Esterco de animais de criação pode conter microrganismos patogênicos, o que representa um risco para a saúde animal e a humana se o esterco não for adequadamente tratado ou descartado. Determinou-se o tempo necessário para a eliminação de Escherichia coli Shiga toxigenica (STEC) não O157 em esterco ovino composto, obtido de fezes frescas de ovelhas naturalmente colonizadas com cepas STEC não O157 que apresentavam os genes stx1/ stx2. Foram utilizados dois sistemas de compostagem, aerado e não aerado, em experimentos realizados na cidade de Dracena, estado de São Paulo. Todas as semanas, durante sete semanas, uma amostra de compostagem proveniente de seis pontos diferentes na leira, nos dois sistemas, foi coletada e semeada para a determinação da presença de E. coli, da presença de genes de virulência nas células, bem como da sensibilidade dessas células a 10 drogas antimicrobianas. Em cada amostragem, a temperatura da leira foi analisada. Células de STEC não O157 sobreviveram por 49 dias nos dois sistemas de compostagem. E. colinão STEC com um alto grau de resistência a antibióticos foi recuperada ao longo de todo o período de compostagem. Não foi possível estabelecer relação entre a presença de genes de virulência e a resistência a antibióticos. A presença de genes de virulência e a resistência a múltiplos antibióticos em E. coli representam um risco potencial para o espalhamento desses genes na cadeia alimentar humana, o que é motivo de grande preocupação.

Livestock manure may contain pathogenic microorganisms which pose a risk to the health of animal or humans if the manure is not adequately treated or disposed of. To determine the fate of Shiga toxigenic Escherichia coli (STEC) non O157 in composted manure from naturally colonized sheep, fresh manure was obtained from animals carrying bacterial cells with stx1/ stx2 genes. Two composting systems were used, aerated and non-aerated, and the experiments were done in Dracena city, São Paulo State. Every week, for seven weeks, one manure sample from six different points in both systems was collected and cultured to determine the presence of E. coli, the presence of the virulence genes in the cells, and also the susceptibility to 10 antimicrobial drugs. The temperature was verified at each sampling. STEC non-O157 survived for 49 days in both composting systems. E. coli non-STEC showing a high degree of antibiotic resistance was recovered all long the composting period. No relationship was established between the presence of virulence genes and antibiotic resistance. The presence of virulence genes and multiple antibiotic resistances in E. coli implicates a potential risk for these genes spread in the human food chain, which is a reason for concern.

The efficiency of the Polymerase Chain Reaction (PCR) combined with selective enrichment broth was compared with the standard microbiological techniques for detection of Salmonella Dublin in fecal samples of 10 to 15-days-old Holstein calves, experimentally infected with 10(8) CFU of Salmonella Dublin. Seventy-six fecal samples were analyzed using PCR associated with selenite cystine (SC) and Muller-Kauffmann tetrathionate (TMK) broths and standard microbiological techniques. Regardless of the selective enrichment broth used, the standard microbiological techniques were significantly better than PCR in detection of positive samples of Salmonella Dublin. However, the simultaneous use of both techniques provided detection of a larger number of positive samples. The SC broth was the best option as selective enrichment in both techniques.

Salmonella enterica serovar Gallinarum (SG) is an intracellular pathogen of chickens. To survive, to invade and to multiply in the intestinal tract and intracellularly it depends on its ability to produce energy in anaerobic conditions. The fumarate reductase (frdABCD), dimethyl sulfoxide (DMSO)-trimethylamine N-oxide (TMAO) reductase (dmsABC), and nitrate reductase (narGHIJ) operons in Salmonella Typhimurium (STM) encode enzymes involved in anaerobic respiration to the electron acceptors fumarate, DMSO, TMAO, and nitrate, respectively. They are regulated in response to nitrate and oxygen availability and changes in cell growth rate. In this study mortality rates of chickens challenged with mutants of Salmonella Gallinarum, which were defective in utilising anaerobic electron acceptors, were assessed in comparison to group of bird challenged with wild strain. The greatest degree of attenuation was observed with mutations affecting nitrate reductase (napA, narG) with additional attenuations induced by a mutation affecting fumarate reductase (frdA) and a double mutant (dmsA torC) affecting DMSO and TMAO reductase.

