This study identifies Flavobacterium pectinovorum Dorey 1959, a pectolytic bacterium originally isolated from soil, as a synonym of Cytophaga johnsonae Stanier 1947. The holotypic strain F. pectinovorum NCIB 9059 was extensively compared with nine C. johnsonae cultures through comprehensive morphological, physiological, biochemical, and antimicrobial lytic analyses. Both organisms share essential characteristics: orange-yellow pigmentation, gram-negative aflagellate rods with gliding motility, identical cell dimensions, similar colony morphology on multiple agar types, and comparable growth requirements. Physiologically and biochemically, the organisms match in salt tolerance, pH range, temperature limits, nitrogen source utilization, antibiotic sensitivities, and enzyme production including pectolytic activity. DNA base composition confirmed the relationship, with F. pectinovorum showing 32.7 mol% G+C content within the 30-35 mol% range reported for C. johnsonae. Lytic spectrum against bacteria, fungi, and other organisms was consistent between strains. The study supports the consensus that F. pectinovorum should be reclassified from Flavobacterium to Cytophaga, establishing formal synonymy with C. johnsonae.

Key findings

• F. pectinovorum NCIB 9059 matches C. johnsonae in morphology, colony characteristics, and cell dimensions across multiple growth media
• Both organisms share identical physiological properties including salt tolerance, pH range (5-10), temperature range (0-35°C), and nitrogen source utilization patterns
• DNA G+C content of F. pectinovorum (32.7 mol%) falls within the reported C. johnsonae range of 30-35 mol%
• Biochemical profiles including enzyme activities, antimicrobial lytic spectra, and antibiotic sensitivities are consistent across both organisms and multiple C. johnsonae strains