scholarly journals Litoribacterium kuwaitense gen. nov., sp. nov., isolated from a Kuwait tidal flat

2021 ◽  
Vol 71 (4) ◽  
Author(s):  
Huda Mahmoud ◽  
Susan Eapen ◽  
Fatimah Al-Bajjali ◽  
Anwar Al-Qattan ◽  
Liny Jose
Keyword(s):  
Tidal Flat ◽  
Diaminopimelic Acid ◽  
16S Rrna Genes ◽  
Rrna Genes ◽  
Strictly Aerobic ◽  
Phenotypic Properties ◽  
Unidentified Phospholipid ◽  
Novel Genus ◽  
A Genome ◽  
Encoding Genes

A Gram-stain-positive, strictly aerobic, spore-forming, rod-shaped and non-motile bacterium designated strain SIJ1T was obtained from tidal flat sediment collected from the northern shore of Kuwait Bay, northwest of the Arabian Gulf. Strain SIJ1T grew optimally at 30 °C and pH 7–8 in the presence of 6 % (w/v) NaCl. The cell-wall peptidoglycan was based on meso-diaminopimelic acid and an unsaturated menaquinone with seven isoprene units (MK-7) was the predominant respiratory quinone. It contained anteiso-C15 : 0, iso-C16 : 0 and iso-C15 : 0 as the major fatty acids and ribose as the major whole-cell sugar. The polar lipids were diphosphatidylglycerol, phosphatidylglycerol, unidentified phospholipid, an unidentified glycolipid, phosphoglycolipid and an unidentified lipid. Phylogenetic analysis based on 16S rRNA genes revealed that SIJ1T showed a distinct evolutionary lineage within the Firmicutes. The DNA G+C content was 43.1 mol% and the full genome analysis for strain SIJ1T showed that it had a genome size of 3 989 945 bp and contained 4085 predicted protein-encoding genes. The SIJ1T annotated genome showed more stress resistance encoding genes in comparison to its closely related strains. The amino acid identity and average nucleotide identity data for the whole genome proved that strain SIJ1T does indeed represent a novel genus. The strain was distinguishable from the phylogenetically related genera through differences in several phenotypic properties. On the basis of the phenotypic, phylogenetic and genetic data, strain SIJ1T represents a novel genus and species in the family Bacillaceae, for which the name Litoribacterium kuwaitense gen. nov., sp. nov. is proposed. The type strain is SIJ1T (=DSM 28862T=LMG 28316T).

scholarly journals Ecofriendly Synthesis of Silver Nanoparticles by Terrabacter humi sp. nov. and Their Antibacterial Application against Antibiotic-Resistant Pathogens

2020 ◽  
Vol 21 (24) ◽  
pp. 9746
Author(s):  
Shahina Akter ◽  
Sun-Young Lee ◽  
Muhammad Zubair Siddiqi ◽  
Sri Renukadevi Balusamy ◽  
Md. Ashrafudoulla ◽  
...  
Keyword(s):  
Silver Nanoparticles ◽  
Spherical Shape ◽  
Optimal Growth ◽  
Rrna Genes ◽  
Rrna Gene ◽  
Strictly Aerobic ◽  
Drug Resistant ◽  
Protein Coding ◽  
A Genome ◽  
The Fourier Transform

It is essential to develop and discover alternative eco-friendly antibacterial agents due to the emergence of multi-drug-resistant microorganisms. In this study, we isolated and characterized a novel bacterium named Terrabacter humi MAHUQ-38T, utilized for the eco-friendly synthesis of silver nanoparticles (AgNPs) and the synthesized AgNPs were used to control multi-drug-resistant microorganisms. The novel strain was Gram stain positive, strictly aerobic, milky white colored, rod shaped and non-motile. The optimal growth temperature, pH and NaCl concentration were 30 °C, 6.5 and 0%, respectively. Based on 16S rRNA gene sequence, strain MAHUQ-38T belongs to the genus Terrabacter and is most closely related to several Terrabacter type strains (98.2%–98.8%). Terrabacter humi MAHUQ-38T had a genome of 5,156,829 bp long (19 contigs) with 4555 protein-coding genes, 48 tRNA and 5 rRNA genes. The culture supernatant of strain MAHUQ-38T was used for the eco-friendly and facile synthesis of AgNPs. The transmission electron microscopy (TEM) image showed the spherical shape of AgNPs with a size of 6 to 24 nm, and the Fourier transform infrared (FTIR) analysis revealed the functional groups responsible for the synthesis of AgNPs. The synthesized AgNPs exhibited strong anti-bacterial activity against multi-drug-resistant pathogens, Escherichia coli and Pseudomonas aeruginosa. Minimal inhibitory/bactericidal concentrations against E. coli and P. aeruginosa were 6.25/50 and 12.5/50 μg/mL, respectively. The AgNPs altered the cell morphology and damaged the cell membrane of pathogens. This study encourages the use of Terrabacter humi for the ecofriendly synthesis of AgNPs to control multi-drug-resistant microorganisms.

