Summary auto-generated
Researchers isolated 37 bacterial strains from fruit and soil samples in Japan that produce 2,5-diketo-D-gluconic acid from D-glucose. These gram-negative, facultatively anaerobic strains were phenotypically related to the genus Pantoea and grouped into three distinct phenotypic categories. DNA-DNA hybridization studies using the S1 nuclease method revealed that the three groups showed low DNA relatedness to each other (28-46%) and to existing Pantoea species (less than 18% relatedness), establishing them as genetically distinct. Based on phenotypic characteristics, DNA base composition, and DNA hybridization data, the researchers propose three new Pantoea species: P. citrea (5 strains), P. punctata (7 strains), and P. terrea (25 strains). These organisms are distinguished by motility patterns, growth temperatures, and biochemical characteristics. Type strains were deposited in the American Type Culture Collection under ATCC numbers 31623T, 31626T, and 31628T, respectively. The three species differ from previously described Pantoea species in G+C content (49.7-51.9 mol% versus 55.6-57.8 mol%) and possess characteristic 2-keto-D-gluconate dehydrogenase activity, a trait rare among Enterobacteriaceae.
Key findings
- Three new Pantoea species were identified from soil and fruit samples, distinguished by DNA-DNA hybridization showing 28-46% relatedness between groups and <18% to known Pantoea species
- P. terrea strains were motile with lateral flagella while P. citrea and P. punctata were nonmotile, providing clear phenotypic differentiation
- All isolates possessed 2-keto-D-gluconate dehydrogenase activity and produced 2,5-diketo-D-gluconic acid from D-glucose, distinguishing them from most other Enterobacteriaceae
- G+C content of the three new species (49.7-51.9 mol%) was significantly lower than established Pantoea species (55.6-57.8 mol%)
- Type strains were successfully deposited in the ATCC and assigned catalog numbers ATCC 31623T, 31626T, and 31628T for P. citrea, P. punctata, and P. terrea respectively
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Abstract
A total of 37 bacterial strains with the general characteristics of the family Enterobacteriaceae were isolated from fruit and soil samples in Japan as producers of 2,5-diketo-D-gluconic acid from D-glucose. These organisms were phenotypically most closely related to the genus Pantoea (F. Gavini, J. Mergaert, A. Beji, C. Mielearek, D. Izard, K. Kersters, and J. De Ley, Int. J. Syst. Bacteriol. 39:337-345, 1989) and were divided into three phenotypic groups. We selected nine representative strains from the three groups for an examination of DNA relatedness, as determined by the S1 nuclease method at 60°C. Strain SHS 2003T (T = type strain) exhibited 30 to 41 and 28 to 33% DNA relatedness to the strains belonging to the strain SHS 2006T group (strains SHS 2004, SHS 2005, SHS 2006T, and SHS 2007) and to the strains belonging to the strain SHS 2008T group (strains SHS 2008T, SHS 2009, SHS 2010, and SHS 2011), respectively. Strain SHS 2006T exhibited 38 to 46% DNA relatedness to the strains belonging to the strain SHS 2008T group. The levels of DNA relatedness within the strain SHS 2006T group and within the strain SHS 2008T group were more than 85 and 71%, respectively. Strain SHS 2003T, SHS 2006T, and SHS 2008T DNAs exhibited less than 18% binding to Pantoea dispersa ATCC 14589T and Pantoea agglomerans ATCC 27155T DNAs. On the basis of phenotypic characteristics, DNA base compositions, and the results of DNA relatedness studies, the nine strains which we studied were considered to be new species of the genus Pantoea, and the names Pantoea citrea, Pantoea punctata, and Pantoea terrea are proposed for strains belonging to the strain SHS 2003T, SHS 2006T, and SHS 2008T groups, respectively. P. citrea SHS 2003T, P. punctata SHS 2006T, and P. terrea SHS 2008T have been deposited in the American Type Culture Collection as strains ATCC 31623T ("Erwinia citreus"), ATCC 31626T ("Erwinia punctata"), and ATCC 31628T ("Erwinia terreus"), respectively.