Aphicidal activity of Bacillus amyloliquefaciens strains in the peach-potato aphid (Myzus persicae)

Myzus persicae Sulzer (Hemiptera: Aphididae), is a generalist cosmopolitan insect that infests more than 400 plant species of 40 different families and is one of the major pests infesting potato crops. It causes direct damage and also spread plant viruses. The intensive use of synthetic insecticide to control aphids has led to resistant populations. Therefore, there is a need to develop biopesticides for effective control that minimizes environmental hazards. The bacteria Bacillus amyloliquefaciens is recognized as a producer of a variety of bioactive compounds. The aim here was to evaluate the aphicidal effect of B. amyloliquefaciens strains, CBMDDrag3, PGPBacCA2, and CBMDLO3, and their metabolites on the mortality and fecundity of M. persicae. Cells suspensions, heat-killed cell suspensions, cell-free supernatants, or isolated lipopeptide fractions from B. amyloliquefaciens strains were offered to aphids through artificial diets. The isolated lipopeptide fractions composed mainly of kurstakins, surfactins, iturins, and fengycins, when were administrated through diets, had no aphicidal effect against M. persicae. However, aphids fed on diets with whole cell suspensions and its cell-free supernatant of all three bacteria strains resulted in 100% mortality of adult aphids and nymphs. Specially, B. amyloliquefaciens CBMDLO3, has an effective aphicidal effect on M. persicae, used both bacterial cells and their metabolites. Moreover, heat-killed cells of B. amyloliquefaciens CBMDLO3 also had aphicidal action, although the aphid mortality was lower than on diet with living bacteria. Therefore, these results propose that B. amyloliquefaciens, could function as a novel eco-friendly biopesticide for the control of M. persicae.Fil: López-Isasmendi,Guadalupe. Universidad Nacional de Salta. Facultad de Ciencias Naturales; ArgentinaFil: Alvarez, Adriana Elisabet. Universidad Nacional de Salta. Facultad de Ciencias Naturales; ArgentinaFil: Petroselli, Gabriela. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Centro de Investigaciones en Hidratos de Carbono. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Centro de Investigaciones en Hidratos de Carbono; ArgentinaFil: Erra Balsells, Rosa. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Centro de Investigaciones en Hidratos de Carbono. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Centro de Investigaciones en Hidratos de Carbono; ArgentinaFil: Audisio, Marcela Carina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Salta. Instituto de Investigaciones para la Industria Química. Universidad Nacional de Salta. Facultad de Ingeniería. Instituto de Investigaciones para la Industria Química; Argentin

Novel antibacterial bioactive glass nanocomposite functionalized with tetracycline hydrochloride

To prevent the high frequency of wound infections, anti-bacterial agents can be loaded onto composites. In the present study, the antibiotic tetracycline hydrochloride (TC)was incorporated, for the first time, in collagen type I membranes coated with nano-sized SiO2-CaOP2O5 bioactive glass (n-BG) obtained by a sol-gel chemical route. Collagen membranes coated with n-BG were immersed in simulated body fluid (SBF) containing 0.25, 0.75 or 1.25 mg mL−1 of TC for 48 h at 37∘C following a coprecipitation method. The antibiotic was released in distilledwater at 37∘C for up to 72 h. The antibacterial activity of the composites was evaluated in vitro by the inhibition zone test and plate count method. Two different Staphylococcus aureus strains, S. aureus ATCC29213 and S. aureus ATCC25923, were exposed to the biomaterials. The results showed that the incorporation but not the release of TC was dependent on the initial concentration of TC in SBF. The biomaterials inhibited S. aureus growth, although the efficacy was similar for all the concentrations. The results allow us to conclude that the new composite could have potential in the prevention of wound infections.Fil: Rivadeneira, Josefina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Tecnologías y Ciencias de la Ingeniería "Hilario Fernández Long". Universidad de Buenos Aires. Facultad de Ingeniería. Instituto de Tecnologías y Ciencias de la Ingeniería "Hilario Fernández Long"; ArgentinaFil: Luz, Gisela M.. Universidade Do Minho; PortugalFil: Audisio, Marcela Carina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Salta. Instituto de Investigaciones Para la Industria Química. Universidad Nacional de Salta. Facultad de Ingeniería. Instituto de Investigaciones Para la Industria Química; ArgentinaFil: Mano, Joao F.. Universidade Do Minho; PortugalFil: Gorustovich Alonso, Alejandro Adrian. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Tecnologías y Ciencias de la Ingeniería "Hilario Fernández Long". Universidad de Buenos Aires. Facultad de Ingeniería. Instituto de Tecnologías y Ciencias de la Ingeniería "Hilario Fernández Long"; Argentin

