The size-controllable preparation of chitosan/silver nanoparticle composite microsphere and its antimicrobial performance.

The control of chitosan/silver nanoparticle composite microsphere (CAgMs) size is crucial for tuning its function. In the current work, monodisperse organically-modified CAgMs with controllable size were synthesized using a two-step method. The fine-tuning of the microsphere size was confirmed by many reaction parameters while the cross-linking agent was the key research object. Through physical and thermodynamic analysis, we found the cross-linking agent-induced smaller size, higher silver concentration, more heightened glass transition temperature and stronger hydrogen bond network. The as-prepared microspheres exhibited strong bacteriostasis and fresh-keeping function depending on cross-linking agent concentration. The phenomenon is believed to be derived from the difference in microorganism adsorption and killing ability from induced varying specific surface area and encapsulated silver content. Our current work highlights the size-controllable preparation of CAgMs, and based on our findings, small size CAgMs can be a promising candidate in the field of antibacterial and fruit preservation applications.

Wickerhamiella dianesei f.a., sp. nov. and Wickerhamiella kurtzmanii f.a., sp. nov., two yeast species isolated from plants and insects.

Six yeast strains representing two novel Wickerhamiella species were isolated from plants and insects collected in Costa Rica, Brazil, and French Guiana. They belong to a subclade containing Wickerhamiella domercqiae and Wickerhamiella bombiphila, and differ by approximately 12 % in the D1/D2 sequences of the large subunit rRNA gene from these species. The intergenic spacer (ITS) regions of the two novel species differ by around 19 and 27 %, respectively, from those of W. domercqiae. The novel species exhibit 5 % divergence in the D1/D2 sequences among them (around 4 % in the ITS). The names Wickerhamiella dianesei f.a., sp. nov. and Wickerhamiella kurtzmanii f.a., sp. nov. are proposed to accommodate these species, for which a sexual cycle has not been observed. Wickerhamiella dianesei was isolated from the stingless bee, Trigona fulviventris, collected in an Asteraceae flower in Costa Rica, and from leaves of Sabicea brasiliensis (Rubiaceae) and a flower of Byrsonima crassifolia (Malpighiaceae) in Brazil. Wickerhamiellsa kurtzmanii was isolated from a flower of Ipomoea batatoides (Convolvulaceae) in Costa Rica, the surface of a fruit of B. crassifolia in Brazil, and flowers in French Guiana. The type strains are Wickerhamiella dianesei UWOPS 00-107.1T (=CBS 14185=NRRL Y-63789; Mycobank number MB 827008) and Wickerhamiella kurtzmanii UWOPS 00-192.1T (=CBS 15383=NRRL Y-63979; MB 827011).

Phytochemistry and antibacterial activity of aqueous andhydroalcoholic extracts of three medicinal plants against foodpathogens / Fitoquímica e atividade antibacteriana de extratos aquosos e hidroalcoólicos de trêsplantas medicinais contra patógenos de alimentos

This study aimed to characterize the phytochemical compositions of three medicinal Brazilian plants’ leaves and bast extracts, and to determine their antibacterial activity on three foodborne and waterborne bacterial pathogens. Parkia platycephala, Pouteria ramiflora and Lophanthera lactescens leaves and basts were collected and aqueous and hydroalcoholic extracts were prepared. Qualitative screening of the phytochemical extracts was performed with three replicates and in triplicate in order to identify the bioactive compounds. The Minimal Inhibitory Concentration and Minimal Bactericide Concentration were determined by microdilution in broth and Escherichia coli, Salmonella typhimurium and Staphylococcus aureus growth was observed on agar plates. Phytochemical composition analysis allowed for the identification of anthraquinones, catechins, saponins, tannins, sesquiterpenlactones and other lactones in the three plants’ leaves and bast aqueous and hydroalcoholic extracts. Eighty-three percent of the plant extracts showed antibacterial activity against S. aureus, and P. platycephala extracts were the only ones that inhibited E. coli and S. typhimurium growth. The present study contributes significantly to the phytochemical composition characterization of three plant species commonly used in Brazilian traditional medicine. The plant extracts’ in vitro antibacterial activity was demonstrated and catechins present in the extracts are, most likely, the bioactive compounds responsible for this action.

