Flavobacterium baculatum sp. nov., a carotenoid and flexirubin-type pigment producing species isolated from flooded paddy field.

Abstract

A Gram-stain-negative, aerobic, asporogenous, motile by gliding, dull-yellow, long rod-shaped bacterial strain, designated SNL9T, was isolated from a flooded paddy field near Dongguk University, Republic of Korea. The results of phylogenetic analyses based on 16S rRNA gene sequences indicated that SNL9T represents a member of the genus Flavobacterium and is most closely related to Flavobacterium ummariense DS-12T (96.2%) and Flavobacterium viscosum YIM 102796T (96.3%). The average nucleotide identity and in silico DNA-DNA hybridization (DDH) values with F. ummariense DS-12T and F. viscosum YIM 102796T were 89.3/39.1 and 87.1/33\u200a%, respectively. The major fatty acids of SNL9T were identified as iso-C15\u200a:\u200a0, summed feature 3 (comprising C16\u200a\u200a:\u200a\u200a1ω6c and/or C16\u200a\u200a:\u200a\u200a1ω7c) and summed feature 9 (comprising iso-C17\u200a:\u200a1ω9c and/or 10 methyl C16\u200a:\u200a0). SNL9T contained MK-6 as the major respiratory quinone. The polar lipids were phoshatidylethanolamine, one unidentified aminophosphoglycolipid, three unidentified aminoglycolipids, two unidentified glycolipids and one unidentified phosphoglycolipid. The DNA G+C content was 34.2\u2009mol%. SNL9T produces carotenoid and flexirubin-type pigments. Among them, carotenoids are particularly valuable for the biotechnological and pharmaceutical industries due to their antioxidant activity. Aryl polyenes (APE) pigments were also found in SNL9T which are responsible for yellow pigment in bacteria. They are stored in the bacterial membrane and protect the bacteria from oxidative stress, particularly from reactive oxygen species. In this paper, we describe a novel isolate, SNL9T, which protect itself from the attack of free radicals using specific natural products in the membrane. Because of their anti-oxidation properties, aryl polyenes may also be of interest to the cosmetic industry. On the basis of the results of phenotypic, genotypic and chemotaxonomic analyses, SNL9T represents a novel species of the genus Flavobacterium, for which the name Flavobacterium baculatum sp. nov. is proposed. The type is SNL9T (=KACC 21170T=NBRC 113746T).