RESUMO O presente trabalho teve como objetivo caracterizar geneticamente 1.073 isolados de Bacillus thuringiensis, de três coleções brasileiras, provenientes da UNESP, Jaboticabal, da ESALQ/ Piracicaba e da EMBRAPA. Sete Lagoas, analisando os tipos de genes cry1 apresentados pelos isolados. Para isso, foram elaborados oligonucleotídeos iniciadores a partir de 16 regiões conservadas e 4 regiões não conservadas das seqüências de cada uma das 16 subclasses do gene cry1. Essas seqüências foram amplificadas por PCR e a presença de amplicons para cada subclasse foi calculada em porcentagem por gene e por coleção. Nessa análise, 55,7% dos isolados apresentaram amplificação para o gene cry1, e as subclassescry1Aa, cry1Ab, cry1Ac, cry1Ad, cry1Ae, cry1Af, cry1Ag, e cry1Bf, cry1Ca e cry1Fa estão presentes em alta proporção de isolados, variando de 43,4% a 54,9%. Verificou-se que existe uma distribuição das subclasses dentro do banco de isolados de B. thuringiensis em estudo, com maior porcentagem de isolados portadores dos genes cry1Ab (42,12%) e com menor porcentagem de representantes da subclasse cry1Db (0,6%). A variabilidade gênica, nas coleções analisadas, destaca as coleções de Jaboticabal e Piracicaba como fontes de isolados promissores para uso em programas de Controle Biológico de pragas da ordem Lepidoptera. A coleção de Sete Lagoas, na qual as freqüências das subclasses estudadas foram relativamente baixas (abaixo de 20%), destaca somente o gene cry1Ab, presente em 38,5% dos isolados desta coleção.

ABSTRACT The aim of this work was to genetically characterize 1,073 isolates of B. thuringiensis, from three Brazilian collections – UNESP/Jaboticabal, ESALQ/Piracicaba and EMBRAPA/Sete Lagoas– with the main emphasis on the analysis of the cry1 gene types presented by these isolates. To achieve this purpose, oligonucleotide primers were designed based on 16 conserved and 4 unconserved regions of the corresponding sequences from each one of the 16 subclasses of the cry1 set of genes and used in PCR amplification assays. These sequences were amplified and the presence of amplicons for each subclass was evaluated in terms of percentage of gene type per bacterial collection. As a result, 55.7% of the isolates reacted to the primer Gral cry1, and the subclasses cry1Aa, cry1Ab, cry1Ac, cry1Ad, cry1Ae, cry1Af, cry1Ag, cry1Bf, cry1Ca and cry1Fa were detected in high percentages among the isolates ranging from 43.4 to 54.9%. A subclass distribution was observed among the set of isolates from these collections, with the greater percentage of isolates harboring the cry1Ab (42.12%) and the lowest percentage for thecry1Db subclass (0.6%). The genetic variability of the analyzed bacterial collections seems to indicate the ESALQ/Piracicaba and the UNESP/Jaboticabal subsets as sources of promising isolates for the control of Lepidoptera pest insects. For the EMBRAPA/Sete Lagoas subset of isolates, in which the evaluated subclasses frequencies were considered low (below 20%), the cry1B was the most frequently observed gene type present in 38.5% of the isolates.

RESUMO Com o objetivo de determinar a existência de variabilidade genética em plantas de trapoeraba (Commelina benghalensis L.), foram coletadas plantas em 10 diferentes regiões de quatro Estados do Brasil (SP, MG, MT e MS). Esses acessos foram submetidos a um estudo de variabilidade genética por meio de RAPD com 35 iniciadores arbitrários, os quais geraram 84 bandas polimórficas. Observou-se a formação de 2 grupos principais e o índice de identidade genética entre os acessos estudados apresentou-se acima de 59%. Os acessos de Arceburgo e Taiaçú foram os que apresentaram a maior similaridade genética (95%). Campo Novo do Parecis foi o acesso que mais se distanciou dentro do filograma. Observou-se que a variabilidade genética pela análise de dados dos marcadores RAPD foi pequena entre os acessos de trapoeraba estudados, a qual não se mostrou relacionada à distribuição geográfica, pois nos 2 grupos existem acessos coletados em diferentes Estados.

