Use of five probiotic strains to determine sensitivity in vitro on pathogenic bacteria growth isolated from sick fishes

ABSTRACT Ornamental aquaculture is an activity in clear economic growth, both globally and in Mexico where the development is particularly relevant to freshwater species. Infectious diseases produced by fungus, bacteria and virus are considered one of the principal limitations during the productive process. Between implemented strategies for reduction of antibiotic use, which are "living microorganisms that confer a health benefit to the host if they are given in adequate quantities"; lactic acid bacteria and yeast are among the most common used microorganism in aquaculture. This investigation, prove the effect of isolated probiotic bacteria from the digestive tract of healthy fish, belonging to specie: Bacillus sp., Bacillus laterosporus, Bacillus subtilis, Lactobacillus sp, and Lactococcus lactis, at different dilutions (10 9 ,10 8 , 10 7 ,10 6 , 10 5 and 10 4 ) in vitro growth of pathogenic bacteria: Citrobacter freundii, Enterobacter sakasakii, Klebsiella oxytoca, Proteus vulgaris, and Vibrio fluvialis, isolated from kidney of sick fish, cultured and purified through successive inoculations and identificated by the amplification of gene 16S of rRNA (PCR) using universal primers 8 for. (5'-AGACTTTGATCATGGCTCAG-3') and 1492 rev. (5'-TACGGCTACCTTGTTACGACTT-3') and comparison with GENEBANK sequences base. Probiotic strains were previously isolated from the digestive tract of different healthy fish in the laboratory. In order to perform in vitro challenge tests, pathogenic strains were inoculated three times each in BHI agar boxes at a concentration of 1x10 7 CFU mL -1 and subsequently using the well diffusion method, 70 µL from a suspension with each of the probiotic strains were added. Agar boxes were incubated 24 h at 30ºC to observe the formation of inhibition halos. Obtained values from inhibition halos were transformed to qualitative data with the following premise: halo diameter < 2.0 mm negative effect; halo diameter > 2.0 mm positive effect. In this study, it was determined that probiotic strains B. subtilis was the one that gave better results to inhibit the growth of pathogenic bacteria P. vulgaris, E. sakazakii, V. fluvialis, K. oxytoca and C. freundii in most of used dilutions. Making it a strain with high potential in aquaculture. Key words: Growth, halos, probiotics, bacteria, sensibility. RESUMEN La acuicultura de especies ornamentales es una actividad económica en franco crecimiento, tanto a nivel mundial como en México, en donde tiene particular desarrollo lo correspondiente a especies dulceacuícolas. Las enfermedades infeccionas producidas por hongos, bacterias y virus, están consideradas una de las limitantes principales durante el proceso productivo. Entre las estrategias implementadas para disminuir el uso de antibióticos para el control de patógenos, se encuentra el control biológico mediante el uso de organismos probióticos, los cuales son "microorganismos vivos los cuales, administrados en cantidades adecuadas, confieren un beneficio en la salud del hospedador"; entre los de uso más común en acuicultura se encuentran las lactobacterias y las levaduras. En el presente trabajo, se probó el efecto de bacterias probióticas aisladas del tracto digestivo de peces sanos, pertenecientes a las especies: Bacillus sp., Bacillus laterosporus, Bacillus subtilis, Lactobacillus sp, y Lactococcus lactis, a diferentes diluciones (10 9 ,10 8 , 10 7 ,10 6 , 10 5 y 10 4 ) en el crecimiento in vitro de las bacterias patógenas: Citrobacter freundii, Enterobacter sakasakii, Klebsiella oxytoca, Proteus vulgaris y Vibrio fluvialis, aisladas del riñón de peces enfermos, cultivadas y purificadas a través de resiembras sucesivas e identificadas mediante la amplificación del gen 16S del ARNr (PCR) utilizando los primers universales 8 for. 24 AGACTTTGATCATGGCTCAG-3') y 1492 rev. (5'-TACGGCTACCTTGTTACGACTT-3') y su comparación con la base de secuencias GENEBANK. Las cepas probióticos fueron aisladas previamente del tracto intestinal de diversos peces sanos en el laboratorio. Para llevar a cabo las pruebas de desafío in vitro, las cepas patógenas se sembraron por triplicado en cajas de agar BHI a una concentración de 1x10 7 UFC mL -1 y posteriormente, utilizando el método de difusión en pozos, se adicionaran 70 µL de una suspensión con cada una de las cepas probióticas Las placas se incubaron durante 24 h a 30ºC para observar la formación de halos de inhibición. Los valores obtenidos de los halos de inhibición fueron transformados a datos cualitativos con la siguiente premisa: diámetro halo < 2.0 mm efecto negativo; diámetro de halo > 2.0 mm efecto positivo. En este estudio, se determinó que la cepas probiótica B. subtilis fue la que dio mejores resultados al inhibir el crecimiento de las bacterias patógenas P. vulgaris, E. sakazakii, V. fluvialis, K. oxytoca y C. freundii en la mayoría de las diluciones utilizadas. Por lo que es una cepa con alto potencial en acuicultura