Evaluation of antibacterial and cytotoxic effects of nano-sized bioactive glass/collagen composites releasing tetracycline hydrochloride

Aims: To evaluate the antibacterial efficacy of silicate bioactive glass nanoparticles/collagen composites functionalized with tetracycline hydrochloride (TCH). Methods and Results: Different concentrations of tetracycline hydrochloride (TCH) were incorporated on silicate bioactive glass nanoparticles/collagen composites by dipping these biomaterials for 48 h at 37°C in a solution of simulated body fluid (SBF) plus 0 05, 0 20 or 0 35 mg ml1 of the antibiotic. TCH release was assessed in double-distilled water at 37°C up to 72 h. The antibacterial activity of the samples has been evaluated in two ways: inhibition zone test and plate count method. The experiments were performed in vitro up to 48 h on four staphylococci strains (Staphylococcus aureus ATCC29213, ATCC25923, ATCC6538P and Staphylococcus epidermidis ATCC12228). The new composites were also tested for cytotoxicity on MG-63 human osteosarcoma cells. The results showed that the incorporation and release of TCH was dependent on the initial concentration of TCH in SBF. The biomaterials also inhibited the Staph. aureus cell growth even though the efficacy was similar for all concentration. On the other hand, no cytotoxic effects were found on osteoblast-like cells, even at the highest concentration. Conclusions: Considering all results, it can be concluded that the new composite acts as a suitable bioactive carrier of TCH and could have potential in the prevention of biomaterial related infections. Significance and Impact of the Study: The results suggest a potential application as wound dressing.Fil: Rivadeneira, Josefina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Tecnologías y Ciencias de la Ingeniería "Hilario Fernández Long". Universidad de Buenos Aires. Facultad de Ingeniería. Instituto de Tecnologías y Ciencias de la Ingeniería "Hilario Fernández Long"; Argentina. Universidad Nacional de Salta; ArgentinaFil: Di Virgilio, Ana Laura. Universidad Nacional de La Plata. Facultad de Ciencias Exactas; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata; ArgentinaFil: Audisio, Marcela Carina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Salta. Instituto de Investigaciones para la Industria Química. Universidad Nacional de Salta. Facultad de Ingeniería. Instituto de Investigaciones para la Industria Química; ArgentinaFil: Boccaccini, A. R.. University of Erlangen-Nuremberg; AlemaniaFil: Gorustovich Alonso, Alejandro Adrian. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Tecnologías y Ciencias de la Ingeniería "Hilario Fernández Long". Universidad de Buenos Aires. Facultad de Ingeniería. Instituto de Tecnologías y Ciencias de la Ingeniería "Hilario Fernández Long"; Argentina. Universidad Nacional de Salta; Argentin

Draft genome sequences of Lactobacillus salivarius A3iob and Lactobacillus johnsonii CRL1647, novel potential probiotic strains for honeybees (Apis mellifera L.)

