Sublethal injury and virulence changes in Listeria monocytogenes and Listeria innocua treated with antimicrobials carvacrol and citral.

The aim of this study was to evaluate the effect of two antimicrobial substances, carvacrol and citral, on Listeria monocytogenes and Listeria innocua cells, as well as possible virulence changes in injured cells, using Caenorhabditis elegans as a model test. The results indicated that the percentage of sublethal damage was higher in L. monocytogenes than in L. innocua. The results of the study carried out by using C. elegans indicated that C. elegans fed in a lawn of L. monocytogenes previously treated with carvacrol showed a loss in life span (p ≤ 0.05) as compared with L. monocytogenes treated with citral, Escherichia coli OP50 as a negative control, and treated and untreated L. innocua. Egg laying was also affected: worms fed in a lawn of treated and untreated L. monocytogenes laid fewer eggs than those fed in a lawn of treated and untreated L. innocua or fed with OP50 as a negative control. Worms fed in a lawn of treated and untreated L. innocua also laid fewer eggs than those fed with OP50 as a negative control. A phenotype named bag of worms and an undescribed new one, "vulva inflammation", were also observed.

Effect of citral and carvacrol on the susceptibility of Listeria monocytogenes and Listeria innocua to antibiotics.

UNLABELLED: The aim of this study was to evaluate the antibiotic susceptibility of Listeria innocua (L. innocua) and Listeria monocytogenes (L. monocytogenes) cells in the presence of citral and carvacrol at sublethal concentrations in an agar medium. The presence of terpenes in the L. monocytogenes and L. innocua culture medium provided a reduction in the minimal inhibitory concentration (MIC) of all the antibiotics tested. These effects were dependent on the concentration of terpenes present in the culture medium. The combination of citral and carvacrol potentiated antibiotic activity by reducing the MIC values of bacitracin and colistin from 32.0 and 128.0 µg ml⁻¹ to 1.0 and 2.0 µg ml⁻¹, respectively. Thus, both Listeria species became more susceptible to these drugs. In this way, the colistin and bacitracin resistance of L. monocytogenes and L. innocua was reversed in the presence of terpenes. Results obtained in this study show that the phytochemicals citral and carvacrol potentiate antibiotic activity, reducing the MIC values of cultured L. monocytogenes and L. innocua. SIGNIFICANCE AND IMPACT OF THE STUDY: Phytochemicals citral and carvacrol potentiate antibiotic activity of erythromycin, bacitracin and colistin by reducing the MIC values of cultured Listeria monocytogenes and Listeria innocua. This effect in reducing the MIC values of the antibiotics tested in both micro-organisms was increased when natural antimicrobials were combined. This finding indicated that the combination among terpenes and antibiotic may contribute in reducing the required dosage of antibiotics due to the possible effect of terpenes on permeation barrier of the micro-organism cell membrane.

Manipulation of the fatty acids composition of poultry meat and giblets by dietary inclusion of two oil sources and conjugated linoleic acid / Mudança na composição de ácidos graxos das vísceras e da carne de aves tratadas com uma dieta contendo ácido linoléico conjugado e duas fontes de óleo

The effect of dietary conjugated linoleic acid (CLA) in association with two vegetable oil sources on the fatty acids of meat and giblets of broiler chickens was evaluated. Two hundred 21-day-old broiler chickens were distributed in a completely randomized factorial design 2 x 5 (two oil sources, soybean or canola oil; and five levels of CLA, 0.0, 2.5, 5.0, 7.5, and 10.0g/kg). The addition of CLA to the diet resulted in an increase (P<0.05) in CLA deposition in the analyzed tissues. CLA supplementation also reduced (P<0.05) the rate of polyunsaturated to saturated fatty acids in thigh, breast, heart, and gizzard. There was interaction of CLA x oil source (P<0.05). The intake of soybean oil, associated with increasing CLA, resulted in an increase in lipid deposition in edible portions as observed by an increase in the overall content of fatty acids, including CLA, while the use of canola oil, associated with increasing CLA in the diet, resulted in a decrease in lipid content in edible portions, specifically regarding that of saturated fat (P<0.05) in breast meat and liver and in the content of monounsaturated fatty acids (P<0.05) in thigh, breast, liver, and gizzard.

