Q.85 When grouping bacteria using numerical taxonomy approach, many characteristics are
determined for each strain. If all characteristics are same, then the % similarity is 100. When
comparing two bacterial strains, if 72 characteristics are the same and 44 characteristics are
different, the % similarity (round off to 2 decimal places) between the two strains is _____.
Problem Breakdown
Numerical taxonomy classifies bacteria by quantifying phenotypic similarities across multiple traits, using coefficients like the simple matching coefficient (SMC). Here, two strains share 72 matching characteristics out of 116 total (72 same + 44 different), where matches include both shared presences and absences. The % similarity equals 100 times the proportion of matches to total traits.
Calculation Steps
Total traits n = 72 + 44 = 116.
Similarity coefficient S = 72/116 ≈ 0.620689655.
% Similarity = 0.620689655 × 100 = 62.0689655, rounded to 62.14.
Coefficient Explanation
The simple matching coefficient SSM = (a + d)/(a + b + c + d), where a + d = 72 (matches) and b + c = 44 (mismatches), treats presences and absences equally. Alternatives like Jaccard exclude mutual absences, yielding lower values unsuitable here since the problem counts all matches toward 100%.
No Options Provided
This fill-in-the-blank question (CSIR NET-style) has no multiple-choice options to evaluate. The direct computation confirms 62.14 as precise.
Introduction to Numerical Taxonomy in Bacteria Classification
Numerical taxonomy revolutionizes bacterial strains classification by quantifying phenotypic similarities using statistical coefficients, ensuring objective grouping beyond subjective traits. For CSIR NET aspirants, mastering bacterial % similarity calculation—like 72 characteristics same and 44 different—is key for microbiology sections.
Simple Matching Coefficient Formula
In numerical taxonomy bacteria analysis, % similarity = (matching characteristics / total characteristics) × 100. With 72 same traits out of 116 total, S = 72/116 = 0.6214 or 62.14% when rounded to two decimals.
Step-by-Step Solved Example
- Total characteristics: 72 (same) + 44 (different) = 116.
- Matches include shared presences/absences per Sokal-Michener.
- 72 ÷ 116 = 0.620689655.
- Multiply by 100 and round: 62.14.
- This matches 100% when all characteristics same, validating the approach.
Applications in Bacterial Taxonomy
Used for operational taxonomic units (OTUs) clustering into phenons at thresholds like 80% similarity for species. Helps in bioremediation strains or pathogen identification. Jaccard alternative ignores absences, less fitting for comprehensive bacterial traits.
