Kocur and Martinec conducted a taxonomic study of six Sarcina aurantiaca strains obtained from various international collections to clarify its classification within the genus Sarcina. Previous taxonomic literature distinguished S. aurantiaca from S. lutea subsp. flava and S. lutea subsp. lutea primarily by orange pigment production. The researchers characterized the strains morphologically, culturally, and biochemically using established methods. All strains were Gram-positive cocci forming characteristic cell packets, 1.2-2 micrometers in diameter, with nearly identical cultural characteristics on various media. Biochemical tests revealed only minor variations among strains, consistent with published data. The authors found that S. aurantiaca and S. lutea subsp. flava were essentially identical except for pigment production. Since pigment production in these bacteria is variable and influenced by multiple factors, they concluded that maintaining S. aurantiaca as a separate species was unjustified. The authors proposed that S. aurantiaca be regarded as a synonym of S. lutea subsp. flava, citing precedent from other researchers demonstrating pigment variability in related species.

Key findings

• Six strains of Sarcina aurantiaca were morphologically and biochemically nearly identical to Sarcina lutea subsp. flava
• The primary distinguishing feature, orange pigment production, proved variable and unreliable, with one strain producing no pigment on potato medium
• Minor biochemical differences observed among strains were inconsistent and typical of natural variation in Sarcina lutea subspecies
• Pigment variability is a common phenomenon in pigment-producing bacteria, not a reliable taxonomic character
• The authors proposed that Sarcina aurantiaca should be considered a synonym of Sarcina lutea subsp. flava rather than a separate species