Ana Paula Guedes Frazzon

Functional analysis of Arabidopsis genes involved in mitochondrial iron–sulfur cluster assembly

Machinery for the assembly of the iron–sulfur ([Fe–S]) clusters that function as cofactors in a wide variety of proteins has been identified in microbes, insects, and animals. Homologs of the genes involved in [Fe–S] cluster biogenesis have recently been found in plants, as well, and point to the existence of two distinct systems in these organisms, one located in plastids and one in mitochondria. Here we present the first biochemical confirmation of the activity of two components of the mitochondrial machinery in Arabidopsis, AtNFS1 and AtISU1. Analysis of the expression patterns of the corresponding genes, as well as AtISU2 and AtISU3, and the phenotypes of plants in which these genes are up or down-regulated are consistent with a role for the mitochondrial [Fe–S] assembly system in the maturation of proteins required for normal plant development.

Molecular analysis of the iap gene of Listeria monocytogenes isolated from cheeses in Rio Grande do Sul, Brazil

The polymorphic region sequences in the iap gene were analyzed in 25 strains of Listeria monocytogenes isolated from cheeses in the state of Rio Grande do Sul, and compared with reference strains. This investigation distinguished two clusters of L. monocytogenes: I (20 strains) and II (5 strains).

Coagulase-Positive Staphylococci Isolated from Chicken Meat: Pathogenic Potential and Vancomycin Resistance

Coagulase-positive staphylococci (CPS) cause staphylococcal food poisoning. Recently, these bacteria have received increasing attention due to their potential role in the dissemination of antibiotic resistance markers. The present study aimed to evaluate coagulase-positive staphylococci counts, species distribution, enterotoxin genes prevalence, and the antibiotic resistance profile of CPS isolated from in natura chicken meat. Fifteen frozen and 15 chilled industrialized, uncooked chicken parts or entire carcasses were used. Staphylococcal counts revealed that frozen chicken meat samples displayed the lowest CPS count compared with chilled chicken meat samples (p<0.01). Staphylococcus aureus (62%) was the most common species, followed by S. intermedius, S. delphini, and S. schleiferi subsp. coagulans (10% each) and S. hyicus (8%). The polymerase chain reaction identification of sea, seb, sec, sed, and see genes revealed that 70% of the isolates harbored at least one enterotoxin gene, with sea and sed being the most frequently encountered ones. Two of the 50 investigated strains harbored three different enterotoxin genes. A high frequency of isolates resistant to penicillin, teicoplanin, oxacillin, and clindamycin was observed, and 80% of CPS were found to be resistant to at least one of the 11 tested antimicrobials. Vancomycin-resistant S. aureus and S. intermedius showed minimum inhibitory concentrations of 512 and 64 μg/mL, respectively. These isolates might indicate the dissemination of vancomycin resistance in the community and imply food safety hazards.

Antibiotic resistance and enterotoxin genes in Staphylococcus sp. isolates from polluted water in Southern Brazil

The aim of this study was to evaluate the species distribution, antibiotic-resistance profile and presence of enterotoxin (SE) genes in staphylococci isolated from the Dilúvio stream in South Brazil. Eighty-eight staphylococci were identified, 93.18% were identified as coagulase-negative (CNS) and 6.82% coagulase-positive (CPS). Fourteen Staphylococcus species were detected and the most frequently were Staphylococcus cohnii (30.48%) and S. haemolyticus (21.95%). Resistance to erythromycin was verified in 37.50% of the strains, followed by 27.27% to penicillin, 12.50% to clindamycin, 6.81% to trimethoprim-sulfamethoxazole, 5.68% to chloramphenicol and 2.27% to norfloxacin. None of the investigated strains showed gentamicin and ciprofloxacin resistance. The strains were tested for the presence of sea, seb, sec, sed and see genes by PCR and only CNS strains (43.18%) showed positive results to one or more SE genes. The scientific importance of our results is due to the lack of data about these topics in polluted waters in Brazil. In conclusion, polluted waters from the Dilúvio stream may constitute a reservoir for disseminating antibiotic-resistance and enterotoxin into the community. In addition, the detection of staphylococci in the polluted waters of the Dilúvio stream indicated a situation of environmental contamination and poor sanitation conditions.

Enterococcus species diversity in fecal samples of wild marine species as determined by real-time PCR

Analyses using culture-independent molecular techniques have improved our understanding of microbial composition. The aim of this work was to identify and quantify enterococci in fecal samples of wild marine species using real-time quantitative PCR. Seven Enterococcus species were examined in fecal DNA of South American fur seals (Arctocephalus australis), Subantarctic fur seals (Arctocephalus tropicalis), green turtles (Chelonia mydas), Magellanic penguins (Spheniscus magellanicus), snowy-crowned tern (Sterna trudeaui), white-backed stilt (Himantopus melanurus), white-chinned petrels (Procellaria aequinoctialis), red knot (Calidris canutus), and black-browed albatross (Thalassarche melanophris). All Enterococcus species evaluated were detected in all fecal samples of wild marine species, with a concentration ranging between 106 and 1012 copies/ng of total DNA. Differences in the enterococci distribution were observed. Enterococcus faecalis and Enterococcus mundtii were most abundant in marine mammals. Enterococcus faecalis was frequent in green turtle, Magellanic penguin, snowy-crowned tern, red knot, and black-browed albatross. Enterococcus hirae and Enterococcus gallinarum showed elevated occurrence in white-backed stilt, and Enterococcus faecium in white-chinned petrel. This study showed highest diversity of enterococci in feces of wild marine species than currently available data, and reinforced the use of culture-independent analysis to help us to enhance our understanding of enterococci in gastrointestinal tracts of wild marine species.

