Antimicrobial activity of characterized Leuconostoc spp. as novel probiotics isolated from Oreochromis spp. (red tilapia) against fish pathogen Edwardsiella tarda

Aims@#This study aimed to isolate and characterize putative new probiotic with antimicrobial properties against common fish pathogens from the gut of Oreochromis spp. (red tilapia). @*Methodology and results@#A total of 28 colonies were isolated from gut of Oreochromis spp. and characterized phenotypically. Eight isolates were selected for probiotic characterization. Temperature, salinity, pH and bile salt tolerance, antibiotic susceptibility and antimicrobial test against selected fish pathogens (Aeromonas hydrophila, Edwardsiella tarda and Staphylococcus aureus subsp. aureus ATCC 25923) were conducted. Characterization studies revealed isolates suited for freshwater environment and exhibited tolerance against wide range of salinity, pH and bile salt. Isolates displayed different antibiotic susceptibility profile, with six exhibited antimicrobial properties against E. tarda. Molecular identification based on 16S rRNA gene sequencing showed 99.44%, 98.59% and 91.21% sequence similarity with Leuconostoc pseudomesenteroides strain 3832T, Leuconostoc lactis strain KCC202369T and Leuconostoc mesenteroides strain 4332T, respectively as compared to known sequence in the GenBank. When identified Leuconostoc spp. were coated on feed pellets, no major decrease in viability over 21 days of storage at 4 °C were observed, with an average of 8 log CFU/mL.@*Conclusion, significance and impact of study@#The characterized species allow further application assessment of the probiotic-supplemented tilapia feed. Host-originated Leuconostoc displayed potential antimicrobial properties against fish pathogen E. tarda. The isolates Leuconostoc is expected to provide protective effect for Oreochromis spp. against edwardsiellosis and to exert beneficial effects more efficiently as compared to commercial probiotics which are not specifically target for Oreochromis spp., thereby indirectly helping fish farmers in achieving economic sustainability and increase affordability of fish.

Caracterización de la composición en proteína, lípidos, energía y perfiles de ácidos grasos en huevos de tilapia roja (Oreochromis spp.) / Characterization of the Protein, Lipid, Energy and Fatty Acid Profile Composition in Red Tilapia (Oreochromis spp.) eggs / Caracterização da composição em proteína, lipídios, energia e perfis de ácidos gordurosos em ovos de tilápia vermelha (Oreochromis spp.)

Luego de considerar el significado de las tilapias en el escenario piscícola nacional, la posibilidad de mejorar los índices de producción es un imperativo técnico y, dentro de estos, focalizar esfuerzos experimentales en la semilla resulta ser una opción estratégica. Con el fin de establecer un referente de base se utilizaron las puestas individuales de 50 hembras de tilapia roja (Oreochromis spp.) para determinar los contenidos en los huevos de proteína (%MS), extracto etéreo (%MS), energía (cal g-1) y los perfiles de ácidos grasos (%), con algunas relaciones de interés analítico. Salvo ciertas variaciones menores, los valores encontrados se ajustan a los registros disponibles para la especie en diferentes estudios, lo que sugiere que las dietas ofrecidas a los reproductores experimentales contienen los mínimos necesarios para asegurar una provisión de nutrientes y energía suficientes para los embriones y las larvas en formación. Se analiza que, como punto de partida, esta serie de datos tiene utilidad para el desarrollo de trabajos destinados a mejorar los estándares de producción de alevinos, considerando que las variaciones en la composición, que pueden ser determinadas sobre los huevos, se pueden utilizar y tienen validez como un indicativo directo de su calidad.

