Biochar-immobilized Bacillus spp. for heavy metals bioremediation: A review on immobilization techniques, bioremediation mechanisms and effects on soil.

Heavy metals contamination present risks to ecosystems and human health. Bioremediation is a technology that has been applied to minimize the levels of heavy metals contamination. However, the efficiency of this process varies according to several biotic and abiotic aspects, especially in environments with high concentrations of heavy metals. Therefore, microorganisms immobilization in different materials, such as biochar, emerges as an alternative to alleviate the stress that heavy metals have on microorganisms and thus improve the bioremediation efficiency. In this context, this review aimed to compile recent advances in the use of biochar as a carrier of bacteria, specifically Bacillus spp., with subsequent application for the bioremediation of soil contaminated with heavy metals. We present three different techniques to immobilize Bacillus spp. on biochar. Bacillus strains are capable of reducing the toxicity and bioavailability of metals, while biochar is a material that serves as a shelter for microorganisms and also contributes to bioremediation through the adsorption of contaminants. Thus, there is a synergistic effect between Bacillus spp. and biochar for the heavy metals bioremediation. Biomineralization, biosorption, bioreduction, bioaccumulation and adsorption are the mechanisms involved in this process. The application of biochar-immobilized Bacillus strains results in beneficial effects on the contaminated soil, such as the reduction of toxicity and accumulation of metals in plants, favoring their growth, in addition to increasing microbial and enzymatic activity in soil. However, competition and reduction of microbial diversity and the toxic characteristics of biochar are reported as negative impacts of this strategy. More studies using this emerging technology are essential to improve its efficiency, to elucidate the mechanisms and to balance positive and negative impacts, especially at the field scale.

Rhodococcus: A promising genus of actinomycetes for the bioremediation of organic and inorganic contaminants.

Rhodococcus is a genus of actinomycetes that has been explored by the scientific community for different purposes, especially for bioremediation uses. However, the mechanisms governing Rhodococcus-mediated bioremediation processes are far from being fully elucidated. In this sense, this work aimed to compile the recent advances in the use of Rhodococcus for the bioremediation of organic and inorganic contaminants present in different environmental compartments. We reviewed the bioremediation capacity and mechanisms of Rhodococcus spp. in the treatment of polycyclic aromatic hydrocarbons, phenolic substances, emerging contaminants, heavy metals, and dyes given their human health risks and environmental concern. Different bioremediation techniques were discussed, including experimental conditions, treatment efficiencies, mechanisms, and degradation pathways. The use of Rhodococcus strains in the bioremediation of several compounds is a promising approach due to their features, primarily the presence of appropriate enzyme systems, which result in high decontamination efficiencies; but that vary according to experimental conditions. Besides, the genus Rhodococcus contains a small number of opportunistic species and pathogens, representing an advantage from the point of view of safety. Advances in analytical detection techniques and Molecular Biology have been collaborating to improve the understanding of the mechanisms and pathways involved in bioremediation processes. In the context of using Rhodococcus spp. as bioremediation agents, there is a need for more studies that 1) evaluate the role of these actinomycetes on a pilot and field scale; 2) use genetic engineering tools and consortia with other microorganisms to improve the bioremediation efficiency; and 3) isolate new Rhodococcus strains from environments with extreme and/or contaminated conditions aiming to explore their adaptive capabilities for bioremediation purposes.

Use of soil actinomycetes for pharmaceutical, food, agricultural, and environmental purposes.

In this article, we reviewed the international scientific production of the last years on actinomycetes isolated from soil aiming to report recent advances in using these microorganisms for different applications. The most promising genera, isolation conditions and procedures, pH, temperature, and NaCl tolerance of these bacteria were reported. Based on the content analysis of the articles, most studies have focused on the isolation and taxonomic description of new species of actinomycetes. Regarding the applications, the antimicrobial potential (antibacterial and antifungal) prevailed among the articles, followed by the production of enzymes (cellulases and chitinases, etc.), agricultural uses (plant growth promotion and phytopathogen control), bioremediation (organic and inorganic contaminants), among others. Furthermore, a wide range of growth capacity was verified, including temperatures from 4 to 60 °C (optimum: 28 °C), pH from 3 to 13 (optimum: 7), and NaCl tolerance up to 32% (optimum: 0-1%), which evidence a great tolerance for actinomycetes cultivation. Streptomyces was the genus with the highest incidence among the soil actinomycetes and the most exploited for different uses. Besides, the interest in isolating actinomycetes from soils in extreme environments (Antarctica and deserts, for example) is growing to explore the adaptive capacities of new strains and the secondary metabolites produced by these microorganisms for different industrial interests, especially for pharmaceutical, food, agricultural, and environmental purposes.

Fruit pomace as a promising source to obtain biocompounds with antibacterial activity.

The demand for natural compounds to replace synthetic additives has aroused the interest of different sectors of society, especially the scientific community, due to their safety, biocompatibility, biodegradability and low toxicity. Alternative sources for antimicrobial compounds have been explored, such as fruit pomace. These by-products have essential compounds in their composition with different potential for application in food and packaging. In this context, this review systematizes the use of pomace from different fruits as a source of antibacterial compounds. Also, it summarizes the extraction methods and the applications of these compounds. Grape pomace, cranberry, and apple extracts are the most explored for antibacterial control, especially against genus Listeria, Salmonella, Staphylococcus, and Escherichia. In addition, phenolic acids, anthocyanins, flavonoids, and proanthocyanins are the main compounds identified in the studied fruit pomace extracts. In the reviewed articles, the biocompounds recovery is performed by methods with the absence of high temperatures (>80 °C); in some studies, the solid-liquid extraction method at mild temperatures (<30 °C) was well explored, using ethanol and water as solvent. The use of fruit processing by-products for bacterial control highlights the possibility of favoring the three pillars of sustainability (social, economic, and environmental) in the food industry.

