Diversidade de fungos em silagens de milho inoculadas com Lactobacillus buchneri (CCMA1366) ou Lactobacillus farraginis (CCMA1362)

Abstract

Corn (Zea mays L.) is one of the most used forage for silage production, but it is susceptible to aerobic deterioration by undesirable microorganisms, such as fungi. The present study aimed to quantify and identify fungi present in corn plant and in silages inoculated with Lactobacillus buchneri (CCMA 1366) or Lactobacillus farraginis (CCMA 1362). Three treatments were used: I) Control (CON): Corn silage without inoculation; II) Corn silage inoculated with L. buchneri; III) Corn silage inoculated with L. farraginis. The silages were stored for 29, 103 and 193 days and analyzed for fungal microbial populations, dry matter, pH, water activity (a w ) and fermentation products (ethanol, 1,2-propanediol and acetic, propionic, butyric acids). For data analysis, the fat2.dic function of the ExpDes.pt package of the statistical program R was used. Two contrasts were tested to compare: I) CON vs. L. buchneri, II) CON vs. L. farraginis. Significance was declared with P <0.05. Descriptive analysis charts were made for the microbial counts using the ggplot2 package of the statistical program R. All silages presented adequate pH, with lower values in the control silage. The inoculated silages had a higher concentration of acetic acid and 1,2 - propanediol compared to the control, indicating the effective establishment of the strains. Five yeast species were found in the fresh plant. Candida glabrata was isolated from the control silage and silage inoculated with L. buchneri. No growth of yeasts ocourred in the silages inoculated with L. farraginis. The highest count of filamentous fungi was observed in time 103 days where Aspergillus fumigatus was predominant. Species of the genus Fusarium, Phoma, Beauveria were isolated from fresh forrage. The genus Monascus and the species Aspergillus flavus were isolated from 29 and 103 days, respectively. This work showed the dynamics of the fungal population and the fermentation of the inoculated silages, which contributes to the creation of strategies to increase aerobic stability, a major challenge in corn silage.