Oil spills in aquatic ecosystems cause irreparable damage to marine life and the coastal populations of affected areas. In recent years, chemical dispersants have been extensively used to remedy these impacted ecosystems, although these agents have been increasingly restricted due to their toxic potential. In this context, biosurfactants are emerging as a promising alternative to chemical dispersants, which have some advantages including low toxicity, high biodegradability and good ecological acceptability. Thus, this study aimed to the production of biosurfactant by the bacteria Serratia marcescens UCP 1549 for application as biodispersant. The experiment was carried out using wheat bran as substrate in solid-state fermentation (SSF) as low-cost technology. Biosurfactant production was verified by the reduction of surface tension (28.4 mN/m) and interfacial tension (4.1 mN/m) with n-hexadecane. Also, promising result of emulsification (94%) with burned motor oil was obtained. Acid precipitation yielded 52.0 g/kg dry substrate of biosurfactant, that was identified as an anionic compound of a lipopeptide nature by the Zeta potential and FTIR spectrum, respectively. The biomolecule showed stability under extreme conditions of temperature, pH and salinity, as well as low toxicity against the microcrustacean Artemia salina. In addition, the biosurfactant demonstrated excellent properties to dispersing burned motor oil in water (ODA = 50.24 cm²) and to washing of marine stones (100% removal of burned motor oil). Therefore, these results confirm SSF as a sustainable technology for the production of biodispersant by S. marcescens UCP 1549, promising in the bioremediation of marine ecosystems impacted by petroderivatives. GRAPHICAL ABSTRACT

Biosurfactants are amphipathic molecules with growing worldwide interest because of their low toxicity, high biodegradability and good ecological acceptability. They are produced by microorganisms and between them, filamentous fungi belonging Mucorales order have been reported as promising producers. However, most of these studies still use traditional submerged fermentation, a methodology with technical and economic problems. In this context, this work aimed the production of biosurfactant by Mucor hiemalis UCP 1309 using solid-state fermentation (SSF) as a low-cost alternative technology. Experiments were carried out using seven agro-industrial byproducts and wastes as substrates, supplemented with salt solution containing 5% waste soybean oil (WSO). Medium with the best result in the production of biosurfactant was used in a second fermentation, where a 22 full-factorial design (FFD) was performed to investigate the influence of inoculum size and concentration of WSO on surface tension. The results showed higher reduction of surface tension (to 28.1 mN/m) in fermentation using wheat bran. Also, the statistical analysis demonstrated significant effect of concentration of WSO on surface tension. Produced biosurfactant demonstrated excellent emulsifying properties with WSO, motor oil and burned motor oil, and the emulsions remained stable after 90 days of incubation. Therefore, this work demonstrated SSF as a suitable strategy for getting inexpensive and efficient biosurfactant and expediting its large-scale production. Moreover, we report, for the first time in the international literature, the production of biosurfactant using SSF by a Mucoralean fungus.

Microbial surfactants are amphiphilic molecules with attractive industrial prospects due to their advantages over commonly commercialized chemical surfactants, such as low toxicity, high biocompatibility and biodegradability, and efficiency at extreme conditions. However, the large-scale production of biosurfactants still becomes uncompetitive due to the low yields and onerous costs, being considered the use of renewable substrates as a viable strategy. In this sense, the present study aimed to investigate the sustainable production of biosurfactant by the yeast Issatchenkia orientalis UCP 1603 in 2 L of salt-based medium supplemented with 7.5% cassava wastewater, 5% corn steep liquor and 1% post-frying soybean oil. Fermentation was carried out in 2.8 L-Fernbach flasks for 72 h, at 28°C and 150 rpm, and reduction in surface tension to 30.1 mN/m was verified. The highest yield of the biosurfactant produced (4.02 g/L) was observed after extraction with 70% ethanol (2:1, v/v) and the isolated biosurfactant reduced the surface tension of the medium to 28.7 mN/m, the interfacial tension against n-hexadecane to 16.6 mN/m and has a CMC of 800 mg/L. The biocompound showed anionic and polymeric nature and did not present toxicity against cabbage (Brassica oleracea var. capitata) seeds. The stability in the range of pH 4-10, salinity 5-25% and temperature 5-100°C, evidenced a highly stable biosurfactant, with promising potential of application in several industrial activities or environmental processes in adverse conditions.

This study aimed to evaluate the bioleaching of copper from discarded printed circuit boards (PCBs) using the fungus Aspergillus tubingensis UCP 1208 as a sustainable and environmentally friendly alternative for the recovery of valuable metals. The methodology included the acclimatization of the fungus to different concentrations of crushed PCBs, followed by bioleaching assays and copper removal analysis through scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy (SEM-EDS) and inductively coupled plasma optical emission spectrometry (ICP-OES). SEM-EDS analyses revealed significant changes in the morphology and elemental composition of the PCBs after treatment, confirming the efficiency of copper solubilization. Quantitative results indicated that A. tubingensis, acclimatized with 1% (w/v) of crushed PCBs, removed 494.2 mg L⁻¹ of copper for a PCB load of 1 g L⁻¹, representing a 335.5% increase in removal compared to conventional acid digestion. These results demonstrate that bioleaching with A. tubingensis is a viable, efficient, and sustainable approach for the recovery of metals from electronic waste, offering a cleaner alternative to traditional chemical methods by avoiding the use of aggressive acids and contributing to circular economic practices.

The present study investigated the production of biosurfactant by Stenotrophomonas maltophilia UCP 1601under submerse fermentation using renewable substrates as carbon and nitrogen sources applying two statistical tools as Plakket-Burman experimental design and full factorial design to optimize the bioprocess. A partial characterization was performed by measuring the surface tension, emulsification index, determination of CMC, ionic charge. The biosurfactant was tested to different conditions of temperature, pH and salinity, in order to evaluate the stability of the biomolecule. The surface tension of the biosurfactant produced using corn steep liquor and glycerol was 27 mN/m, whose yield was 12.6 g/L, and its character is anionic. The critical micelle concentration (CMC) was 70% using the cell-free metabolic liquid. The biosurfactant was able to emulsify 56% of the burned engine oil. The biomolecule showed high functional stability and performance under extreme conditions of thermal, pH and saline concentrations stability. All determinations carried out confirm the generation of a stable, efficient bioproduct that contributes to the circular bioeconomy and the great potential for remediation under harsh environmental conditions.

This study evaluates the biotechnological potential of isolated microorganisms for the solubilization of critical and valuable metals in LED lamp waste through a biometallurgical process, called bioleaching or biomineration, which occurs with the production of metabolites by microorganisms capable of transforming metals from the solid phase to the liquid phase. Seven different bacteria from LED waste were isolated. Among them, six samples were identified as belonging to the Bacillus genus. The pH increase indicates that the solubilization of the metals occurred through cyanogenesis. Cellular viability was monitored throughout the process, with viable cells existing for up to 30 days of experiment. The Scanning Electron Microscopy images showed changes in the LED particles size after the bioleaching process, confirming the degradation of the material from the metabolites produced by the microorganism during the process.