Potential of Klebsiella oxytoca for 1,3-propanediol production from glycerol under excess substrate conditions

Glycerol, a by-product of biodiesel, is a source of carbon for the bioproduction of chemical intermediates with high commercial value, such as 1,3-propanediol. One strain of Klebsiella oxytoca, isolated from soil samples, was tested to determine its potential to produce 1,3-propanediol through fermentation of a glycerol solution, under excess substrate conditions. The microbial growth curve was evaluated by optical density reading using a spectrophotometer (600 nm), while glycerol consumption and concentration of the products were determined by high performance liquid chromatography (HPLC) with HPX 87H column (BioRad). Formate, 3-hydroxypropionaldehyde and ethanol were produced in the early hours of fermentation. The increased rate of glycerol consumption and the formation of 1,3-propanediol coincides with formate degradation. This indicates that formate degradation likely works as an alternative means to generate part of the nicotine adenine dinucleotide (NADH) used by the 1,3-propanediol-dehydrogenase enzyme. Yield in mole of product per 100 mol of substrate reached 48.5, which is higher than that of previously investigated K. oxytoca strains.Keywords: Klebsiella oxytoca, glycerol, fermentation, 1,3-propanediol, biodiese

Atividade anti-protozoário in vitro do p-Cimeno sobre Leishmania amazonensis

As doenças tropicais se constituem em um grave problema de saúde pública, por serem negligenciadas e atingirem especialmente as populações mais pobres. Entre os principais problemas mundiais de saúde, a leishmaniose se destaca por apresentar altas taxas de mortalidade. Grandes esforços tem sido empregados na busca por novos medicamentos nas ultimas décadas, sendo o uso da fitoterapia investigado com grande interesse, devido às plantas serem consideradas uma ampla fonte de compostos com potencial biomedicinal. A atividade anti-protozoário da substância p-Cimeno sobre formas promastigotas e amastigotas axênicas de Leishmania amazonensis, foi avaliado. Após 72 horas de cultivo, o p-Cimeno apresentou concentração inibitória de 50% (CI50) igual à 65,0 µg/mL e 55,0 µg/mL sobre as formas promastigotas e amastigotas axênicas, respectivamente. Análises de citotoxicidade do p-Cimeno, foram realizadas por meio do método colorimétrico da sulforodamina-B sobre macrófagos J774G8 e a concentração citotóxica para 50% das células (CC50) foi de 54,0 µg/mL. Os dados obtidos indicam efeito antiparasitário do p-Cimeno sobre Leishmania amazonensis, principalmente sobre sua forma amastigota, sendo considerado potencial candidato para novos estudos contra o parasito

Antibacterial and antibiofilm activity of carvacrol against Salmonella enterica serotype Typhimurium

The present study evaluated the antibacterial and antibiofilm activity of carvacrol against Salmonella Typhimurium. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) were determined and the time-kill curve and scanning electron microscopy (SEM) were performed to evaluate antibacterial activity. Antibiofilm activity was evaluated by quantifying total biomass using crystal violet assay, and metabolic activity was determined using MTT [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide] assay. The action of carvacrol against preformed biofilm on polypropylene and stainless steel was also evaluated by colony counting and SEM. The MIC and MBC was 312 µg mL-1. Carvacrol at MIC and 2 x MIC eliminated cells after 6 and 1 h of treatment, respectively, as exhibited in the time-kill curve. The greatest reduction in biofilm biomass and metabolic activity was 1,719 OD550 and 0,089 OD550 respectively, both at 4 x MIC of carvacrol. In carvacrol treated biofilms of S. Typhimurium on polypropylene, a reduction of 5.12 log was observed with 4 x MIC, while on stainless steel, carvacrol at 4 x MIC reduced bacterial counts by 5 log. The results showed that carvacrol exhibits antibacterial activity and can be used as an alternative for the control of S. Typhimurium biofilms

Atividade antimicrobiana de kefir fermentado com subproduto de uva contra Alicyclobacillus acidoterrestris / Antimicrobial activity of fermented kefir with a byproduction

