Resumo
The success of in vitro cultivation of plant species depends on factors associated with the induction and control of morphogenesis regarding the regeneration of shoots and roots in the organogenesis process, such as the culture medium composition. Thus, the objective of this study was to investigate if theconcentration of growth regulators in culture medium interferes with the in vitro morphogenesis of gypsophila. 'Golan' cultivar was subjected to three culture media (M), which constituted the study treatments: M1) Murashige and Skoog (MS) medium without the addition of growth regulators; M2) MS + 1 mg L-1of benzylaminopurine (BAP) + 0.05 mg L-1of naphthaleneacetic acid (NAA); M3) MS + 0.05 mg L-1BAP + 1 mg L-1NAA. After 45 days, the multiplication rate, plant height and root length were evaluated. The results showed that plantlets produced in M2 medium had a higher multiplication rate. Also, plantlets produced in M1 and M3 media showed higher shoot height and root length. It is concluded that there is a difference in the in vitromorphogenesis of gypsophila according to the concentration of growth regulators in the micropropagation medium.(AU)
O sucesso do cultivo in vitro de espécies vegetais depende de fatores associados à indução e ao controle da morfogênese quanto à regeneração de brotos e raízes no processo de organogênese, a exemplo da composição de meio de cultura. Assim, o objetivo do estudo foi investigar se a concentração de reguladores de crescimento em meio de cultura interfere na morfogênese in vitrode gipsofila. A cultivar 'Golan' foi submetida a três meios de cultura (M), que constituíram os tratamentos do estudo: M1) meio Murashige e Skoog (MS) sem adição de reguladores de crescimento; M2) MS + 1 mg.L-1de benzilaminopurina (BAP) + 0.05 mg.L-1de ácido naftalenoacético (ANA); M3) MS + 0.05 mg.L-1BAP + 1 mg.L-1de ANA. Após 45 dias avaliou-se a taxa de multiplicação, altura de plantas e comprimento de raízes. Os resultados mostraram que plântulas produzidas no meio M2 tiveram maior taxa de multiplicação. Ainda, plântulas produzidas nos meios M1 e M3 apresentaram maior altura de parte aérea e comprimento de raízes. Conclui-se que há diferença na morfogênese in vitrode gipsofila de acordo com a concentração de reguladores de crescimento em meio de cultura na micropropagação.(AU)
Assuntos
Reguladores de Crescimento de Plantas/análise , Caryophyllaceae/crescimento & desenvolvimento , Morfogênese , Técnicas In Vitro/métodosResumo
Listeria monocytogenes is a pathogenic bacterium that can contaminate food and cause public health problems due its ability to form biofilms and resistance to sanitizers, it is responsible for sanitary and economic losses in food producing establishments. The difficulties in controlling biofilms and increasing resistance to traditional antibacterial agents is motivating studies of alternative potential biological agents for the control of pathogenic biofilms, among which lactic acid bacteria (LABs) are included. The objective of this work was to evaluate the activity of LABs against Listeria monocytogenes biofilm formation on polystyrene plates, a surface commonly used in the food industry. Lyophilized commercial strains of Bifidobacterium animalis, Lactobacillus fermentum, Lactobacillus plantarum, Lactobacillus salivaris and Lactobacillus acidophilus were used. The strain of Listeria monocytogenes (L4) was isolated from polystyrene mats from a poultry slaughterhouse cutting room and demonstrated the ability to attach to microplates and resistance to sanitizers (sodium hypochlorite and hydrogen peroxide) at all times, temperatures and tested surfaces. The antimicrobial activity of LABs was evaluated by the agar diffusion method. The LABs that presented action on Listeria monocytogenes were selected for the inhibition and/or removal of biofilms in microplates, and all experiments were carried out in triplicate. Only Bifidobacterium animalis and Lactobacillus plantarum demonstrated action against Listeria monocytogenes in the agar diffusion assays and were selected for inhibition and competition assays. Furthermore, competition of LABs against Listeria monocytogenes adhesion was evaluated. There was no significant difference between LABs and L. monocytogenes, alone or in combination, at temperatures of 30ºC and 37ºC in the Listeria monocytogenes inhibition assays on polystyrene surface. The lactic acid bacteria evaluated did not demonstrate inhibition of L. monocytogenes adhesin testes with optical density visualization, however, it was possible to identify a reduction in L. monocytogenes counts with the application of Bifidobacterium animals and Lactobacillus plantarum in the testes of competition against biofilm formation. In competition tests Bifidobacterium animalis and Lactobacillus plantarum have an injunction in Listeria monocytogenes, indicating that these lactic acid bacteria can retard Listeria biofilm formation on polystyrene surfaces and thus help control the pathogen in the food industry. A potential mechanism to control biofilm adhesion and formation of pathogens for nutrients and fixation on surfaces, multiplication factors and surfaces are a challenge in controlling biofilms of pathogenic microorganisms, alternative measures to traditional methods for inactivating pathogens and biofilm formers bacteria are necessary. In this sense, lactic acid bacteria generate high levels of bacteriocin and are effective in inhibiting the biofilm of pathogenic bacteria, however, our study did not reveal this. We verified that Bifidobacterium animalis and Lactobacillus plantarum have an inhibitory action on Listeria monocytogenes, indicating that these lactic acid bacteria can be used to delay the formation of biofilms by Listeria on polystyrene surfaces, helping to control this pathogen in food industry.(AU)
Assuntos
Animais , Contaminação de Alimentos/prevenção & controle , Biofilmes/efeitos dos fármacos , Ácido Láctico/antagonistas & inibidores , Listeria monocytogenes/isolamento & purificação , Antibacterianos/análise , Poliestirenos , ListerioseResumo
A campilobacteriose é uma zoonose emergente de origem alimentar causada por bactérias do gênero Campylobacter. Vários fatores dificultam o isolamento deste patógeno em amostras naturalmente contaminadas, por isso devem ser utilizadas metodologias normalizadas bem como meios de cultura com desempenho adequado, prevenindo a ocorrência de resultados falso negativos. Assim, avaliou-se a performance de meios de cultura recomendados pelas ISO 10272-1 para detecção de Campylobacter spp. com testes de seletividade e produtividade em culturas puras e o desempenho destes meios em amostras de carne de frango artificialmente contaminadas. Cepas ATCC de C. coli e C. jejuni e dos interferentes S. aureus, E. coli e Proteus mirabilis foram inoculadas nos meios indicados pelas normas oficiais e posteriormente inoculados em amostras fortificadas. Os meios testados, tanto em culturas puras quanto em amostras fortificadas, tiveram desempenho satisfatório, mostrando boa seletividade e produtividade, permitindo que os laboratórios optem pela combinação de meios com melhor performance para isolamento e identificação de Campylobacter spp. em amostras naturalmente contaminadas.(AU)
Campylobacteriosis is an emerging foodborne zoonotic disease caused by bacteria of the genus Campylobacter. Several factors hinder the isolation of this pathogen in naturally contaminated samples; therefore, standardized methods as well as high performance culture media should be used to avoid false negative results. Thus, the present study assessed the performance of culture media recommended by ISO 10272- 1 for the detection of Campylobacter spp. using selectivity and productivity testing in pure cultures and the efficiency of these media in artificially contaminated, samples. ATCC strains of C. coli and C. jejuni and of the interfering organisms S. aureus, E. coli and Proteus mirabilis were inoculated into the media indicated by official standards and later inoculated into enriched samples. The media tested both in pure cultures and in enriched samples yielded satisfactory results, with good selectivity and productivity, there by allowing laboratories to combine high performance methods for the isolation and identification of Campylobacter spp. in naturally contaminated samples.(AU)