This report describes the draft genome sequences of Lactobacillus salivariusA3iob and Lactobacillus johnsonii CRL1647, probiotic strains isolated from thegut of honeybee Apis mellifera workers. The reads were generated by a wholegenomesequencing (WGS) strategy on an Illumina MiSeq sequencer and were assembledinto contigs with total sizes of 2,054,490 and 2,137,413 bp for the A3ioband CRL1647 strains, respectively. The draft genome sequences of L. salivarius A3iob and L. johnsonii CRL1647 will be useful for further studies of the specific genetic features of these strains and for understanding the mechanisms of their probiotic properties.Fil: Audisio, Marcela Carina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Salta. Instituto de Investigaciones para la Industria Química. Universidad Nacional de Salta. Facultad de Ingeniería. Instituto de Investigaciones para la Industria Química; ArgentinaFil: Albarracín, Leonardo Miguel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Centro de Referencia para Lactobacilos; Argentina. Universidad Nacional de Tucumán; ArgentinaFil: Torres, María Julia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Salta. Instituto de Investigaciones para la Industria Química. Universidad Nacional de Salta. Facultad de Ingeniería. Instituto de Investigaciones para la Industria Química; ArgentinaFil: Saavedra, Maria Lucila. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Centro de Referencia para Lactobacilos; ArgentinaFil: Hebert, Elvira Maria. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Centro de Referencia para Lactobacilos; ArgentinaFil: Villena, Julio Cesar. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Centro de Referencia para Lactobacilos; Argentin

45S5 Bioglass® concentrations modulate the release of vancomycin hydrochloride from gelatin-starch films: evaluation of antibacterial and cytotoxic effects

The aim of this work was to evaluate the release profile of vancomycinhydrochloride (VC), as well as the degradation, in vitro antistaphylococcal effect and cytotoxicity in MG-63 osteoblast-like cells of gelatin–starch (GS) films added with different concentrations of microparticles of the bioactive glass 45S5 (m-BG). The biomaterials were obtained through the gel-casting method. Four different composites were prepared at four different weight percentages of m-BG: 0, 5, 10, and 15 %. Glutaraldehyde 0.25 wt% (GA) was used as the cross-linker. The composites were characterized by scanning electron microscopy and the in vitro degradation of the filmswas studied bymeasuring thewater uptake and weight loss. The drug release kinetics was quantified spectrophotometrically. The inhibition zone test and the plate count method were used to evaluate the antibacterial activity of the samples. Three staphylococcus strains were evaluated: Staphylococcus aureus ATCC6538, S. aureus ATCC29213, and Staphylococcus epidermidis ATCC12228. Cytotoxicity effects were evaluatedthrough the MTT assay.The addition of m-BG to GS films showedno effects on the amount of water uptake, but led to an increase in the weight loss over time, even with m-BG content. The release rate of VC was also affected by the increasing concentration of m-BG in the composite films.However, the antibacterial effects of the composites were not improved by this modulation. All composites strongly inhibited staphylococcal cells with similar strength. On the other hand, liquid extracts from the composites resultedin cytotoxic effects onMG-63 osteoblastlike cells due to the presence of GA, but not to the concentration of VC or m-BG.Facultad de Ciencias Exacta

Gram-Positive Bacteria with Probiotic Potential for the Apis mellifera L. Honey Bee: The Experience in the Northwest of Argentina

Apis mellifera L. is one of the most important natural pollinators of significant crops and flowers around the world. It can be affected by different types of illnesses: american foulbrood, nosemosis, varroasis, viruses, among others. Such infections mainly cause a reduction in honey production and in extreme situations, the death of the colony. Argentina is the world’s second largest honey exporter and the third largest honey producer, after China and Turkey. Given both the prominence of the honey bee in nature and the economic importance of apiculture in Argentina and the world, it is crucial to develop efficient and sustainable strategies to control honey bee diseases and to improve bee colony health. Gram-positive bacteria, such as lactic acid bacteria, mainly Lactobacillus, and Bacillus spp. are promising options. In the Northwest of Argentina, several Lactobacillus and Bacillus strains from the honey bee gut and honey were isolated by our research group and characterized by using in vitro tests. Two strains were selected because of their potential probiotic properties: Lactobacillus johnsonii CRL1647 and Bacillus subtilis subsp. subtilis Mori2. Under independent trials with both experimental and commercial hives, it was determined that each strain was able to elicit probiotic effects on bee colonies reared in the northwestern region of Argentina. One result was the increase in egg-laying by the queen which therefore produced an increase in bee number and, consequently, a higher honey yield. Moreover, the beneficial bacteria reduced the incidence of two important bee diseases: nosemosis and varroosis. These results are promising and extend the horizon of probiotic bacteria to the insect world, serving beekeepers worldwide as a natural tool that they can administer as is, or combine with other disease-controlling methods.Fil: Audisio, Marcela Carina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Salta. Instituto de Investigaciones para la Industria Química. Universidad Nacional de Salta. Facultad de Ingeniería. Instituto de Investigaciones para la Industria Química; Argentin