Este estudo objetivou caracterizar a composição fitoquímica dos extratos de folhas e das entrecascas de três plantas medicinais brasileiras e determinar a sua atividade antimicrobiana contra três patógenos bacterianos de alimentos. Foram elaborados extratos aquosos e hidroalcoólicos, por meio de folhas e de entrecascas de Parkiaplatycephala, Pouteriaramiflora e Lophantheralactescens. O estudo qualitativo dos extratos foi realizado com três réplicas, em triplicata, para permitir a identificação dos compostos bioativos. A Concentração Inibitória Mínima e a Concentração Bactericida Mínima foram determinadas por microdiluição contra Escherichia coli, Salmonella typhimurium e Staphylococcus aureus. A análise da composição fitoquímica permitiu identificar antraquinonas, catequinas, saponinas, taninas, sesquiterpenlactonas e outras lactonas nos extratos aquosos e hidroalcoólicos das folhas e das entrecascas das três plantas. Oitenta e três porcento dos extratos das plantas apresentaram atividade antibacteriana contra S. aureus. Os extratos de P. platycephala foram os únicos que inibiram o crescimento de E. coli e S. typhimurium. Este estudo contribui significativamente para a caracterização da composição fitoquímica de três espécies de plantas, frequentemente, utilizadas na medicina tradicional brasileira. A atividade antibacteriana, in vitro, dos extratos das plantas foi demonstrada, e as catequinas são, provavelmente, o composto bioativo responsável por essa atividade.

Molecular phylogeny and biotechnological potential of bacterial endophytes associated with Malpighia emarginata.

Acerola (Malpighia emarginata) is a shrub native to tropical and subtropical climates, which has great commercial interest due to the high vitamin C content of its fruit. However, there are no reports of the endophytic community of this plant species. The aim of this study was to verify the genetic diversity of the leaf endophytic bacterial community of two varieties (Olivier & Waldy Cati 30) of acerola, and to evaluate their biotechnological ability by assessing their in vitro control of pathogenic fungi and the enzymatic production of cellulase, xylanase, amylase, pectinase, protease, lipase, esterase, and chitinase. In total, 157 endophytic bacteria were isolated from the leaves of two varieties of the plant at 28° and 37°C. Phylogenetic analysis confirmed the molecular identification of 58 bacteria, 39.65% of which were identified at the species level. For the first time, the genus Aureimonas was highlighted as an endophytic bacterium. Furthermore, 12.82% of the isolates inhibited the growth of all phytopathogens evaluated and at least one of the above-mentioned enzymes was produced by 64.70% of the endophytes, demonstrating that M. emarginata isolates have potential use in biotechnological studies.

Yeasts from native Brazilian Cerrado plants: Occurrence, diversity and use in the biocontrol of citrus green mould.

Yeasts are some of the most important postharvest biocontrol agents. Postharvest oranges frequently deteriorate due to green mould (Penicillium digitatum), which causes significant losses. The aims of this study were to determine the composition and diversity of yeasts on plants of the Brazilian Cerrado and to explore their potential for inhibiting citrus green mould. Leaves and fruit of Byrsonima crassifolia and Eugenia dysenterica were collected from Cerrado conservation areas, and thirty-five yeasts were isolated and identified by sequencing the D1-D2 domain of the rDNA large subunit (26S). The isolates represented the Aureobasidium, Meyerozyma, Candida, and Pichia genera. Three isolates identified as Aureobasidium pullulans exhibited potential for the control of P. digitatum in both in vitro and in vivo tests; these isolates reduced the incidence of disease and increased the storage time of fruit. Aureobasidium. pullulans has immense potential for the biological control of filamentous fungi.

Structure and development of 'witches' broom' galls in reproductive organs of Byrsonima sericea (Malpighiaceae) and their effects on host plants.