Alicyclobacillus spp. they are spore-forming bacteria that deteriorate acidic fruit-based drinks, causing economic losses, with A. acidoterrestris being the most studied, responsible for causing sensory changes, especially in orange juice. The use of natural antimicrobial agents in foods can be an option with great advantages for the industry and the consumer. Therefore, the objective of this work was to investigate the antimicrobial activity of extracts fermented by kefir, from a grape by-product, against A. acidoterrestris. Four extracts were prepared with kefir grains, being 1 - grape extract and kefir grains; 2 - grape extract, brown sugar and kefir grains; 3 - grape extract, ultrasound and kefir grains; and 4 - grape extract, ultrasound, brown sugar and kefir grains. The four extracts were fermented at 28 ºC for 7 days. The extracts were centrifuged at 10,000 rpm for 10 min and the supernatant was subjected to membrane filtration (0.22 μm). The minimum inhibitory concentration (MIC) was determined by the serial microdilution technique of extracts of 50 to 0.1% concentration in Bacillus acidoterrestris (BAT) medium. The minimum bactericidal concentration (CBM) was also determined. Structural changes in cells after treatment were evaluated by scanning electron microscopy (SEM). The MIC value capable of inhibiting the visible growth of A. acidoterrestris for all extracts was 1.6%, while the CBM was 50% for extracts 1 and 3, while for extracts 2 and 4 the CBM was 25%. The results show that extracts 2 and 4 obtained better CBM value, possibly because kefir produced more secondary metabolites with the addition of brown sugar, in addition, the use of ultrasound did not interfere. The results of the inhibitory and/or bactericidal concentration indicate that the extracts have activity against A. acidotrrestris

Use of nanoencapsulated curcumin against vegetative cells and spores of Alicyclobacillus spp. in industrialized orange juice

Pathogenic and deteriorating bacteria are a great concern to food safety. In this sense, the present study evaluated the fight against microbial contamination through the use of nanoparticles containing curcumin, in addition to analyzing the physical properties of these nanoparticles. Efficient curcumin encapsulation was determined by Fourier transform infrared spectra evaluation and differential scanning calorimetry. Transmission electron microscopy images showed irregular shaped nanoparticles with broad size distribution (20–250 nm). The antibacterial activity was considered satisfactory, since curcumin in the form of nanoparticles demonstrated antimicrobial and antibacterial activity superior to curcumin in its free form, against both pathogenic bacteria, such as Staphylococcus aureus (MIC 125 μg/mL), and deteriorates, such as Alicyclobacillus acidoterrestris (MIC 62.5 μg/mL). Since curcumin nanoparticles may be consumed as a food additive, the bioactive properties of the nanoencapsulated curcumin were also evaluated in relation to antioxidant capacity (Thiobarbituric acid reactive substances (TBARS) and oxidative hemolysis inhibition assays) and cytotoxicity against four carcinoma cell lines, as well as two non-tumor cells. As a proof of concept, nanoparticles were incorporated in orange juice, with the juice maintaining satisfactory pH, °Brix, and color stability, during three days of storage (8 °C).This study was financed in part by the Coordenaç˜ao de Aperfeiçoamento de Pessoal de Nível Superior - Brasil (CAPES) - Finance Code 001. The authors thank the “Central Analítica Multiusu´ario da UTFPR Campo Mourão” (CAMulti-CM) for the analyses. Fernanda V. Leimann (process 039/2019) would like to thank Fundação Araucária (CP 15/2017- Programa de Bolsas de Produtividade em Pesquisa e Desenvolvimento Tecnológico) and CNPq (process number 421541/2018-0, Chamada Universal MCTIC/CNPq n◦ 28/2018). The authors are also grateful to the Foundation for Science and Technology (FCT, Portugal) for financial support through national funds FCT/MCTES to CIMO (UIDB/00690/ 2020); L. Barros and C. Pereira also thank FCT, P.I., through the institutional scientific employment program-contract.info:eu-repo/semantics/publishedVersio

Crescimento e esporulação de Alicyclobacillus Acidoterrestris em meio de cultura e em suco de laranja industrializado/ Determination of the growth and sporulation of Alicyclobacillus acidoterrestris in the culture medium and industrialized orange juice

Alicyclobacillus acidoterrestris é microrganismo aeróbio, Gram-positivo, ácido-termorresistente, não patogênico e formador de esporos. Devido a sua capacidade de esporulação, esse microrganismo é frequentemente encontrado em sucos cítricos industrializados, pois sobrevivem a etapas térmicas do processamento, multiplica-se e acarreta a deterioração do produto, devido ao seu metabolismo. Desta maneira, leva ao desenvolvimento de atributos sensoriais indesejáveis no alimento, como a produção de 2,4-dibromofenol e 2-metoxifenol (guaiacol). Dessa forma, representam sério problema para o setor citrícola brasileiro, uma vez que o Brasil é responsável por mais da metade da produção mundial e exportação de suco de laranja. Assim, este trabalho teve como objetivo avaliar o crescimento, enumeração, esporulação de A. acidoterrestris. Foram utilizados no presente estudo o meio de cultura específico (BAT) e o suco de laranja reconstituído (11 °Brix) como meio de cultivo. Realizou-se a curva de crescimento para determinação e enumeração das células vegetativas e da esporulação, foram utilizados o meio BAT, pH 4,0 e suco de laranja reconstituído incubados a 45 ºC nos tempos 0, 3, 6, 9 e 12 horas. Ambos os meios de cultivos avaliados resultaram em valores de contagem de células vegetativa sem função do tempo de incubação. No tempo 0 a contagem foi de 2,301 e 1,699 log UFC/mL no meio BAT e no suco de laranja, respectivamente. Após 12h de incubação a contagem obtida no meio BAT foi de 8 log UFC/mL e 6,279 log UFC/mL no suco de laranja. Nos ensaios efetuados para a quantificação de esporos, onde se utilizou o choque térmico (80 °C/10min), apenas após 9 horas de incubação foi possível obter contagem de células, 4,477 log UFC/mL, esses resultados indicam a germinação de esporos ocorrida devido ao choque. Este mapeamento detalhado auxilia na busca de alternativas para o monitoramento e controle rápido de A. acidoterrestris no processamento industrial, visto que esta espécie está sendo utilizada como indicador de qualidade do suco de laranja