After considering the meaning of tilapia in the national piscicultural scenario, the possibility of improving production rates is a technical imperative and, among these, focusing experimental efforts in the seed turns out to be a strategic option. In order to establish a base model, individual laying of 50 female red tilapia (Oreochromis spp.) were used to determine the content of protein in eggs (%MS), ether extract (%DM), energy (cal g-1) and fatty acid profiles (%) with some relations of analytical interest. Except for minor variations, the values found are consistent with the available records for the species in different studies, suggesting that diets offered to experimental breeders contain the minimum necessary to ensure provision of sufficient energy and nutrients for embryos and larvae in formation. It is analyzed that, as a starting point, this series of data is useful for the development of work to improve the standards of fingerling production, considering that variations in the composition, which can be determined on the eggs, can be used and have validity as a direct indication of its quality.

Depois de considerar o significado das tilápias no cenário da piscicultura nacional, a possibilidade de melhorar los índices de produção é um imperativo técnico e, dentro destes, focalizar esforços experimentais na semente resulta ser uma opção estratégica. Com a finalidade de estabelecer um referente de base, se utilizaram as postas individuais de 50 fêmeas de tilápia vermelha (Oreochromis spp.) para determinar os conteúdos nos ovos de proteína (%MS), extrato etéreo (%MS), energia (cal g-1) e os perfis de ácidos gordurosos (%), com algumas relações de interesse analítico. Com exceção de algumas variações menores, os valores encontrados se ajustam aos registros disponíveis para a espécie em diferentes estágios, o que sugere que as dietas oferecidas aos reprodutores experimentais contêm os mínimos necessários para assegurar uma provisão de nutrientes e energia suficientes para os embriões e as larvas em formações. Analisa-se que, como ponto de partida, esta série de dados tem utilidade para o desenvolvimento de trabalhos destinados a melhorar os padrões de produção de alevinos, considerando que as variações na composição, que podem ser determinadas sobre os ovos, se podem utilizar e têm validade como um indicativo direto de sua qualidade.

Evaluación de la calidad alimentaria de la harina de Lemna obscura como ingrediente en la elaboración de alimento para tilapia roja (Orechromis spp) / Feeding quality evaluation of Lemna obscura meal as ingredients in the elaboration of food for red tilapia (Orechromis spp)

El presente trabajo se realizó con la finalidad de evaluar la calidad nutricional de la harina de lenteja de agua (Lemna obscura) como ingrediente en la elaboración de alimento para tilapia roja (Oreochromis spp.). Se prepararon 3 dietas con niveles de inclusión de 15 por ciento (dieta A), 25 por ciento (dieta B) y 35 por ciento (dieta C) y una dieta control exenta de harina de Lemna. Estas fueron isocalóricas e isoproteicas con un nivel de 30 por ciento de proteína. Además se utilizó una dieta comercial (dieta D), con 40 por ciento de proteína, para compararla con las dietas experimentales. Los alevines se alimentaron durante 10 semanas consecutivas y cada catorce días, se evaluaron los parámetros más importantes como ganancia de peso, alimento consumido, factor de conversión alimentaria (FCA) y la relación eficiencia-proteica (REP). La comparación estadística reveló que no hubo diferencias significativas (P>0,05) en los valores de los resultados finales de la conversión entre las dietas Control A, B, C y D. En relación al peso promedio final, hubo diferencias significativas (P<0,05) entre los peces alimentados con la dieta B, con respecto a la dieta control y dieta comercial. No hubo diferencias significativas entre las dietas experimentales (P>0,05). Se demuestra en este estudio que la dieta con un 25 por ciento de inclusión resultó ser más eficiente en cuánto a los parámetros evaluados que la dieta control. Los excedentes de Lemna crecidos en el lago de Maracaibo o cultivados pueden ser utilizados como harina en las dietas para tilapia roja y representa una alternativa para reducir los costos de alimentación, siempre y cuando se utilice en combinación con otros ingredientes de alto contenido proteico.