Global distribution patterns provide evidence of niche shift by the introduced African dung beetle Digitonthophagus gazella

The establishment of cattle ranches throughout the world has prompted the release of dung beetles as biological control agents that reduce pasture fouling and control dung‐breeding flies. One of these beetles, Digitonthophagus gazella (Fabricius) (Coleoptera: Scarabaeidae), that is native to southeast Africa, has been introduced into the Americas, Australia, and New Zealand. Distribution records for this species have been used to develop climate models of potential future establishment. Recent studies, however, identify D. gazella as a complex of seven species. Taking into account this revision, and the clear identification of the records belonging to the actual D. gazella, we developed environmental models to identify factors that have contributed to the establishment of this species across regions and habitats. We compared the environmental conditions of D. gazella in its native range against those in the regions where the species has or has not established. Our results indicate that D. gazella is still absent in certain parts of Central and South America and parts of Africa where it could potentially establish. We speculate that its distribution in Africa is limited by competitive exclusion. The introduction of D. gazella in America is relatively recent, such that the full extent of its distribution has probably yet to be realized. In Australia and North America, D. gazella is present in regions not predicted according to its native environmental conditions. This discrepancy may reflect a lack of competitive exclusion, phenotypic plasticity, and/or genetic adaptation. Our analyses suggest that the species has the ability to adapt to a wide range of environmental conditions that are extremely different from those in their native region. The species represents a useful case study to indicate that an introduced species may expand its realized niche beyond what is expected based on apparent environmental limits in the species native range.Appendix S1. Digitonthophagus gazella geographical records included in the analysis.Appendix S2. Explanatory variables deleted in the various phases of the screening analysis and those finally selected. Variance inflation factor (V): variables deleted by having a V value <5 in the geographical background (GB) of the native area of Digitonthophagus gazella. Index (I): variables deleted after applying the instability index to identify those with the highest capacity to discriminate between the environmental conditions in the presence cells against those prevailing in the GB area. F: finally selected variables.The data from New Zealand are courtesy of the Dung Beetle Release Strategy Group (DBRSG) and Landcare Research Manaaki Whenua.A Colciencias Ph.D. scholarship.https://onlinelibrary.wiley.com/journal/157074582021-08-11hj2021Zoology and Entomolog

Description and performance of track and primary-vertex reconstruction with the CMS tracker

A description is provided of the software algorithms developed for the CMS tracker both for reconstructing charged-particle trajectories in proton-proton interactions and for using the resulting tracks to estimate the positions of the LHC luminous region and individual primary-interaction vertices. Despite the very hostile environment at the LHC, the performance obtained with these algorithms is found to be excellent. For tbar t events under typical 2011 pileup conditions, the average track-reconstruction efficiency for promptly-produced charged particles with transverse momenta of p(T) > 0.9GeV is 94% for pseudorapidities of |η| < 0.9 and 85% for 0.9 < |η| < 2.5. The inefficiency is caused mainly by hadrons that undergo nuclear interactions in the tracker material. For isolated muons, the corresponding efficiencies are essentially 100%. For isolated muons of p(T) = 100GeV emitted at |η| < 1.4, the resolutions are approximately 2.8% in p(T), and respectively, 10μm and 30μm in the transverse and longitudinal impact parameters. The position resolution achieved for reconstructed primary vertices that correspond to interesting pp collisions is 10–12μm in each of the three spatial dimensions. The tracking and vertexing software is fast and flexible, and easily adaptable to other functions, such as fast tracking for the trigger, or dedicated tracking for electrons that takes into account bremsstrahlung