AVALIAÇÃO DA QUALIDADE DA ÁGUA DESTINADA AO CONSUMO HUMANO EM INSTITUIÇÃO DE ENSINODOI: http://dx.doi.org/10.5892/ruvrd.v15i1.3340

A água destinada ao consumo humano nem sempre é de qualidade assegurada. Isso ocorre devido fatores como deficiência no sistema de distribuição de água tratada e no tratamento da mesma. A qualidade da água foi monitorada em 21 pontos (bebedouros, poço e torneira) de uma instituição de ensino na cidade de Maringá, por meio de análises físico-químicas e bacteriológica. Os resultados das análises foram confrontados com padrões de potabilidade da água no Brasil. A presente pesquisa revelou que os metais alumínio, cádmio, chumbo e ferro encontraram-se em concentrações acima do valor máximo permitido e as concentrações de cloro apresentaram-se abaixo do valor mínimo exigido (<0,2 mg/L), dessa forma havendo a presença de coliformes totais. Os resultados obtidos foram insatisfatórios, sendo necessárias ações corretivas para assegurar a qualidade da água destinada ao consumo humano

In vitro antibacterial activity of a 7-O-beta-D-glucopyranosyl-nutanocoumarin from Chaptalia nutans (Asteraceae)

Ethanolic crude extracts from the roots of Chaptalia nutans, traditionally used in Brazilian folk medicine, were screened against Staphylococcus aureus, Escherichia coli, and Pseudomonas aeruginosa by using the disk diffusion test technique. S. aureus with 14 mm inhibition zone was considered susceptible. E. coli and P. aeruginosa without such a zone were considered resistant. As a result of this finding, the ethanolic crude extract was fractionated on silica gel column chromatography into five fractions. The ethyl acetate fraction was active against S. aureus and Bacillus subtilis. Further column chromatography separation of the ethyl acetate fraction afforded 30 fractions, which were assayed against S. aureus. Fractions 16 and 17 showed inhibition zones with S. aureus, indicating the presence of active compounds, and were subjected to purification by repeated preparative thin layer chromatography. The pure compound 7-O-beta-D-glucopyranosyl-nutanocoumarin inhibited B. subtilis and S. aureus at concentrations of 62.5 µg/ml and 125 µg/ml, respectively. The antibacterial property of C. nutans appears to have justified its use for the treatment of wounds, which are contaminated through bacterial infections

In Vitro Antibacterial Activity of a 7-O-b-D-glucopyranosylnutanocoumarin from Chaptalia nutans (Asteraceae)

Ethanolic crude extracts from the roots of Chaptalia nutans , traditionally used in Brazilian folk medicine, were screened against Staphylococcus aureus , Escherichia coli , and Pseudomonas aeruginosa by using the disk diffusion test technique. S. aureus with 14 mm inhibition zone was considered susceptible. E. coli and P. aeruginosa without such a zone were considered resistant. As a result of this finding, the ethanolic crude extract was fractionated on silica gel column chromatography into five fractions. The ethyl acetate fraction was active against S. aureus and Bacillus subtilis . Further column chromatography separation of the ethyl acetate fraction afforded 30 fractions, which were assayed against S. aureus . Fractions 16 and 17 showed inhibition zones with S. aureus , indicating the presence of active compounds, and were subjected to purification by repeated preparative thin layer chromatography. The pure compound 7-O- β -D-glucopyranosyl-nutanocoumarin inhibited B. subtilis and S. aureus at concentrations of 62.5 µ g/ml and 125 µ g/ml, respectively. The antibacterial property of C. nutans appears to have justified its use for the treatment of wounds, which are contaminated through bacterial infections