Current advances in microalgae-based bioremediation and other technologies for emerging contaminants treatment.

Emerging contaminants (EC) have been detected in effluents and drinking water in concentrations that can harm to a variety of organisms. Therefore, several technologies are developed to treat these compounds, either for their complete removal or degradation in less toxic by-products. Some technologies applied to the treatment of EC, such as adsorption, advanced oxidative processes, membrane separation processes, and bioremediation through microalgal metabolism, were identified by thematic maps. In this review, we used a bibliometric software from >1000 articles. These manuscripts, in general, present removals from 0% to 100% for different ECs. This efficiency varies between treatment technologies and the contaminants' physical-chemical properties and their concentration and operational parameters. This review explored the bioremediation of EC through microalgae with greater emphasis. The main mechanisms of action of microalgae in the bioremediation of ECs are biodegradation bioadsorption, and bioaccumulation. Also, physicochemical properties and removal efficiencies of >50 emerging contaminants are presented. Although there are challenges related to the generation of more toxic by-products and economic and environmental viability, these can be minimized with advances in the development of treatment technologies and even through the integration of different techniques to make the treatment of contaminants emerging from environmental media more sustainable.

Harvesting of Spirulina platensis using an eco-friendly fungal bioflocculant produced from agro-industrial by-products.

This study aimed to produce fungal biomass from agro-industrial by-products for later use as a bioflocculant in the Spirulina harvesting. The production of fungal biomass from Aspergillus niger was carried out in submerged fermentation, using media composed of wheat bran and/or potato peel. Fungal biomass was used as a bioflocculant in Spirulina cultures carried out in closed 5 L reactors and 180 L open raceway pond operated in batch and semi-continuous processes, respectively. Fungal biomass was able to harvest Spirulina platensis cultures with efficiencies between 90% and 100% after 2 h of sedimentation in some experimental conditions. Efficiencies higher than 80% were achieved in most tests without pH adjustment during bioflocculations, which shows that the developed method is a promising alternative to traditional Spirulina harvesting techniques. Above all, the development of an eco-friendly fungal-assisted bioflocculation process increases the sustainability of Spirulina biomass for different applications, especially biofuels.

Incidência de resíduos de serviços de saúde em cooperativas de triagem de materiais recicláveis / Incidence of healthcare waste in recycling materials cooperatives

RESUMO Os resíduos de serviços de saúde (RSS) são todos aqueles resíduos gerados nos serviços que prestam atendimento à saúde humana ou animal. Os RSS são classificados em cinco grupos (Grupo A, Grupo B, Grupo C, Grupo D e Grupo E), dos quais uma parcela apresenta periculosidade. A legislação brasileira recomenda que os resíduos pertencentes ao Grupo D sejam reciclados. Contudo, com base na má segregação existente, o encaminhamento desses materiais representa riscos aos profissionais que manejam os resíduos intra e extraestabelecimentos de saúde, incluindo os trabalhadores que atuam junto às cooperativas de triagem de materiais recicláveis. Nesse contexto, este trabalho teve como objetivo verificar a presença de RSS destinados inadequadamente às cooperativas de triagem de materiais recicláveis de um município da zona Sul do Rio Grande do Sul. Para tanto, foi realizada uma caracterização quali-quantitativa dos RSS incidentes nas cinco cooperativas do município durante o período de quatro semanas. A partir dos resultados obtidos, verificou-se a presença de RSS no programa de coleta seletiva (PCS) municipal e, também, que a quantidade incidente varia conforme a cooperativa estudada e a semana avaliada. Ao final das caracterizações, foram quantificados 36,23 kg de RSS entre todas as cooperativas. Tais resultados indicam falhas na segregação e na destinação de RSS, seja pela população e/ou pelos estabelecimentos de saúde, além de evidenciarem a fragilidade existente no PCS do município. À vista disso, torna-se necessária a implementação de políticas públicas, tanto educativas quanto de fiscalização, que sejam capazes de assegurar maior segurança no âmbito de trabalho das cooperativas de triagem de materiais recicláveis.

ABSTRACT Healthcare waste (HCW) is all the waste generated by human or animal health care activities. HCW is classified into five groups, of which a portion presents hazardousness. Brazilian legislation recommends that waste belonging to Group D be recycled. However, based on the poor existing waste segregation, the forwarding of these materials presents risks to the professionals who handle them inside and out of health care facilities, including the workers within recyclable material waste picker cooperatives. In such a context, this study aimed to investigate the presence of HCW inappropriately sent to waste pickers cooperatives of a municipality in the south of Rio Grande do Sul. To this end, a qualitative and quantitative characterization of HCW incidence in the five cooperatives of the municipality was performed during the period of four weeks. From the results obtained, it was possible to verify the presence of HCW in the municipal selective waste collection program and that HCW quantities vary according to the waste pickers cooperative studied and the week being evaluated. At the end of the characterizations, 36.23 kg of HCW were quantified amongst all the cooperatives. Such results indicate flaws in HCW segregation and destination, either by the population and/or by health care facilities, in addition to showing the fragility in the municipality's selective waste collection program. In view of this, it is necessary to implement public policies, both educational and supervisory, that can ensure greater safety in the work environment of recyclable material waste picker cooperatives.