Antimicrobial Resistance Profiles in Enterococcus spp. Isolates From Fecal Samples of Wild and Captive Black Capuchin Monkeys (Sapajus nigritus) in South Brazil

The environment, human, and animals play an important role in the spread of antibiotic-resistant bacteria. Enterococci are members of the gastrointestinal tracts of humans and animals and represent important reservoirs of antibiotic resistance genes. Until today, few studies have examined antibiotic susceptibility in enterococci isolated from primates. Therefore, the present study investigated species distribution, antibiotic susceptibility, and resistance genes in enterococci isolated from wild and captive black capuchins monkeys (Sapajus nigritus) in Rio Grande do Sul, South Brazil. A total of 24 swabs/fecal samples were collected, including 19 from wild monkeys living in two forest fragments [São Sebastião do Caí (SSC) and Santa Cruz do Sul (SCS)], and five in captive [Parque Zoológico da Fundação Zoobotânica (ZOO)], between August 2016 and November 2017. Fifteen colonies were randomly selected from each sample. Enterococci were identified by MALDI-TOF, tested for susceptibility to 12 antibiotics; and screened for tet(S), tet(M), tet(L), msrC, and erm(B) genes by PCR. Two-hundred ninety-six enterococci were isolated (SSC n = 137; SCS n = 86; ZOO n = 73) and differences in Enterococcus species distribution were detected on three monkey groups, with low abundance in SCS (1 - D = 0.2), followed by ZOO (1 - D = 0.68), and SSC (1 - D = 0.73). The enterococci frequently recovered include the following: Enterococcus faecalis (42.6%), E. hirae (29.1%), and E. faecium (15.9%). Antibiotic-nonsusceptible was observed in 202 (67.9%) strains. The rate of non-susceptibility to rifampicin, tetracycline, erythromycin, nitrofurantoin, chloramphenicol, and ampicillin was 46%, 26%, 22% and 19%, 13%, 0.3%, and 0.3%, respectively. All strains were susceptible to vancomycin, streptomycin, gentamycin, and linezolid. Forty-three (14.52%) isolates were identified as multidrug resistant (MDR), and the highest number of MDR enterococci were E. faecium recovered from wild monkeys living close to a hospital and water treatment plant. Elevated rates of antibiotic resistance genes msrC and tet(L) were isolates from ZOO. In conclusion, differences in the frequency of enterococci species, antibiotic-nonsusceptible and antibiotic resistance genes in all groups of monkeys were identified. These data suggest that anthropogenic activities could have an impact in the resistome of primate gut enterococci communities.

DIVERSIDADE DE BACTÉRIAS GRAM-POSITIVAS PRESENTES NO PESCADO E NO CONVÉS DE BARCOS PESQUEIROS APORTADOS NO MUNICÍPIO DE PASSO DE TORRES (SC)

O pescado e um alimento de excelente valor nutritivo; entretanto, e muito perecivel, necessitando de condicoes sanitarias adequadas desde a sua captura ate a comercializacao. Objetivou-se, neste estudo, determinar a presenca de populacoes bacterianas em pescado desde a sua captura ate a entrega ao distribuidor. As amostras foram coletadas em diferentes pontos: no conves do barco pesqueiro, no pescado e no peixe armazenado no momento do desembarque. Um total de 95 micro-organismos isolados foram identificados atraves de tecnicas tradicionais, provas bioquimicas e sequenciamento do 16S rDNA. As bacterias identificadas foram: Aerococcus viridans, Bacillus spp., Brochothrix thermosphacta, Leifsonia aquaticum, Exiguobacterium aurantiacum, Marinococcus halotolerans, Micrococcus luteus, Rhodococcus corynebacterioides, Staphylococcus aureus, S. epidermidis, Salinicoccus alkaliphilus, S. roseus, Streptococcus iniae e Vagococcus fluvialis. Os micro-organismos isolados apontaram uma diversidade bacteriana ligada a influencia de fatores de origem marinha, humana e de contaminacao ambiental, que podem ser

Antimicrobial compounds produced by Enterococcus spp. isolates from fecal samples of wild South American fur seals

The aims of this study were to identify bacteriocinogenic activity in 13 enterococci isolated from fecal samples of wild South American (Arctocephalus australis) and Subantarctic fur seals (Arctocephalus tropicalis); to determine the physicochemical characteristics and antimicrobial spectrum of antimicrobial compounds against Gram-positive and Gram-negative bacteria; and to evaluate the presence of bacteriocin structural genes by PCR. Out of 13 enterococci screened for antimicrobial activity, five enterococci showed activity against Listeria monocytogenes ATCC 35152, an important pathogen linked to food. Of these, only the E. mundtii strain J5 maintained the activity after the pH was adjusted (pH 6.5). The activity of antimicrobial compounds from the E. mundtii strain J5 (ACs-J5) was lostxa0after proteolytic enzyme treatment; however, the activity was maintained after heat, pH (acidic and basic conditions) and chemical treatment. ACs-J5 showed narrow spectrum activity. Only the mundticin KS gene was detected in the J5 strain and no plasmid was present. In conclusion, the properties presented by ACs-J5 make it a valuable biopreservative in food industries in avoiding pathogenic microorganisms such as L. monocytogenes and it should be a good candidate for probiotic application. n n Key words: Antimicrobial compounds, Enterococcus mundtii, wild fur seal, antilisterial activity.