Inhibitory activity of surfactin, produced by different Bacillus subtilis subsp. subtilis strains, against Listeria monocytogenes sensitive and bacteriocin-resistant strains

Three surfactin-producing Bacillus subtilis strains, C4, M1 and G2III, previously isolated from honey and intestines from the >Apis mellifera L. bee, were phylogenetically characterized at sub-species level as B. subtilis subsp subtilis using gyrA gene sequencing. The antagonistic effect of surfactin was studied against seven different Listeria monocytogenes strains, 6 of which were resistant to bacteriocins. Surfactin showed anti-Listeria activity against all 7 strains and a dose of 0.125 mg/mL of surfactin was enough to inhibit this pathogen. Surfactin sintetized by B. subtilis subsp. subtilis C4 inhibited the pathogen in lower concentrations, 0.125 mg/mL, followed by G2III and M1 with 0.25 and 1 mg/mL, respectively. In particular, a dose of 0.125 mg/mL reduced the viability of L. monocytogenes 99/287 RB6, a bacteriocin-resistant strain, to 5 log orders. Surfactin assayed maintained anti-Listeria activity within a pH range of between 2 and 10, after heat treatment (boiling for 10 min and autoclaving at 121 ºC for 15 min) and after treatment with proteolytic enzymes. These results suggest that surfactin can be used as a new tool for prevention and the control of L. monocytogenes in different environments, for example, in the food industry.Fil: Sabate, Daniela Constanza. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Salta. Instituto de Investigación para la Industria Química (i); ArgentinaFil: Audisio, Marcela Carina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Salta. Instituto de Investigación para la Industria Química (i); Argentin

Inhibition of Bacillus cereus strains by antimicrobial metabolites from Lactobacillus johnsonii CRL1647 and Enterococcus faecium SM21

Bacillus cereus is an endospore-forming, Gram-positive bacterium able to cause food-borne diseases. Lactic acid bacteria are known for their ability to synthesize organic acids and bacteriocins, but the potential of these compounds against B. cereus has been scarcely documented in food models. The present study has examined the effect of the metabolites produced by Lactobacillus johnsonii CRL1647 and Enterococcus faecium SM21 on the viability of select B. cereus strains. Furthermore, the effect of E. faecium SM21 metabolites against B. cereus strains has also been investigated on a rice-food model. L. johnsonii CRL1647 produced 128 mmol/L of lactic acid, 38 mmol/L of acetic acid and 0.3 mmol/L of phenyl-lactic acid. These organic acids reduced the number of vegetative cells and spores of the B. cereus strains tested. However, the antagonistic effect disappeared at pH 6.5. On the other hand, E. faecium SM21 produced only lactic and acetic acid (24.5 and 12.2 mmol/L, respectively) and was able to inhibit both vegetative cells and spores of the B. cereus strains, at a final fermentation pH of 5.0 and at pH 6.5. This would indicate the action of other metabolites, different from organic acids, present in the cell-free supernatant. On cooked rice grains, the E. faecium SM21 bacteriocin(s) were tested against two B. cereus strains. Both of them were significantly affected within the first 4 h of contact; whereas B. cereus BAC1 cells recovered after 24 h, the effect on B. cereus 1 remained up to the end of the assay. The lactic acid bacteria studied may thus be considered to define future strategies for biological control of B. cereus.Fil: Soria, María Cecilia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Salta. Instituto de Investigación Para la Industria Química (i); ArgentinaFil: Audisio, Marcela Carina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Salta. Instituto de Investigación Para la Industria Química (i); Argentin

