Changes in lactic acid concentrations in culture media and its implications in the inhibition of fungal development

ABSTRACT In the following research, a novel antifungal culture method was discussed with the aim of developing bacterial culture media in which fungal growth is inhibited and bacterial growth is stimulated. This technique is based on the use of lactic acid as an antifungal agent, due to its capacity to neutralise the electrochemical gradient of fungal cell membranes, thus inhibiting their development. Based on this principle, the Minimum Inhibitory Concentration (MIC) of lactic acid in the culture media was investigated by changing its concentrations. After the preparation of the solutions, microbiological seeding was carried out in the different experimental groups. Data were collected using a quadrat sampling technique for subsequent statistical analysis using the T-test coefficient. As a result, the minimum inhibitory concentration of lactic acid was found to be 20%, where fungal growth was inhibited, and bacterial growth was stimulated. RESUMEN En la presente investigación, se discutió acerca de un novedoso método de cultivo antifúngico con la finalidad de desarrollar medios de cultivo bacterianos; en los que el crecimiento de hongos se viera inhibido y el bacteriano estimulado. Esta técnica se basa en el uso del ácido láctico como agente antifúngico, debido a la capacidad de este ácido para neutralizar el gradiente electroquímico de las membranas celulares de los hongos, inhibiendo así su desarrollo. A partir de esta premisa, se investigó la Concentración Inhibitoria Mínima (CIM) del ácido láctico en los medios de cultivo mediante un cambio en sus concentraciones. Posterior a la preparación de las soluciones, se procedió a la siembra microbiológica en los diferentes grupos experimentales. Los datos fueron recolectados mediante una técnica de muestreo por cuadrantes para su posterior análisis estadístico mediante el coeficiente de la Prueba T. Como resultado, se encontró que la concentración inhibitoria mínima del ácido láctico fue del 20%, donde el desarrollo fúngico se vio inhibido y el bacteriano estimulado. Published Electronically Background and Aims: Lactic acid has been shown to have a negative effect on the chemical activity of fungal cell membranes and is therefore proposed to be used as an antifungal agent in growth media. Methods: In the current study, an 88% lactic acid solution was used to produce agar solutions for culture media to assess the extent to which lactic acid can inhibit fungal growth. Subsequently, a quadrant sampling technique and a statistical study were used to measure the extent to which lactic acid can inhibit the growth of fungi. Key Results An inversely proportional correlation was found where lactic acid inhibited fungal growth. Specifically, the minimum inhibitory concentration of lactic acid was 20% and the results were supported by mathematical correlation and a statistical T-test, where 95% reliability was assumed. Conclusions: These results are consistent with the limited research into the molecular pathways of lactic acid in fungal organisms, which establishes, as in this research, that lactic acid negatively affects fungi and their development in culture media.