@article{mbs:/content/journal/micro/10.1099/00221287-47-3-433, author = "Coleman, G. S.", title = "The Metabolism of Free Amino Acids by Washed Suspensions of the Rumen Ciliate Entodinium caudatum", journal= "Microbiology", year = "1967", volume = "47", number = "3", pages = "433-447", doi = "https://doi.org/10.1099/00221287-47-3-433", url = "https://www.microbiologyresearch.org/content/journal/micro/10.1099/00221287-47-3-433", publisher = "Microbiology Society", issn = "1465-2080", type = "Journal Article", abstract = "SUMMARY Washed suspensions of Entodinium caudatum, grown in vitro, incubated anaerobically in the presence of penicillin and neomycin, incorporated single amino acids into the cell protein without conversion to any other amino acid. The 14C-labelled components of the protozoal ‘pool’ and the medium were also investigated but no extensive catabolism of the amino acids observed. At low external concentrations the amino acids were taken up by an ‘active’ process, but above a critical concentration the amino acids entered the cell by passive diffusion and they have been divided into two groups depending on whether this critical concentration was approximately 0–0001 M or 0–001 M. The rate of amino acid uptake was not altered by the presence of inert particulate matter. Of the 75% of the cell volume occupied by liquid, approximately two-thirds was freely available to amino acids.", }