Bacteriocin-like substance produced by Lactobacillus salivarius subsp. salivarius CRL1384 with anti-Listeria and anti-Salmonella effects

Lactobacillus salivarius subsp. salivarius CRL1384 was isolated from the crop of a broiler chick and it was selected because of its lactic acid and other inhibitory substances production against Listeria monocytogenes, Listeria spp., Enterococcus hirae, Salmonella enterica serovarieties Gallinanun, Pullorum, Enteritidis and Typhimurium. The antimicrobial substance showed to be different from organic acids and hydrogen peroxide. It was produced by L. salivarius CRL1384 not only in the presence of glucose but also of complex carbohydrates such as sucrose, maltose, molasses and brown sugar. Besides, this strain was bile salt resistant and maintained its property in the presence of 0.3% w/v. The chemical nature of the compound revealed that it was heat resistant (121°C for 15 min) and completely lost its activity after treatment with different proteolytic enzymes. It was not affected by lipase but a-amylase reduced its action and this effect was carbohydrate dependent. A bacteriocin solution of 200 AU m -1 had a bactericidal effect on both List. monocytogenes and Sal. Enteritidis cells after 24 h of contact. The information for this bacteriocin production is encoded at chromosomal level. All these properties are very interesting and valuable and could turn this strain into a potential component of a poultry probiotic supplement. © 2010 Academic Journals Inc.Fil: Audisio, Marcela Carina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Salta. Instituto de Investigaciones para la Industria Química. Universidad Nacional de Salta. Facultad de Ingeniería. Instituto de Investigaciones para la Industria Química; ArgentinaFil: Apella, Maria Cristina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Centro de Referencia para Lactobacilos; Argentina. Universidad Nacional de Tucumán; Argentin

Lactobacillus johnsonii CRL1647, isolated from Apis mellifera L. bee-gut, exhibited a beneficial effect on honeybee colonies

Lactobacillus johnsonii CRL1647, isolated from the intestinal tract of a honeybee and selected due to its high lactic acid production, was assayed as a monoculture on bee colony performance. It was delivered to the bees on a one litre of 125 g/l sugar-cane syrup with a final concentration of 10 5 cfu/ml lactobacilli. The bees accepted the new nourishment, which was consumed within 24-48 h and was administered in two independent trials (every 14-15 days for 3 consecutive months in one case, and once a month for 13 consecutive months in the other). From late spring - early summer (2008) the photo-records and statistical analyses revealed significant differences in the open and the operculated brood areas in the treated group compared with the control. This stimulation was observed after the first administration of the lactobacilli and maintained throughout. Also, a higher number of bees were measured in the treated group (54%) and the control (18%) with respect to the initial bees' number. Furthermore, honey storage was higher, 40% and 19%, for the treated and control groups, respectively. From December 2008 to December 2009, a similar situation was observed even though, in this trial, the lactobacilli cells were administered once a month. The in vivo results of this study are promising and indicate that a L. johnsonii CRL1647 supplement to beehives favours mainly open and operculated brood areas, demonstrating a stronger stimulation of egg-laying and will become a natural product which will assist the beekeeper both in colony management and the creation of late nuclei and/or bee packages due to its beneficial effects in the beehive colony. © 2011 Wageningen Academic Publishers.Fil: Audisio, Marcela Carina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Salta. Instituto de Investigaciones para la Industria Química. Universidad Nacional de Salta. Facultad de Ingeniería. Instituto de Investigaciones para la Industria Química; ArgentinaFil: Benitez Ahrendts, Marcelo Rafael. Universidad Nacional de Jujuy. Facultad de Ciencias Agrarias; Argentin