Thalassobacter stenotrophicus Macián et al. 2005 is a later synonym of Jannaschia cystaugens Adachi et al. 2004, with emended description of the genus Thalassobacter

2005 ◽  
Vol 55 (5) ◽  
pp. 1959-1963 ◽  
Author(s):  
M. J. Pujalte ◽  
M. C. Macián ◽  
D. R. Arahal ◽  
E. Garay
Keyword(s):  
16S Rrna ◽  
Genomic Dna ◽  
Sequence Similarity ◽  
16S Rrna Genes ◽  
Rrna Genes ◽  
Phenotypic Traits ◽  
Rrna Gene ◽  
Phenotypic Properties ◽  
Sequence Comparisons ◽  
Emended Description

The type strains of Jannaschia cystaugens (LMG 22015T) and Thalassobacter stenotrophicus (CECT 5294T) were analysed by means of genomic DNA–DNA hybridization, comparison of 16S rRNA gene sequences and phenotypic properties determined under the same methodological conditions. J. cystaugens LMG 22015T showed DNA–DNA relatedness levels of 72 % when hybridized with the genomic DNA of T. stenotrophicus CECT 5294T. Sequence comparisons revealed that the 16S rRNA genes of the two strains had a similarity of 99·8 %. The cellular fatty acid and polar lipid compositions of the two strains and their DNA mol% G+C contents were almost identical. Bacteriochlorophyll a (Bchl a) and polyhydroxybutyrate were produced by both strains under the same culture conditions. Their closest phylogenetic neighbours were Jannaschia helgolandensis and Jannaschia rubra; however, the low sequence similarity values (95·7–95·9 %) and several important differences in phenotypic traits (ionic requirements, Bchl a production and polar lipids) support the distinction between the genera Thalassobacter and Jannaschia. Thus, we propose the unification of J. cystaugens (LMG 22015T) and T. stenotrophicus (CECT 5294T) as Thalassobacter stenotrophicus (type strain, CECT 5294T=DSM 16310T). An emended description of the genus Thalassobacter is also presented.

scholarly journals Mucilaginibacter koreensis sp. nov., isolated from leaf mould

2014 ◽  
Vol 64 (Pt_7) ◽  
pp. 2274-2279 ◽  
Author(s):  
Cheol Su Park ◽  
Kyudong Han ◽  
Tae-Young Ahn
Keyword(s):  
16S Rrna ◽  
Type Species ◽  
Sequence Similarity ◽  
Optimal Growth ◽  
16S Rrna Genes ◽  
Rrna Genes ◽  
Rrna Gene ◽  
Strictly Aerobic ◽  
Content Type ◽  
Link Type

A Gram-staining-negative, strictly aerobic, rod-shaped, pale-pink pigmented bacterial strain, designated TF8T, was isolated from leaf mould in Cheonan, Republic of Korea. Its taxonomic position was determined through a polyphasic approach. Optimal growth occurred on R2A agar without NaCl supplementation, at 25–28 °C and at pH 6.0–7.0. Phylogenetic analysis based on 16S rRNA gene sequences showed that strain TF8T belongs to the genus Mucilaginibacter in the family Sphingobacteriaceae . The sequence similarity between 16S rRNA genes of strain TF8T and the type strains of other species of the genus Mucilaginibacter ranged from 92.1 to 94.7 %. The closest relatives of strain TF8T were Mucilaginibacter lutimaris BR-3T (94.7 %), M. soli R9-65T (94.5 %), M. litoreus BR-18T (94.5 %), M. rigui WPCB133T (94.0 %) and M. daejeonensis Jip 10T (93.8 %). The major isoprenoid quinone was MK-7 and the major cellular fatty acids were iso-C15 : 0 (33.0 %), summed feature 3 (C16 : 1ω7c and/or C16 : 1ω6c; 24.8 %) and summed feature 8 (C18 : 1ω7c and/or C18 : 1ω6c; 13.0 %). The major polar lipids of TF8T were phosphatidylethanolamine and three unidentified aminophospholipids. The G+C content of the genomic DNA was 46.2 mol%. On the basis of the data presented here, strain TF8T is considered to represent a novel species of the genus Mucilaginibacter , for which the name Mucilaginibacter koreensis sp. nov. is proposed. The type strain is TF8T ( = KACC 17468T = JCM 19323T).

Maribacter chungangensis sp. nov., isolated from a green seaweed, and emended descriptions of the genus Maribacter and Maribacter arcticus

2013 ◽  
Vol 63 (Pt_7) ◽  
pp. 2553-2558 ◽  
Author(s):  
Veeraya Weerawongwiwat ◽  
Hyeonji Kang ◽  
Min Young Jung ◽  
Wonyong Kim
Keyword(s):  
Type Species ◽  
Diaminopimelic Acid ◽  
Rrna Gene ◽  
Strictly Aerobic ◽  
Phenotypic Data ◽  
Unidentified Phospholipid ◽  
Content Type ◽  
Link Type ◽  
Green Seaweed ◽  
Distinct Lineage

