List of contributors.- Preface .- 1 An overview of antimicrobial properties of different classes of phytochemicals.- 2 Antimicrobial properties of flavonoids.- 3 Antiviral properties of Phytochemicals.- 4 Antimicrobial properties of organosulfur compounds.- 5 Antimicrobial activities of essential oils.- 6 Phytochemicals against drug-resistant microbes.- 7 Phytochemicals as anti-microbial food preservatives.- 8 Dietary tannins on microbial ecology of the gastrointestinal tract in ruminants.- 9 Manipulating ruminal biohydrogenation by the use of plants bioactive compounds.- 10 Essentials oils and rumen microbial populations.- 11 Saponins: effects on rumen microbial ecosystem and metabolism in the rumen.- 12 Effect of plant secondary metabolites on rumen methanogens and methane emissions by ruminants.- 13 Phytochemicals and gut microbial populations in non-ruminants.- Index.