Galls are anomalies in plant development of parasitic origin that affect the cellular differentiation or growth and represent a remarkable plant-parasite interaction. Byrsonima sericea DC. (Malpighiaceae) is a super host of several different types of gall in both vegetative and reproductive organs. The existence of galls in reproductive organs and their effects on the host plant are seldom described in the literature. In this paper, we present a novel study of galls in plants of the Neotropical region: the 'witches' broom' galls developed in floral structures of B. sericea. The unaffected inflorescences are characterised by a single indeterminate main axis with spirally arranged flower buds. The flower buds developed five unaffected brownish hairy sepals and five pairs of elliptical yellow elaiophores, five yellow fringed petals, 10 stamens and a pistil with superior tricarpellar and trilocular ovary. The affected inflorescences showed changes in architecture, with branches arising from the main axis and flower buds. The flower buds exhibited several morphological and anatomical changes. The sepals, petals and carpels converted into leaf-like structures after differentiation. Stamens exhibited degeneration of the sporogenous tissue and structures containing hyphae and spores. The gynoecium did not develop, forming a central meristematic region, from which emerges the new inflorescence. In this work, we discuss the several changes in development of reproductive structures caused by witches' broom galls and their effects on reproductive success of the host plants.

Parâmetros de qualidade de polpas de acerola congeladas / Quality parameters of frozen acerola pulp

A polpa de acerola congelada é um produto acessível, prático e de boa aceitação. Fonte de vitamina C é muito utilizada em lanchonetes, restaurantes e panificadoras. Foram adquiridas em dois supermercados de Rio Branco-AC, 24 amostras, de 1000g cada, de polpas de acerola congeladas de duas marcas A e B no período de outubro a dezembro de 2006, em datas diferentes. O objetivo deste trabalho foi avaliar as características microbiológicas e físico-químicas das polpas, em relação aos parâmetros estabelecidos pela legislação. Foram quantificados os microrganismos: coliformes termotolerantes e totais (NMP/g), bactérias aeróbias mesófilas e bolores e leveduras (UFC/g). Os parâmetros físico-químicos analisados foram: vitamina C mg/100g, °Brix, porcentagem matéria seca, acidez em ácido cítrico porcentagem e pH. Os resultados das análises de coliformes totais indicam que a polpa marca A apresentou 8,35 por cento das amostras positivas 3 a 10 NMP/g e 8,35 por cento na faixa > 1100NMP/g, enquanto na polpa marca B foram encontrados 8,35 por cento de amostras positivas na faixa de 3 a 10 NMP/g.(...)Conclui-se que as polpas A e B atendem a legislação brasileira quanto ao número de coliformes termotolerantes. O teor de Vitamina C foi abaixo do mínimo estabelecido pela legislação, não conformidade 75 por cento e 100 por cento, para as marcas A e B, respectivamente, inferindo-se que as polpas foram processadas a partir de matérias-primas procedentes de lotes diferentes, provável adulteração com água, armazenamento inadequado e deficiência na cadeia do frio.

Byrsonima crassa Niedenzu (IK): antimicrobial activity and chemical study

The methanolic extract of leaves from Byrsonima crassa, a Brazilian medicinal plant, was analyzed by CC and HPLC. Four constituents were isolated and identified as quercetin, methyl gallate, (-)-epigallocatechin gallate and quercetin-3-O-(2-galloyl)-a-L-arabinopyranoside. The methanolic and hydromethanolic extract, as well as fractions, were evaluated regarding their possible antimicrobial activity using in vitro methods. Results showed that both extracts and fractions exhibited significant antimicrobial activity against all tested strains

Nuclear and mitochondrial rDNA variability in Crinipellis perniciosa from different geographic origins and hosts.

Genetic variability in Crinipellis perniciosa, the causal organism of witches' broom disease in Theobroma cacao, was determined in strains originating from T. cacao and other susceptible host species Heteropterys acutifolia and Solanum lycocarpum in Brazil, in order to clarify host specificity and geographical variability. RFLP analysis of the ribosomal DNA ITS regions (rDNA ITS), and the mitochondrial DNA small subunit ribosomal DNA gene (mtDNA SSU rDNA) did not reveal any genetic variability in 120 tested strains, possibly serving only as species level markers. Genetic variability was observed in the ribosomal DNA IGS spacer region, in terms of IGS size, RFLPs and sequence data. Phylogenetic analyses (using CLUSTAL W, PHYLIP and TREEVIEW) indicated considerable differences between C. perniciosa strains from T. cacao and those from H. acutifolia (85-86%) and S. lycocarpum (95-96%). Sequence differences also indicated that C. perniciosa from T. cacao in Bahia is less variable (98%) when compared to the pathogen on T. cacao in Amazonas (97-98%), perhaps reflecting a recent introduction to T. cacao in Bahia.