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BACKGROUND: As global awareness regarding climate change and environmental pollution outcomes arise, eco-friendly and negative emission technologies emerge. METHODS: In this scenario, polyhydroxyalkanoate (PHA)-accumulating microorganisms play an important role in the transition from the petrochemical-based non-biodegradable polymer to renewable, eco-friendly, and biocompatible materials. More specifically, CO2 can be converted to biopolymers through photosynthesis by cyanobacteria and algae, posing as a promising technology for renewable material, CO2, and petroleum-dependence mitigations. However, although many microorganisms can accumulate PHA intracellularly, limitations persist, such as the elevated cost and limited market availability. RESULTS: Herein is presented a patent-based mapping on technological trends of PHAs production, including its production by microalgae and cyanobacteria using the Questel Orbit Intelligence software (version 1.9.8) in complement with the Espacenet Patent Search database. CONCLUSION: The inquiry on PHAs retrieved 34,243 patents filed since 1912, whereas 156 are related to their specific production by photosynthetic microorganisms, evidencing a prospective market for intellectual property.

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The chemical synthesis of monoatomic metallic copper is unfavorable and requires inert or reductive conditions and the use of toxic reagents. Here, we report the environmental extraction and conversion of CuSO4 ions into single-atom zero-valent copper (Cu0) by a copper-resistant bacterium isolated from a copper mine in Brazil. Furthermore, the biosynthetic mechanism of Cu0 production is proposed via proteomics analysis. This microbial conversion is carried out naturally under aerobic conditions eliminating toxic solvents. One of the most advanced commercially available transmission electron microscopy systems on the market (NeoArm) was used to demonstrate the abundant intracellular synthesis of single-atom zero-valent copper by this bacterium. This finding shows that microbes in acid mine drainages can naturally extract metal ions, such as copper, and transform them into a valuable commodity.

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Large-scale cultivations of photoautotrophic microorganisms represent a very promising and potentially cost-effective alternative for climate change mitigation, when associated to the co-production of high value bioproducts, such as fatty acids and carotenoids, considering the growing demand for natural products. During microalgae cultivation, CO2 enrichment is a requirement to reach high productivities, although high CO2 levels are normally stressful to microalgae. On the other hand, cellular stress is a well reported strategy to induce carotenoid and fatty acids production. This work evaluated extracellular carotenoid production from the mangrove-isolated microalga Parachlorella kessleri cultivated under 5, 15 and 30% CO2 in stirred tank photobioreactors. In the 10th day of cultivation, CO2 supply was interrupted until the end of the cultivation (14th day), causing a stressful and imperative condition for microalgae cells to release the red pigment. Growth kinetics, physiological parameters and bioproducts production were evaluated. Growth kinetics were similar under all tested conditions and differences were not statistically significant, with the highest values of µmax, biomass concentration, lipid content and CO2 fixation rate of 0.77 d-1, 1.24 g L-1, 241 mg g-1 (dw) and 165 mg L-1 d-1, respectively. In contrast, total carotenoid concentrations varied significantly (p < 0.01), with the highest concentration of 0.030 µg mL-1 under 5% CO2. The produced red pigment presented antioxidant activity and characteristics of carotenoids confirmed by UV-vis and tandem mass spectrometry (MS/MS). The fatty acid profiles in the biomass varied in response to CO2 levels in the cultivations. In general, higher CO2 concentrations (15 and 30%) favored the production of saturated and mono-unsaturated fatty acids, suitable as biodiesel feedstock, while drastically decreased the production of the polyunsaturated.