ABSTRACT Aiming to observe the existence of genetic variability in plants of tropical spiderwort (Commelina benghalensis L.), plants were collected from 10 different regions of 4 Brazilian states (SP, MG, MT and MS). Theseaccessions were analyzed by RAPD molecular markers using 35 arbitrary primers which revealed 84 polymorphic bands. The establishment of 2 main groups with genetic identity above 59% was observed. Theaccessions from Arceburgo and Taiaçú were the ones with greater genetic similarity (95%). The accession from Campo Novo do Parecis was the one with less similarity in terms of the phylogram. The genetic variability observed analyzing the RAPD markers was small among the studied tropical spiderwort accessions, with no relation to the geographic region where the accessions were collected, since the two groups formed involve accessions from different states.

RESUMO Este trabalho teve por objetivo analisar o uso da prensa francesa para se adquirir material genético de estafilococos e detectar possíveis genes de resistência cromossomais e plasmidiais aos antimicrobianos oxacilina, gentamicina, canamicina e vancomicina. O método da difusão de discos em ágar foi realizado, inicialmente, para 50 linhagens de estafilococos e a susceptibilidade antimicrobiana foi confirmada por meio de Reação em Cadeia da Polimerase (PCR). Os resultados obtidos pelo antibiograma constataram alta susceptibilidade para gentamicina e canamicina (4%) e oxacilina (8%). Todas as linhagens foram susceptíveis à vancomicina. O DNA bacteriano foi obtido por lise física a partir da prensa francesa. Os genes mecA e aph3’IIIa foram detectados no cromossomo dos estafilococos e o gene aac(6’) Ie + aph (2") foi observado tanto no cromossomo como no plasmidio destas bactérias. Pelos resultados pode-se concluir que a metodologia utilizada para a extração de DNA genômico, por meio da prensa francesa, foi barata e eficiente, pois possibilitou a detecção por PCR e a localização, por ultracentrifugação, de genes de resistência em estafilococos.

ABSTRACT The main of the present study was analyze the use of a french press device to obtain genetic material from staphylococci and to detect genes involved with chromosomal and plasmid resistance to the following antimicrobial drugs: oxacillin, gentamicin, kanamycin and vancomycin. The agar disc diffusion method was conducted initially for 50 strains and the bacterial susceptibility was confirmed by means of PCR reactions. The results from the antibiogram method revealed high sensibility to gentamicin and kanamycin (4%) and oxacillin (8%). All strains were susceptible to vancomycin. The DNA from the bacteria was obtained by means of physical lyses using a french press device. The genes mecA and aph’3 – IIIa were detected on the staphylococci chromosome and the gene aac(6’)Ie + aph(2’’) was observed either in the chromosome and in the plasmid content of the staphylococci analyzed. Based on the obtained results one can conclude that the methodology used to extract the genomic genetic material using the french press device was efficient and allowed a simple method to detect by PCR and to locate by ultracentrifugation, the staphylococci antibiotic resistance genes.

PCR has been used to analyze the distribution of REP (Repetitive Extragenic Palindromic) and ERIC (Enterobacterial Repetitive Intergenic Consensus) sequences (rep-PCR) found within the genome of the bacterium Bacillus thuringiensis, with the purpose to analyze the genetic similarities among 56 subspecies samples and 95 field isolates. The PCR products were analyzed by EB-AGE (ethidium bromide-agarose electrophoresis) and then submitted to banding comparisons, based on the Phyllip software algorithm. When the banding similarities were considered for comparison purposes among all the strains, the phylogenic tree patterns varied according to the rep-PCR primers considered, but, from a broader point of view, the ERIC sequences produced better results, which, together with electron microscopy analysis of the released parasporal bodies and colony morphology characteristics, allowed to detect two possible new subspecies of B. thuringiensis.