Enhanced production of surfactin using cassava wastewater and hydrophobic inducers: a prospection on new homologues.

Biosurfactants are amphipathic molecules that can be applied in a wide range of areas. The cost of production limits the industrial application of biosurfactants. Nevertheless, the biosurfactant productivity can be easily enhanced by inducers. This work aimed to investigate the effect of hydrophobic inducers on surfactin production by B. subtilis ATCC 6633 using cassava wastewater as low-cost culture medium. The submerged cultivation was carried out at 30 °C, 150 rpm for 72 h. The fermentation parameters used were bacterial growth, consumption of sugars, and surfactin production, including surfactin homologues. The surface tension decreased by 40% after 12 h, when compared to control. Depletion of sugars was observed in all experiments. Palmitic acid led to the highest yield in terms of surfactin production (≈ 1.3 g·L- 1 of pure surfactin). The inducers triggered the production of new surfactin homologues, that represent, potentially, new biological activities.

Fruits and vegetable-processing waste: a case study in two markets at Rio de Janeiro, RJ, Brazil.

Fruits and vegetables (FV) consumed in natura or processed produce a significant volume of waste, causing an economic deficit in the productive chain. FV markets feature a significant production of vegetable residues with potential of use, since they commercialize an increasing amount of minimally processed vegetables and fruit juices. To this end, it is important to identify, quantify, and characterize these wastes and to propose feasible and coherent alternatives for their use at regional and worldwide levels. In this paper, a case study of two FV markets in Rio de Janeiro, Brazil, was conducted to identify and quantify FV processing waste. Over a period of 20 days, the FV residues from 31 vegetables and 17 fruits were identified and weighed. It is estimated by extrapolation that 106,000 kg of FV were processed in 1 year in two units of FV markets and 48.6% of FV were discarded as by-products. This may be a consequence of factors that contribute to waste generation, such as the low preparation and/or training of the manipulators as well as the quality of the equipment and the maintenance thereof. Thus, studies that aim to understand the environmental impact by monitoring the of FV waste are fundamental, since this waste can be used as raw material and converted into value-added products.

Response mechanism of mine-isolated fungus Aspergillus niger IOC 4687 to copper stress determined by proteomics.

Proteomic analysis of the fungus Aspergillus niger showed that its capacity to absorb metals was boosted by physiological modification under metal stress conditions. To investigate the proteome elicited by copper stress, the mine-isolated strain A. niger IOC 4687 was cultured in the absence (control) or presence of copper ions (50 mg L-1) for 72 h. Protein extract from each treatment was analyzed by nano-liquid chromatography-mass spectrometry and proteins were identified using PEAKS Studio 8.5 software. Grouping proteins by functional category showed that antioxidant enzymes, such as catalase, superoxide dismutase, and cytochrome c peroxidase, were present in both treatments. However, heat shock proteins (Hsp60 and Hsp70) and some metalloproteins (LMBR1 domain protein and A. niger contig An09c0040) were only observed after copper treatment. These proteins were the cellular response to the stress conditions. In conclusion, significant changes in the proteome of A. niger were observed due to the presence of copper.

Evaluation of amicarbazone toxicity removal through degradation processes based on hydroxyl and sulfate radicals.

The herbicide amicarbazone (AMZ), which appeared as a possible alternative to atrazine, presents moderate environmental persistence and is unlikely to be removed by conventional water treatment techniques. Advanced oxidation processes (AOPs) driven by •OH and/or SO4•- radicals are then promising alternatives to AMZ-contaminated waters remediation, even though, in some cases, they can originate more toxic degradation products than the parent-compound. Therefore, assessing treated solutions toxicity prior to disposal is of extreme importance. In this study, the toxicity of AMZ solutions, before and after treatment with different •OH-driven and SO4•--driven AOPs, was evaluated for five different microorganisms: Vibrio fischeri, Chlorella vulgaris, Tetrahymena thermophila, Escherichia coli, and Bacillus subtilis. In general, the toxic response of AMZ was greatly affected by the addition of reactants, especially when persulfate (PS) and/or Fe(III)-carboxylate complexes were added. The modifications of this response after treatment were correlated with AMZ intermediates, which were identified by mass spectrometry. Thus, low molecular weight by-products, resulting from fast degradation kinetics, were associated with increased toxicity to bacteria and trophic effects to microalgae. These observations were compared with toxicological predictions given by a Structure-Activity Relationships software, which revealed to be fairly compatible with our empirical findings.