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BackgroundHoney has been identified as a potential alternative to the widespread use of antibiotics, which are of significant concern considering the emergence of resistant bacteria. In this context, this study aimed to evaluate the antimicrobial activity of honey samples produced by a stingless bee species and by Apis sp. against pathogenic bacteria, as well as to identify the presence of phenolic compounds.MethodsHoney samples from the stingless bee M. compressipes manaosensis were collected twice, during the dry and rainy seasons. Three commercial honey samples from Apis sp. were also included in this study. Two different assays were performed to evaluate the antibacterial potential of the honey samples: agar-well diffusion and broth macrodilution. Liquid-liquid extraction was used to assess phenolic compounds from honey. HPLC analysis was performed in order to identify rutin and apigenin on honey samples. Chromatograms were recorded at 340 and 290 nm.ResultsTwo honey samples were identified as having the highest antimicrobial activity using the agar diffusion method. Honey produced by Melipona compressipes manaosensis inhibited the growth of Staphylococcus aureus, Escherichia coli (0157: H7), Proteus vulgaris, Shigella sonnei and Klebsiella sp. A sample of honey produced by Apis sp. also inhibited the growth of Salmonella paratyphi. The macrodilution technique presented greater sensitivity for the antibacterial testing, since all honey samples showed activity. Flavonoid rutin was identified in the honey sample produced by the stingless bee.ConclusionsHoney samples tested in this work showed antibacterial activity against Gram-positive and Gram-negative bacteria. The results reported herein highlight the potential of using honey to control bacterial growth.

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Beneficial interactions between plants and microorganisms have been investigated under different ecological, physiological, biochemical, and genetic aspects. However, the systematic exploration of biomolecules with potential for biotechnological products from this interaction still is relatively scarce. Therefore, this study aimed the evaluation of the diversity and antimicrobial activity of the endophytic fungi obtained from roots, stems and leafs of Myrcia guianensis (Myrtaceae) from the Brazilian Amazon. 156 endophytic fungi were isolated and above 80% were identified by morphological examination as belonging to the genera Pestalotiopsis, Phomopsis, Aspergillus, Xylaria, Nectria, Penicillium and Fusarium. Fermented broth of those fungi were assayed for antimicrobial activity and four inhibited the growth of Staphylococcus aureus, Enterococcus faecalis, Candida albicans and Penicillium avellaneum. As the strain named MgRe2.2.3B (Nectria haematococca) had shown the most promising results against those pathogenic strains, its fermented broth was fractioned and only its two low polar fractions demonstrated to be active. Both fractions exhibited a minimum bactericidal concentration of 50 μg.mL−1 against S. aureus and a minimum fungicidal concentration of 100 μg.mL−1 against P. avellaneum. These results demonstrate the diversity of fungal genera in M. guianensis and the potential of these endophytic fungi for the production of new antibiotics.

Este é um artigo publicado em acesso aberto (Open Access) sob a licença Creative Commons Attribution, que permite uso, distribuição e reprodução em qualquer meio, sem restrições desde que o trabalho original seja corretamente citado. Estudo da conservação das propriedades nutricionais da polpa de tucumã (Astrocaryum aculeatum) in natura em embalagens a vácuo Study of the conservation of the nutritional properties of in natura Tucumã pulp (Astrocaryum aculeatum) using vacuum packagingResumo O tucumã, também conhecido como tucumã-do-amazonas, é o fruto oriundo da palmeira Astrocaryum aculeatum e possui significativo potencial econômico local. Caracteriza-se como um fruto pouco ácido, com baixos teores de açúcar, alto teor de β-caroteno e alto valor energético. O objetivo deste trabalho foi estudar a conservação das propriedades nutricionais da polpa de tucumã in natura, a partir da utilização de embalagem a vácuo, uma vez que o armazenamento da polpa é realizado de forma inadequada, na maioria dos estabelecimentos comerciais. O potencial antioxidante da polpa durante o armazenamento também foi avaliado. Executaram-se, ao longo de 150 dias, análises de umidade, cinzas, pH, acidez, extrato etéreo, conteúdo energético, crescimento microbiológico, além da atividade antioxidante, pelo método do sequestro do radical DPPH•. As embalagens foram armazenadas sob temperatura de congelamento e resfriamento. Foi constatado que os valores de umidade, cinzas e pH são conservados pela utilização de embalagem a vácuo, em temperatura de congelamento ou resfriamento, durante cinco meses de armazenamento; a acidez foi conservada somente em embalagens a vácuo sob congelamento, por apenas dez dias; os valores de extrato etéreo foram conservados durante três meses de congelamento e um mês de resfriamento, e o valor energético contido na polpa foi conservado por dois meses sob congelamento e dez dias sob resfriamento. Não foi detectada a presença de coliformes e de Salmonella durante cinco meses de armazenamento a vácuo, em amostras congeladas e resfriadas; a atividade antioxidante foi preservada durante dois meses em amostras congeladas, mas não foi mantida em amostras resfriadas. Portanto, a partir deste estudo, foi possível verificar que a utilização de embalagens a vácuo, associada ao congelamento, permite a conservação da maioria das principais características nutricionais da polpa de tucumã in natura, por 30 dias de armazenamento. Ressalta-se, ainda, que esse é um procedimento simples, que pode ser empregado no comércio alimentício local. Palavras-chave: AbstractThe tucumã, also known as Amazonian tucumã, is the fruit obtained from the Astrocaryum aculeatum palm tree, and presents significant local economic potential. It is characterized as a slightly acid fruit, low in sugar, but high in β-carotene and energy. The objective of the present work was to study the conservation of the nutritional properties of in natura tucumã pulp using vacuum packaging, since the pulp is stored inappropriately in most commercial establishments. The ...

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Three sources of food proteins were treated with microbial transglutaminase (EC 2.3.2.13) in order to assess changes in the physicochemical properties of reactivity, solubility, emulsification, and free amino groups of the formed polymers. Samples of lactic casein (LC), isolated soy protein (ISP), and hydrolysed animal protein (HAP), were incubated with the enzyme for one or two hours. LC and ISP showed a reduced solubility of 15% and 24% respectively, with HAP showing no alteration on solubility. Amino nitrogen content was 7%, 3% and 2% reduced for HAP, LC and ISP respectively. LC and ISP demonstrated lower emulsifying activity when they were enzymatically treated but the formed emulsions were stable, contrasting with HAP, which exhibited no changes in emulsifying properties.