Adsorption in Jar-Test system: a study of the physico-chemical interactions of the chitosan biopolymer with the textile dye DO 2GL

The incorrect disposal of contaminated effluents from textile industries is a major contribution to their environmental impact. We aimed to use the chitosan biopolymer from industrial sources as a potential adsorbent agent. The experiments were performed in Jar-Test simulating an industrial scale treatment. Both pH and mass variations were analyzed. Our UV spectra results showed that all datasets fitted to the Langmuir model, indicating the formation of monolayers. Kinetics studies confirmed that adsorption follows a pseudo-second order model, in addition to a chemisorption pattern during adsorption. Kinetics studies also demonstrated intraparticle diffusion, which confirmed a strong adsorbate/adsorbent interaction with the dye. The Jar-Test proved to be an efficient system to simulate treatment of effluents on an industrial scale, thus ranking chitosan powder as a good adsorbent and eligible to future large-scale applications.Keywords: chitosan, intraparticle diffusions, chemisorption, isotherms, kinetics

A simplified curcumin targets the membrane of Bacillus subtilis

Abstract Curcumin is the main constituent of turmeric, a seasoning popularized around the world with Indian cuisine. Among the benefits attributed to curcumin are anti‐inflammatory, antimicrobial, antitumoral, and chemopreventive effects. Besides, curcumin inhibits the growth of the gram‐positive bacterium Bacillus subtilis. The anti‐B. subtilis action happens by interference with the division protein FtsZ, an ancestral tubulin widespread in Bacteria. FtsZ forms protofilaments in a GTP‐dependent manner, with the concomitant recruitment of essential factors to operate cell division. By stimulating the GTPase activity of FtsZ, curcumin destabilizes its function. Recently, curcumin was shown to promote membrane permeabilization in B. subtilis. Here, we used molecular simplification to dissect the functionalities of curcumin. A simplified form, in which a monocarbonyl group substituted the β‐diketone moiety, showed antibacterial action against gram‐positive and gram‐negative bacteria of clinical interest. The simplified curcumin also disrupted the divisional septum of B. subtilis; however, subsequent biochemical analysis did not support a direct action on FtsZ. Our results suggest that the simplified curcumin exerted its function mainly through membrane permeabilization, with disruption of the membrane potential necessary for FtsZ intra‐cellular localization. Finally, we show here experimental evidence for the requirement of the β‐diketone group of curcumin for its interaction with FtsZ

Oregano essential oil and its main components Thymol and Carvacrol as alternatives to control citrus canker

Plant Essential Oils and their constituents are well-known for their properties as antimicrobial agents and are labeled as Generally Recognized as Safe (GRAS), prompting studies around their usage in the control of food-borne microorganisms and phytopathogens. In this study, we evaluated Oregano Essential Oil (OEO), Thymol (THY) and Carvacrol (CAR) for the control of Xanthomonas citri subsp. citri (X. citri). In vitro antibacterial assays revealed that CAR and THY inhibit X. citri growth at the concentrations of 100 µg.mL-1 and 114 µg.mL-1, lower than OEO (136 µg.mL-1). Bactericidal effects were observed at 400 µg.mL-1 for OEO and 200 ug.mL-1 for CAR and THY. Investigating potential cellular targets for the compounds showed that after 30 minutes of exposure up to 84% of the cells had their membranes disrupted, implicating the membrane as the primary target. Phytotoxicity evaluations using Lactuca sativa and Solanum lycopersicum seeds showed an acute toxic effect in all treatments above 200 µg.mL-1, except for OEO and THY in S. lycopersicum at lower concentrations. Regarding their protective effect on citrus leaves, CAR showed no effect when compared to the untreated control (0.39 and 0.50 lesions per cm2, respectively). OEO and THY were able to reduce significantly citrus canker symptoms (0.18 and 0.11 lesions per cm2, respectively). In addition, no toxic effects were observed on citrus leaves in all treatments. THY inhibits X. citri growth and the development of citrus canker lesions. These results show that THY as a viable alternative to be used in citrus canker management