The present work was carried out with the purpose to evaluate the nutritional quality of duckweed (Lemna obscura) meal as ingredient in the food elaboration for red tilapia (Oreochromis spp.). Three diets were prepared with inclusion levels of 15 percent (diet A), 25 percent (diet B) and 35 percent (diet C) and a control diet free of Lemna meal. The diets were isocaloric and isonitrogenous with 30 percent of protein. Furthermore, commercial diet (diet D) with 40 percent protein was used to compare with experimental diets. The fingerlings were fed during 10 weeks consecutive and fourteen days, were evaluated the most important parameters as weight gain, consumed food, feed convertion ratio (FCR) and the protein efficiency ratio (PER). The statistical comparison revealed that there were no significant differences (P>0.05) in the values of final results of convertion among diets control, A, B, C and D. In relation to weight average final there were significant differences (P<0.05) among the fish fed with the diet B with respect to the control diet and commercial diet. There were no significant differences among experimental diets (P>0.05). This study showed that diet with inclusion level 25 percent resulted to be more efficient in how much to the evaluated parameters that the diet control. The excesses of Lemna grown in the Maracaibo lake or cultivated can be used as meal in the diets for red tilapia and represents one alternative to reduce the feeding costs, as long as it used in combination with other ingredients of high protein content.

Organochlorine pesticides in lacustrine sediments and tilapias of Metztitlan, Hidalgo, Mexico

The organochlorine pesticides (OP) are very stable molecules, due to this stability; they are very resistant in the environment and highly related to fat tissues with a wide diffusion property and an average time life higher then 10 years. We studied sediments (November 2001, April and June 2002) and organisms collected in April and July (2002) from the lacustric zone of Metzitlán, Hidalgo, Mexico. The analysis was performed according to UNEP/IAEA (1982) (sediments) and UNEP/FAO/IOC/IAEA (1986) (organisms) methods. Three chemical families of organochlorine pesticides were identified and analyzed to determine posible toxicological risk. The principal organochlorine compounds found in sediments were g-HCH, d-HCH, p,p’-DDT and the endosulfan sulfate; these xenobiotics come from agriculture lands near the river and lake, used intensively, and most probably carried by the rain and rain flows into the main water body. In the tilapias tissue, p,p’-DDD y d-HCH were detected. The average concentrations of organochlorine pesticides in sediments were within the internacional limits for freshwater benthonic fauna, although lindane (g-HCH) was near the limit. The fish were above the criteria established in the local legislation (NOM-027-SSA1-1993 y NOM-028-SSA1-1993). Rev. Biol. Trop. 56 (3): 1381-1390. Epub 2008 September 30.

El presente trabajo se llevó a cabo en la cuenca lacustre de Metztitlán, Hgo. Se realizaron tres colectas de sedimentos recientes en noviembre (2001), abril y julio (2002) y dos colectas para organismos en abril y julio (2002). Los análisis se hicieron siguiendo la metodología para sedimentos propuesta por UNEP/IAEA (1982) y para tejido de organismos por UNEP/FAO/IOC/IAEA (1986). Se identificaron y cuantificaron tres familias químicas de plaguicidas organoclorados, para determinar el posible riesgo toxicológico de los sedimentos y de organismos en capturas comerciales. Los principales compuestos clorados en sedimentos fueron el g-HCH, d-HCH, p,p’-DDT y el sulfato de endosulfán; estos xenobióticos provienen de las zonas de cultivos aledañas al río y al lago, con un uso intensivo, probablemente transportados por lluvias y descargas fluviales hacia el cuerpo lacustre y en el tejido de organismos se detectaron principalmente el p,p’-DDD y d-HCH. Las concentraciones promedio de plaguicidas clorados en sedimentos no rebasaron los límites establecidos en los criterios de calidad ambiental internacionales para provocar efectos nocivos en la biota bentónica de los sistemas dulceacuícolas, aunque de manera puntual el lindano (g-HCH) registró niveles cercanos a dichos límites. Las tilapias rebasaron los criterios existentes en las Normas Oficiales Mexicanas (NOM-027-SSA1-1993 y NOM-028SSA1-1993).