity, and they affect the qualitative and quantitative structure of microbial communities. For treating heavy metal contaminated tailings and soils, bioremediation is still the most cost-effective method, although various heavy metals are beyond the bioaccumulation capabilities of microorganisms. Perhaps, because of the toxicity of these compounds, microorganisms have not evolved appropriate pathways to bioaccumulate them; populations of microorganisms responsible for this bioaccumulation are not large or active enough to remove these compounds completely, or complex mixtures of pollutants resist removal by existing pathways. The pathway used to accumulate these compounds is adsorption, where metals are taken up by microbial cells (biosorption). Biosorption mechanisms are numerous and are not yet fully understood. However, biosorption capacity often varies with test conditions, such as initial metal concentration, solution pH, contact time, biomass dosage, processing method, and so on. Accordingly, populations of microorganisms that are able to promote metal adsorption and accumulate them are not large or active enough to support these compounds by existing pathways. Furthermore, there are several strategies that optimize the bioremediation process of pollutants. One approach to enhance populations of microorganisms capable of pollutant removal is the addition of exogenous microorganisms in order to expand indigenous populations. This process, commonly known as bioaugmentation, can be performed either by adding microorganisms that naturally contain catabolic genes or those that have been genetically modified (GMOs). This strategy can also result in the transfer of plasmids containing the necessary genetic material between the different populations. Recent advances in the molecular biology field have been applied to microorganisms in order to produce novel strains with desirable properties for the

Phenol biodegradation by a microbial consortium: application of artificial neural network (ANN) modelling

In this study, an effective microbial consortium for the biodegradation of phenol was grown under different operational conditions, and the effects of phosphate concentration (1.4 g L−1, 2.8 g L−1, 4.2 g L−1), temperature (25 °C, 30 °C, 35 °C), agitation (150 rpm, 200 rpm, 250 rpm) and pH (6, 7, 8) on phenol degradation were investigated, whereupon an artificial neural network (ANN) model was developed in order to predict degradation. The learning, recall and generalization characteristics of neural networks were studied using data from the phenol degradation system. The efficiency of the model generated by the ANN was then tested and compared with the experimental results obtained. In both cases, the results corroborate the idea that aeration and temperature are crucial to increasing the efficiency of biodegradation.

Rapid bacteria identification from environmental mining samples using MALDI-TOF MS analysis.

Copper mining has polluted soils and water, causing a reduction of the microbial diversity and a change in the structure of the resident bacterial communities. In this work, selective isolation combined with MALDI-TOF MS and the 16S rDNA method were used for characterizing cultivable bacterial communities from copper mining samples. The results revealed that MALDI-TOF MS analysis can be considered a reliable and fast tool for identifying copper-resistant bacteria from environmental samples at the genera level. Even though some results were ambiguous, accuracy can be improved by enhancing reference databases. Therefore, mass spectra analysis provides a reliable method to facilitate monitoring of the microbiota from copper-polluted sites. The understanding of the microbial community diversity in copper-contaminated sites can be helpful to understand the impact of the metal on the microbiome and to design bioremediation processes.

Bioremediation potential of Pseudomonas aeruginosa and Enterobacter cloacae isolated from a copper-contaminated area

Background The Sossego mine, located in Canaa dos Carajas, Para, Brazil, has a pond of wastes with low copper concentrations economically unfeasable for extraction. In this place, we can improve environmental conditions and, at the same time, recover part of the ore diluted in these wastes, through evaluation and use of the local biodiversity, in bioremediation processes, once the use of this technology, will allow the decontamination as well the recovery of these metals with high value. Once there are some restrictions on the microorganisms introduction in the environment, it is important to establish the bioremediation potential of native species from a particular location. Therefore, it is necessary to study the biodegradation processes or biotransformation of compounds in the microbial biodiversity already adapted that are responsible for these processes in the environment, first in a bench scale[1]. In this work, among the 22 strains isolated from environmental samples from a copper mine, two of them presented great potential for bioremediation. Strains were identified and both were subjected to comparative study of their bioremediation potential and showed good results in concentrations up to 320ppm of copper.

Comparative study of microbial community from mining wastes - focus on future recovery of copper

Background The interaction between microorganisms and heavy metals has been occurring since the beginning of life on the planet, 4 billion years ago, which allowed the biological evolution of resistance in systems and the survival of these microorganisms in environments containing high metals concentrations of metals [1]. Recently, a bioremediation review presented by Perpetuo et.al. [2] considers the bioremediation technique as a feasible alternative for treatment and recovery of sites contaminated by heavy metals. However, a previous study of the microbial community living in these areas is necessary as well as the isolation of resistant and effective microorganisms with characteristics favorable to bioprocess, for remotion or concentration of these metals and also for subsequent metal reuse. This study investigates the bioprospection of natural selected copper-resistant organisms from a copper mining located in Pará, Brazil, for future reuse purposes.

Proteomic profiles comparison of three isolated bacteria strains from a copper processing area

Background Release of toxic metals is one of most significant environmental problems since industrial revolution, mainly because heavy metals are not degraded and, therefore, remain in the environment. Some natural ecosystems may contain high heavy metals concentrations and, thus, it is not surprising that genes resistance to heavy metals are easily found in bacteria living in these environmental samples [1]. Soils, sediments and waters contaminated with xenobiotics compounds are suitable substrates for isolation of these adapted microorganisms [2]. Thereby, proteome analysis has become a powerful tool for investigating global changes in prokaryotic gene expression. Once the two-dimensional electrophoresis (2-DE) displays all bacterial soluble proteins expressed at specific culture conditions on gel, high throughput screening of these induced proteins is possible. This study has a purpose to isolated bacteria that tolerate high concentrations of copper and compared their proteomic profiles. The understanding about the copper metabolic role of these microorganisms it will be helpful to improve bioprocesses of decontamination.

MALDI-Biotyper as a tool to identify polymer producer bacteria

The methylotrophs bacteria can use methane and methanol as carbon sources to produce biopolymers including the polyhydroxybutyrate (PHB) a very promised substitute for the environment contaminant oil-derived polypropylene. This kind of bacteria can be very effective to help to decrease PHB price production and promote its use in substitution of several environment contaminant plastics. The search for methylotroph bacteria able to produce PHB is a very arduous job being necessary to grow all isolates and submit all of them to extraction processes and product characterization. Looking for time reducing and optimization of resources, we tested the Matrix Assisted Laser Desorption/Ionization technique (MALDI-Biotyper) to identify polymer producer bacteria based on a single isolated colony with success. The results showed here will contribute to speed-up and increase the discoveries of new bacteria strains able to produce PHB and other biopolymers.

Microbial biodegradation of landfill leachates located in São Paulo state, Brazil

Background Leachate is one of the most problems present in landfills, mainly due to large production and the ability to cause serious environmental damages next to these areas. An activated sludge process is commonly used for biodegrading organic contaminants in wastewater using a mixed population of microorganisms. This technology is consolidated for wastewater treatment, and recently has been used as the first step in leachate treatment process. In this work, initially, physical-chemical and biological parameters of the leachate from different landfills (Areais and Bandeirantes, both in SP), were evaluated. Also the microbial consortium present in the sludge from a wastewater plant of the Capuava Petrobras Refinery, (SP) was characterized. Purpose of this work was to study the kinetic properties of the activated sludge process by removal of the pollutant organic matter, represented by the decrease of Total Organic Carbon (TOC). In order to verify the bioremediation efficiency, experiments were developed comparing the leachates before and after biological treatments. Results show that combination of leachate and sludge can decrease the organic load significantly, demonstrating bioremediation efficiency.