Endophytes of Brazilian Medicinal Plants with Activity against Phytopathogens

Plant diseases caused by phytopathogens are responsible for significant crop losses worldwide. Resistance induction and biological control have been exploited in agriculture due to their enormous potential. In this study, we investigated the antimicrobial potential of endophytic fungi of leaves and petioles of medicinal plants Vochysia divergens and Stryphnodendron adstringens located in two regions of high diversity in Brazil, Pantanal, and Cerrado, respectively. We recovered 1,304 fungal isolates and based on the characteristics of the culture, were assigned to 159 phenotypes. One isolate was selected as representative of each phenotype and studied for antimicrobial activity against phytopathogens. Isolates with better biological activities were identified based on DNA sequences and phylogenetic analyzes. Among the 159 representative isolates, extracts from 12 endophytes that inhibited the mycelial growth (IG) of Colletotrichum abscissum (≥40%) were selected to expand the antimicrobial analysis. The minimum inhibitory concentrations (MIC) of the extracts were determined against citrus pathogens, C. abscissum, Phyllosticta citricarpa and Xanthomonas citri subsp. citri and the maize pathogen Fusarium graminearum. The highest activity against C. abscissum were from extracts of Pseudofusicoccum stromaticum CMRP4328 (IG: 83% and MIC: 40 μg/mL) and Diaporthe vochysiae CMRP4322 (IG: 75% and MIC: 1 μg/mL), both extracts also inhibited the development of post-bloom fruit drop symptoms in citrus flowers. The extracts were promising in inhibiting the mycelial growth of P. citricarpa and reducing the production of pycnidia in citrus leaves. Among the isolates that showed activity, the genus Diaporthe was the most common, including the new species D. cerradensis described in this study. In addition, high performance liquid chromatography, UV detection, and mass spectrometry and thin layer chromatography analyzes of extracts produced by endophytes that showed high activity, indicated D. vochysiae CMRP4322 and P. stromaticum CMRP4328 as promising strains that produce new bioactive natural products. We report here the capacity of endophytic fungi of medicinal plants to produce secondary metabolites with biological activities against phytopathogenic fungi and bacteria. The description of the new species D. cerradensis, reinforces the ability of medicinal plants found in Brazil to host a diverse group of fungi with biotechnological potential

Aplicação da biomassa Saccharomyces cerevisiae como agente adsorvente do corante Direct Orange 2GL e os possíveis mecanismos de interações adsorbato/adsorvente

RESUMO Os efluentes têxteis liberam grandes quantidades de resíduos de corantes no meio ambiente, poluindo e alterando todo o ecossistema aquático. Além da poluição visual os compostos possuem alta toxicidade, quando não tratado corretamente podem gerar bioacumulação na biota. A levedura Saccharomyces cerevisiae, comumente utilizada como biocatalizador nas indústrias, é um possível adsorvente, devido à estrutura química composta pela parede celular, contendo grupos amino sítio ativo de possíveis interações com os grupamentos sulfônicos pertencentes aos corantes reativos, cuja comercialização compreende em escala mundial. Para tanto, foi realizado um estudo de remoção do corante reativo Direct Orange 2GL pelo método de adsorção, utilizando analises em espectrofotômetro de UV-Vis, mediante a diferentes concentrações de biomassa de S. cerevisiae e valores de pH em solução. O experimento foi analisado a partir do gráfico de isotermas de adsorção, visando à capacidade máxima de adsorção do corante na parede celular da levedura a partir do tratamento matemático usando como modelo as equações de Langmuir e Freundlich e suas linearizações. Os experimentos ressaltaram os possíveis mecanismos de interações químicas, entre adsorbato/adsorvente, podendo apresentar formação em monocamadas ou multicamadas a partir do coeficiente de correlação relativo mediante a influência do valor de pH. As analises em espectrofotômetro UV-Vis, exibiram eficiência no decréscimo dos valores de absorvância em relação ao valor no pico de onda máximo, com resultados de 0,063 absorvância, sendo este um valor aceitável para o padrão de absorvância permitido no descarte de corante. Desse modo, a utilização de biomassa de S. cerevisiae propicia resultados relevantes mesmo a baixas concentrações desde que ajustado os valores de pH em solução

