Ensiling is one of the best known method to preserve fodder. The forage before ensiling intended for silages usually contains a low number of lactic acid bacteria (LAB), so it is necessary to apply starter cultures of selected strains. Traditionally, LAB starter cultures were applied to lower the pH by producing lactic acid and to inhibit the growth of undesirable epiphytic microorganisms by competing for nutrients. Nowadays, LAB inoculants have become an effective tool for creating microbial quality of silages by selecting species with extraordinary features. Epiphytic microflora characteristic of plant material used for the production of silages and the sources of undesirable microflora in the ensiling process are discussed. This review focuses on the most frequently studied issues related to the microbial silage quality and the recent trends in increasing the quality by LAB inoculants, with respect to recent directions for selecting types of modern LAB for inoculation. Among them, the main trends described were prevention of the growth of filamentous fungi and detoxification of mycotoxins by LAB inoculants, inhibition of yeast growth by LAB present in preparations and limiting the development of pathogenic bacterial microflora through controlled fermentation with the participation of LAB and the presence of their metabolites.

No abstract

No abstract

There is a significant range of bacterial inoculants for forage ensiling, but there is still a need for formulations to improve the safety of feed. The objective of the study was to evaluate the usefulness of three lactobacilli strains in alfalfa (Medicago sativa L.) The following bacterial inoculants were used: Lactocacillus plantarum K KKP 593p (LPK), L. plantarum C KKP 788p (LPC), L. buchneri KKP 907p (LB), and mix of all three strains (LPK+LPC+LB). The application of bacterial inoculants in alfalfa ensiling resulted in a reduction of the total number of molds, Clostridium perfringens and Listeria sp. (up to 5, 7, and 5 times respectively for LB inoculant in comparison to untreated silage). Total inhibition of Salmonella sp. and Escherichia coli growth was achieved in silages treated with all inoculants except for LPC. Aerobic stability in the control silage was the lowest (77 h) and doubled under the influence of bacterial inoculants. The most stable according to aerobic stability was silage treated with LB inoculant (175 h), where the highest concentrations of acetic acid (4.8 g kg -1 ), propionic acid (0.7 g kg -1 ) and 1,2-propanediol (526 mg kg -1 ) were reported. The study discussed that it is important to evaluate not only the effect of bacterial inoculants on physicochemical and microbiological silage properties, as the presence and expression of antibiotic resistance genes in lactic acid bacteria have been reported. The results of antimicrobial susceptibility testing of the strains showed that almost all minimum inhibitory concentrations values for eight antibiotics were equal to or below the corresponding breakpoints proposed by the European Food Safety Authority, Additives and Products or Substances used in Animal Feed Panel.

Yarrowia lipolytica is one of the most studied “non-conventional” yeast species capable of synthesizing a wide group of valuable metabolites, in particular lipases and other hydrolytic enzymes, microbial oil, citric acid, erythritol and γ-decalactone. Processes based on the yeast have GRAS status (“generally recognized as safe”) given by Food and Drug Administration. The majority of research communications regarding to Y. lipolytica claim that the yeast species is non-pathogenic. In spite of that, Y. lipolytica, like other fungal species, can cause infections in immunocompromised and critically ill patients. The yeast possess features that facilitate invasion of the host cell (particularly production of hydrolytic enzymes), as well as the protection of the own cells, such as biofilm formation. The aim of this study was to present well-known yeast species Y. lipolytica as a rare opportunistic fungal pathogen. Possible pathogenicity and epidemiology of this yeast species were discussed. Antifungal drugs susceptibility and increasing resistance to azoles in Y. lipolytica yeasts were also presented.Electronic supplementary materialThe online version of this article (10.1007/s11274-018-2583-8) contains supplementary material, which is available to authorized users.