Because of its potential to modulate host health, the gut microbiome of captive animals has become an increasingly important area of research. In this paper, we review the current literature comparing the gut microbiomes of wild and captive animals, as well as experiments tracking the microbiome when animals are moved between wild and captive environments. As a whole, these studies report highly idiosyncratic results with significant differences in the effect of captivity on the gut microbiome between host species. While a few studies have analyzed the functional capacity of captive microbiomes, there has been little research directly addressing the health consequences of captive microbiomes. Therefore, the current body of literature cannot broadly answer what costs, if any, arise from having a captive microbiome in captivity. Addressing this outstanding question will be critical to determining whether it is worth pursuing microbial manipulations as a conservation tool. To stimulate the next wave of research which can tie the captive microbiome to functional and health impacts, we outline a wide range of tools that can be used to manipulate the microbiome in captivity and suggest a variety of methods for measuring the impact of such manipulation preceding therapeutic use. Altogether, we caution researchers against generalizing results between host species given the variability in gut community responses to captivity and highlight the need to understand what role the gut microbiome plays in captive animal health before putting microbiome manipulations broadly into practice.

Animals in captive and urban environments encounter evolutionarily novel conditions shaped by humans, such as altered diets, exposure to human-associated bacteria, and, potentially, medical interventions. Captive and urban environments have been demonstrated to affect gut microbial composition and diversity independently but have not yet been studied together. By sequencing the gut microbiota of deer mice living in laboratory, zoo, urban and natural settings, we sought to identify (i) whether captive deer mouse gut microbiota have similar composition regardless of husbandry conditions and (ii) whether captive and urban deer mice have similar gut microbial composition. We found that the gut microbiota of captive deer mice were distinct from those of free-living deer mice, indicating captivity has a consistent effect on the deer mouse microbiota regardless of location, lineage or husbandry conditions for a population. Additionally, the gut microbial composition, diversity and bacterial load of free-living urban mice were distinct from those of all other environment types. Together, these results indicate that gut microbiota associated with captivity and urbanization are likely not a shared response to increased exposure to humans but rather are shaped by environmental features intrinsic to captive and urban conditions.

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Abstract. Resistance to antibiotics is a growing problem that imposes limitations on current therapy around the world. The World Health Organization (WHO) recommends creating new antibacterial molecules to inhibit the most harmful bacteria by aiming at specific targets. Among such bacteria is multi-drug resistant Pseudomonas aeruginosa, a Gram-negative bacterium responsible for 70% of invasive infections worldwide. The aim of this investigation was to synthesize N-arylbenzylimines, examine their antibacterial activity against P. aeruginosa ATCC 27853, and determine their physicochemical properties by quantitative structure-activity relationship (QSAR/SAR) analysis. Seven N-arylbenzylimines were synthesized with yields ≥50%, all with the E-configuration (as shown by NMR spectra and confirmed with X-ray diffraction). The in vitro microbiological evaluations were carried out with the Kirby-Bauer method, following the guidelines of the Clinical & Laboratory Standards Institute (CLSI). The N-arylbenzylimines produced a very good antibacterial effect on P. aeruginosa, with minimum inhibitory concentration (MIC) values ranging ​​from 198.47-790.10 µM, calculated by the Hill method. Based on the slopes of the concentration-response curves, the mechanism of action is different between the test compounds and aztreonam, the reference drug. The QSAR study performed with in vitro experimental data found that biological activity correlates most significantly with molecular size, followed by lipophilicity and electronic effects. According to the SAR analysis of antibacterial activity, molecules cross bacterial barriers differently if they bear substituents with resonance versus inductive electronic effects. The physicochemical data presently described are of utmost importance for designing and developing new molecules to combat the pathogenicity and resistance of P. aeruginosa.   Resumen. La resistencia a los antibióticos es un problema en aumento que impone limitaciones en la terapia actual a nivel mundial. La Organización Mundial de la Salud (OMS) recomienda crear nuevas moléculas antibacterianas para inhibir las bacterias más dañinas por medio de dianas específicas. Pseudomonas aeruginosa, entre estas bacterias, es Gram-negativa, resistente a múltiples fármacos, y responsable del 70% de las infeccione invasivas en el mundo. El objetivo de esta investigación fue sintetizar N-arilbenziliminas, examinar su actividad antibacteriana contra P. aeruginosa ATCC 27853, y determinar sus propiedades fisicoquímicas mediante análisis cuantitativo de relación estructura-actividad (QSAR/SAR). Todos los siete N-arilbenziliminas sintetizados tuvieron rendimientos ≥50% y la configuración E (de acuerdo con la espectroscopía de RMN y la difracción de rayos-X). Las pruebas microbiológicas in vitro se realizaron mediante el método Kirby-Bauer, siguiendo las directrices del Instituto de Estándares Clínicos y de Laboratorio (CLSI). Las N-arilbenziliminas mostraron efecto antibacteriano relevante sobre P. aeruginosa, con valores de la concentración mínima inhibitoria (MIC) en el rango de 198.47-790.10 µM, calculado por el método de Hill. Las pendientes de las curvas de concentración-respuesta sugieren que el mecanismo de acción es distinto entre las N-arilbenziliminas y aztreonam, el fármaco de referencia. El analisis QSAR de los datos experimentales indica que la actividad biológica se correlaciona de manera más significativa con el tamaño molecular, seguida de la lipofilicidad y los efectos electrónicos. Según el análisis SAR de la actividad antibacteriana, las moléculas cruzan las barreras bacterianas en forma diferente si portan sustituyentes con efectos electrónicos inductivos versus de resonancia. Estos datos fisicoquímicos son de suma importancia en el diseño y desarrollo de nuevas moléculas para combatir la infección y resistencia de P. aeruginosa.