Electrolytic treatment and biosurfactants applied to the conservation of Eugenia uniflora fruit

Abstract Microorganisms are the primary responsible for food poisoning and food spoilage. The purpose of this study was to evaluate different fruit washing methods with tap water, electrolyzed water and rhamnolipids solution produced by Pseudomonas aeruginosa LBI, in order to inhibit microbial growth. The tested organism was Eugenia uniflora. The fruits were washed and periodically inoculated into culture media to evaluate and count the colonies on the fruit surface. It was also observed the deterioration level of the fruits after each treatment. The results showed that treatment with rhamnolipids were the most efficient, inhibiting the growth of fungi and bacteria. The electrolyzed water proved to be very efficient in bacterial inhibition at the initial time, but in the final time it did not present any inhibitory effect. The electrolyzed water was also not effective in eliminating fungus. Washing with tap water was the less efficient treatment of all. The only treatment that showed an increased durability has been with rhamnolipids, increasing shelf life by up to two days. Thus rhamnolipids are the most recommended method for fruits sanitation

Metabolomic- and molecular networking-based exploration of the chemical responses induced in citrus sinensis leaves inoculated with xanthomonas citri

Citrus canker, caused by the bacterium Xanthomonas citri subsp. citri (X. citri), is a plant disease affecting Citrus crops worldwide. However, little is known about defense compounds in Citrus. Here, we conducted a mass spectrometry-based metabolomic approach to obtain an overview of the chemical responses of Citrus leaves to X. citri infection. To facilitate result interpretation, the multivariate analyses were combined with molecular networking to identify biomarkers. Metabolite variations among untreated and X. citri-inoculated Citrus samples under greenhouse conditions highlighted induced defense biomarkers. Notably, the plant tryptophan metabolism pathway was activated, leading to the accumulation of N-methylated tryptamine derivatives. This finding was subsequently confirmed in symptomatic leaves in the field. Several tryptamine derivatives showed inhibitory effects in vitro against X. citri. This approach has enabled the identification of new chemically related biomarker groups and their dynamics in the response of Citrus leaves to Xanthomonas infection

Image_1_Oregano essential oil and its main components Thymol and Carvacrol as alternatives to control citrus canker.pdf

Plant Essential Oils and their constituents are well-known for their properties as antimicrobial agents and are labeled as Generally Recognized as Safe (GRAS), prompting studies around their usage in the control of food-borne microorganisms and phytopathogens. In this study, we evaluated Oregano Essential Oil (OEO), Thymol (THY) and Carvacrol (CAR) for the control of Xanthomonas citri subsp. citri (X. citri). In vitro antibacterial assays revealed that CAR and THY inhibit X. citri growth at the concentrations of 100 µg.mL-1 and 114 µg.mL-1, lower than OEO (136 µg.mL-1). Bactericidal effects were observed at 400 µg.mL-1 for OEO and 200 ug.mL-1 for CAR and THY. Investigating potential cellular targets for the compounds showed that after 30 minutes of exposure up to 84% of the cells had their membranes disrupted, implicating the membrane as the primary target. Phytotoxicity evaluations using Lactuca sativa and Solanum lycopersicum seeds showed an acute toxic effect in all treatments above 200 µg.mL-1, except for OEO and THY in S. lycopersicum at lower concentrations. Regarding their protective effect on citrus leaves, CAR showed no effect when compared to the untreated control (0.39 and 0.50 lesions per cm2, respectively). OEO and THY were able to reduce significantly citrus canker symptoms (0.18 and 0.11 lesions per cm2, respectively). In addition, no toxic effects were observed on citrus leaves in all treatments. THY inhibits X. citri growth and the development of citrus canker lesions. These results show that THY as a viable alternative to be used in citrus canker management.</p