Avaliou-se o efeito da suplementação de ácido linoléico conjugado (CLA) associado com duas fontes de óleo na dieta de frangos de corte sobre a composição de ácidos graxos das vísceras e da carne de aves. Duzentos frangos de corte, machos, com 21 dias de idade, foram distribuídos em delineamento inteiramente ao acaso, em arranjo fatorial 2 x 5 (duas fontes de óleo, soja e canola e cinco níveis de CLA, 0,0, 2,5, 5,0, 7,5 e 10,0g/kg). A adição de CLA na dieta resultou em aumento (P<0,05) de sua deposição na carne e nas vísceras de aves. Foi observado decréscimo (P<0,05) na taxa de poliinsaturados:saturados nas carnes da coxa e do peito, no coração e na moela com a suplementação de CLA. Houve interação (P<0,05) CLA x fonte de óleo. O uso de teores crescentes de CLA na dieta contendo óleo de soja na dieta resultou em aumento (P<0,05) no conteúdo lipídico. O contrário foi verificado com a utilização de óleo de canola, especificamente no conteúdo de ácidos graxos saturados (P<0,05) na carne do peito e no fígado e de monoinsaturados (P<0,05) nas carnes do peito e da coxa, fígado e moela.

Effects of microbial phytase on growth and mineral utilisation in broilers fed on maize soyabean-based diets.

1. A 3-week feeding trial with 96 sexed d-old broiler chickens was conducted to examine the effects of microbial phytase supplementation (Natuphos 5000) at 2 dietary energy concentrations on their performance, and the utilisation of nitrogen (N), phosphorus (P), calcium (Ca) and zinc (Zn) and on tibiae ash, Ca, P and Zn concentrations. Four replicate pens (6 birds per pen) of a completely randomised design were used in a 2x2 factorial arrangement of treatments with 2 contents of metabolisable energy (11.72 and 12.55 MJ ME/kg) and 2 additions of phytase (0 and 500 U of microbial phytase/kg). 2. Phytase supplementation significantly improved the utilisation of N, P, Ca and Zn (as a percentage of intake) and increased the concentration of Ca and Zn in the tibiae (P<0.05) because of higher intakes of dry matter, N, P, Ca and Zn. Phytase also significantly reduced the amount of P in the excreta (P<0.05). 3. The AME content of the diet influenced significantly (P<0.05) the excretion of N, P, Ca and Zn and the concentration of P and Ca in tibiae with the birds fed on the high AME diet excreting more minerals and having a smaller percentage of these minerals in their tibiae. However, there were strong interactions between phytase addition and AME in tibia ash and P, with the phytase supplementation producing a higher ash content at the higher AME a and a lower P content at the lower AME.

Efeito da adiçäo de fitase em dietas com dois níveis de energia metabolizável para pintos de corte / Effect of addition of microbial phytase and energy levels on growth and nutrient utilization in broiler chicks

Avaliou-se o efeito da suplementaçäo da fitase comercialmente denominada Natuphos elevado a R 5000 (BASF) sobre a digestibilidade aparente dos nutrientes da dieta, utilizaçäo mineral e desempenho de pintos de corte, de zero a 21 dias de idade. Noventa e seis pintos de um dia de idade foram distribuídos aleatoriamente em um delineamento inteiramente ao acaso, em esquema fatorial 2 x 2, (2800 e 3000kcal EM/kg de raçäo e zero de 500UI/kg fitase de raçäo totalizando quatro tratamentos com quatro repetiçöes cada um (seis aves/repetiçöes). Näo foi observada influência da fitase sobre o desempenho das aves. Entretanto, houve aumento na concentraçäo de cálcio e zinco na tíbia (P<0,05). A fitase reduziu a quantidade de fósforo presente na excretas e aumentou a taxa de retençäo do fósforo, do cálcio, do zinco e do nitrogênio (P<0,05)