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Phthalates are widely used as plasticizers in many industrial products due to their chemical properties that confer flexibility and durability to building materials, lubricants, solvents, insect repellents, clothing, cosmetics, being widely distributed in the environment. Besides persistent, they are also considered endocrine-disrupting compounds (EDCs), causing a global concern about their release into the environment, once they can alter the reproductive and endocrine health of humans systems. Under natural conditions, photodegradation and hydrolysis rates of phthalates are often very slow; therefore, microbial degradation is a natural way to treat these pollutants. In this context, three bacterial consortia (CMS, GMS and GMSS) were isolated from environmental samples from the Santos Estuarine System (SES) and were able to grow on diethyl-phthalate (DEP) as an only carbon source. From the GMSS consortium, three different strains were isolated and identified as Burkholderia cepacia, Pseudomonas koreensis and Ralstonia pickettii by molecular and mass spectrometry (MALDI-TOF-Biotyper) techniques. Considering there are no reports about Ralstonia genus on phthalates degradation, this strain was chosen to proceed the kinetics experiments. Ralstonia pickettii revealed a great ability to degrade DEP (300 mg/L) in less than 24 h. This is the first report implicating R. pickettii in DEP degradation.

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An alternative for non-biodegradable oil-based plastics has been the focus of many researchers throughout the years. Polyhydroxyalkanoates (PHAs) are potential substitutes due to their biodegradable characteristic and diversity of monomers that allow different biopolymer compositions and physical-chemical properties suitable for a variety of applications. The most well-known biopolymer from this class, poly(3-hydroxybutyrate) (P3HB), is already produced industrially, but its final price cannot compete with the oil-based plastics. As a low-volume high-value bioproduct, P3HB must be produced through a cheap and abundant feedstock, with high productivity and a feasible purity process in order to become an economically attractive bioproduct. In this scenario, we report a methylotrophic strain isolated from an estuarine contaminated site identified as Methylorubrum sp. highly tolerant to methanol and with great accumulation capacity of 60% (CDW) in 48 h through a simple strategy of batch fermentation with discontinuous methanol addition that could help lower P3HB's processing costs and final price.

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The human exposure to bisphenol A (BPA) occurs frequently. Once, this compound was one of the highest volume chemicals produced worldwide and used as a plasticizer in many products. However, even at low concentration, it can cause severe damage to the endocrine system because of its endocrine disruptor activity. Thus, mitigation studies to remove or reduce this contaminant from the environment are essential. An alternative method of removing it from the environment is the use of bioremediation processes to the selected bacteria isolated from a BPA-impacted area. In this work, four halotolerant strains were isolated from the Santos Estuary System, one of the most important Brazilian examples of environmental degradation. In the present work, one strain presented strong BPA tolerance and high BPA-degrading activity and could grow in a minimum medium containing BPA as the main carbon source. Strain MH137742 was identified as Shewanella haliotis, based on 16S rRNA gene sequencing and mass spectrometry identification by MALDI-TOF Biotyper. Shewanella haliotis was able to tolerate up to 150 mg L-1 of BPA and biotransform 75 mg L-1 in 10 h in a liquid culture medium. Based on the analysis of the produced metabolites by LC-MS, it was possible to predict the metabolic pathway used by this microorganism to degrade the BPA.

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Metal contamination exerts environmental pressure on several lifeforms. Since metals are non-biodegradable and recalcitrant, they accumulate in living beings and spread through the food chain. Thus, many life forms are affected by environmental metal contamination, such as plants and microorganisms. In the case of microorganisms, scarce information is available on how metals affect them. As a highly resistant form of life, microorganisms can adapt to several environmental pressures through genetic modifications, changing their metabolism to overcome new conditions, and continuing to thrive in the same place. In this study, an Acinetobacter sp. strain was isolated from a copper mine, which presented very high resistance to copper, growing in copper concentrations of up to 7 mM. As a result of its metabolic response in the presence of 3 mM of copper, the expression of 35 proteins in total was altered. The proteins were identified to be associated with the glycolytic pathway, membrane transport, biosynthesis and two proteins directly involved in copper homeostasis (CopA and CopB).

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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.

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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 degrees C, 30 degrees C, 35 degrees 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 ofbiodegradation.

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