Biochemical Test of Bacteroides fragilis

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Biochemical Test of Bacteroides fragilis

Basic Characteristics Properties (Bacteroides fragilis)
Capsule Positive (+ve)
Catalase Positive (+ve)
Flagella Negative (-ve)
Gelatin Hydrolysis Weakly Positive (+ve)
Gram Staining Gram-negative (-ve)
Growth in Bile (20%) Positive (+ve)
Hemolysis Negative (-ve)
Indole Variable
Motility Negative (-ve)
Nitrate Reduction Negative (-ve)
Oxidase Variable
Pigment Negative (-ve)
Shape Rod-shaped cells with rounded ends.
Spore Negative (-ve)
Thioglycolate with bile Positive (+ve)
Urease Negative (-ve)

Fermentation of
Arabinose Negative (-ve)
Cellobiose Variable
Glucose Positive(+ve)
Glycogen Positive(+ve)
Inositol Negative (-ve)
Lactose Positive(+ve)
Maltose Positive(+ve)
Mannitol Negative (-ve)
Mannose Positive(+ve)
Melibiose Weakly Positive (+ve)
Raffinose Positive(+ve)
Rhamnose Negative (-ve)
Ribose Negative (-ve)
Salicin Negative (-ve)
Starch Positive (+ve)
Sucrose Positive (+ve)
Trehalose Negative (-ve)
Xylan Negative (-ve)
Xylose Positive (+ve)

Enzymatic Reactions
Alanine arylamidase Positive (+ve)
Esculin Hydrolysis Positive (+ve)
Glutamic acid decarboxylase Positive (+ve)
Glycine arylamidase Negative (-ve)
Leucine arylamidase Positive (+ve)
Leucyl glycine arylamidase Positive (+ve)
N-Acety1- b-glucosaminidase Positive (+ve)
ONPG (β-galactosidase) Positive (+ve)

References

  1. Editors: Krieg, N.R., Ludwig, W., Whitman, W., Hedlund, B.P., Paster, B.J., Staley, J.T., Ward, N., Brown, D., Parte, A. (2010). Bergey’s Manual of Systematic Bacteriology. Volume 4: The Bacteroidetes, Spirochaetes, Tenericutes (Mollicutes), Acidobacteria, Fibrobacteres, Fusobacteria, Dictyoglomi, Gemmatimonadetes, Lentisphaerae, Verrucomicrobia, Chlamydiae, and Planctomycetes.
  2. http://www.onlinebiologynotes.com/bacteroides-general-characteristics-classification-pathogenesis-clinical-manifestations-lab-diagnosis-biochemical-testscharacteristicsculture-characteristics-treatment/
  3. https://www.microbiologyresearch.org/docserver/fulltext/jmm/13/1/medmicro-1369.pdf
  4. http://www.vetbact.org/?artid=102
  5. https://www.sciencedirect.com/topics/immunology-and microbiology/bacteroides-fragilis
  6. Draper, D. L., & Barry, A. L. (1977). Rapid identification of Bacteroides fragilis with bile and antibiotic disks. Journal of clinical microbiology, 5(4), 439-43.
  7. https://watermark.silverchair.com/23-Supplement_1-S66.pdf
  8. https://catalog.hardydiagnostics.com/cp_prod/Content/hugo/Bacteriodes.htm

About Author

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Sagar Aryal, PhD

Dr. Sagar Aryal is a microbiologist, researcher, and science communicator from Nepal. He is also co-founder and Research Head of the Department of Natural Products at the Kathmandu Research Institute for Biological Sciences (KRIBS), where he leads research on natural product discovery and microbial biodiversity. Dr. Aryal earned his Ph.D. in Microbiology from Tribhuvan University, Kathmandu, Nepal, in 2025, supported by a DAAD Research Grant and a University Grants Commission (UGC) Nepal Ph.D. Fellowship. His research interests include Actinomycetes, Myxobacteria, microbial taxonomy, and natural products, particularly the discovery of bioactive compounds with potential pharmaceutical applications. He isolated and identified Nocardia nepalensis, a novel bacterial species from Nepal, contributing to understanding microbial diversity in the region. Dr. Aryal has published more than 16 research articles in international journals and contributed three book chapters to established academic publications. He has presented scientific research findings and developed international research collaborations through visits to more than 18 countries across Asia, Europe, North America, and Oceania. From 2023 to 2025, he served as the American Society for Microbiology (ASM) Young Ambassador to Nepal. Since December 2025, he has served as an Editorial Board Member of Scientific Reports, a Nature Portfolio journal. In recognition of his scientific contributions, Dr. Aryal received the NAST Science and Technology Youth Award 2025 from the Nepal Academy of Science and Technology. He previously received the Frs. Locke and Stiller Research Award (LSRA) for the 2017-2018 cycle from St. Xavier's College, Kathmandu, and a Nepal Academy of Science and Technology (NAST) Research Grant for 2017-2018. Alongside his scientific career, Dr. Aryal has more than 15 years of experience in blogging, content writing, and search engine optimization (SEO).