A Gram-stain-negative, non-spore-forming, strictly aerobic, orange-pigmented bacterial strain, motile by gliding, designated CAU 1044T, was isolated from a green seaweed and its taxonomic position was investigated using a polyphasic approach. Phylogenetic analysis based on 16S rRNA gene sequences revealed that strain CAU 1044T formed a distinct lineage within the genus Maribacter and was most closely related to Maribacter antarcticus JCM 15445T and Maribacter arcticus KOPRI 20941T (96.3 and 95.7 % similarity, respectively). Strain CAU 1044T contained menaquinone 6 as the only isoprenoid quinone and iso-C15 : 0, summed feature 3 (comprising C16 : 1ω7c and/or C16 : 1ω6c and/or iso-C15 : 0 2-OH), iso-C17 : 0 3-OH and iso-C15 : 1 G as the major fatty acids. The cell wall peptidoglycan of strain CAU 1044T contained meso-diaminopimelic acid and the major whole-cell sugars were glucose and ribose. The polar lipids were composed of phosphatidylethanolamine, one unidentified phospholipid, six unidentified aminolipids and four unidentified lipids. The DNA G+C content was 40.2 mol%. On the basis of phenotypic data and phylogenetic inference, strain CAU 1044T should be classified as a representative of a novel species in the genus Maribacter for which the name Maribacter chungangensis sp. nov. is proposed. The type strain is CAU 1044T ( = KCTC 23735T  = CCUG 61948T). Emended descriptions of the genus Maribacter and the species M. arcticus KCTC 22053T are also proposed.

scholarly journals Polyphase Taxonomy of Antarctic Bacteria

2021 ◽  
Vol 83 (3) ◽  
pp. 3-13
Author(s):  
G.V. Gladka ◽  
◽  
N.V. Borzova ◽  
O.V. Gudzenko ◽  
V.M. Hovorukha ◽  
...  
Keyword(s):  
16S Rrna ◽  
Related Species ◽  
Nucleotide Sequences ◽  
16S Rrna Genes ◽  
Rrna Genes ◽  
Phenotypic Properties ◽  
Bootstrap Analysis ◽  
Closely Related Species ◽  
Microbiological Methods ◽  
The Antarctic

The phylogenetic structure of bacteria is not always consistent with the traditional classification scheme based on the phenotypic properties of bacteria. That is one of the problems of modern bacterial taxonomy. In addition, traditional methods to identify bacteria using phenotypic properties have a number of disadvantages. In recent decades, significant progress was achieved in the investigation of microbial world using molecular methods for fast identification. The aim of the study was to clarify the species status of four strains of bacteria isolated from black lichens of the cliffs of Galindez Island in the Antarctic on the basis of phenotypic and genetic analysis. Methods. Morphological and cultural properties of bacteria were studied according to generally accepted microbiological methods. Physiological and biochemical ones were investigated using test systems API Coryne and API 20E (bioMerieux SA, France), according to the manufacturer’s instructions. Phylogenetic analysis was performed based on the nucleotide sequences of the 16S rRNA gene. To identify closely related species, a comparative analysis of the nucleotide sequences of 16S rRNA genes was performed using the BLAST software package. The phylogenetic position was determined by constructing trees (dendrograms) to show the position of the studied strains among closely related and typical species (programs ClustalX 2.1, Mega 6.06). The tree was constructed applying ClustalX 2.1 by comparing the nearest neighbors with bootstrap analysis (bootstrap NJ tree) using 1000 bootstrap tests (1000 alternative trees). Then the phylogenetic tree was edited by the program Mega v. 6.00. Results. Based on the results of comparative, phylogenetic and phenotypic analysis, the studied Antarctic strains 180n1, 181n2, 188n2, 190n2 were identified as Pseudomonas fluorescens, Microbacterium foliorum, Sporosarcina aquimarina and Rothia sp., respectively. The coefficient of similarity of 16S rRNA genes of strain 180n1 with such a closely related species from the database P. fluorescens NBRC 14160 was 99.5%; 181n2 with M. foliorum P 333/02 – 99.4%; 188n2 with S. aquimarina SW28 – 99.7%. These strains form common clusters with closely related species on phylogenetic dendrograms. The strain 190n2 can be considered as Rothia sp., since has the remote position from closely related strains in the cluster Rothia and a low percentage of similarity (97.3%) with the species Rothia endophytica YIM 67072. These strains belong to the phyla: Firmicutes, Actinobacteria, Proteobacteria. Conclusions. Phylogenetic and phenotypic analyzes allowed determining the taxonomic position of isolated aerobic chemoorganotrophic microbial strains of the Antarctic. Nucleotide sequences of 16S rRNA genes are deposited in the International GenBank database under numbers HG518622, HG518623, HG518625, HG518626.

Microbacterium paulum sp. nov., isolated from microfiltered milk

2021 ◽  
Vol 71 (11) ◽  
Author(s):  
Paolo Bellassi ◽  
Alessandra Fontana ◽  
Maria Luisa Callegari ◽  
Fabrizio Cappa ◽  
Lorenzo Morelli
Keyword(s):  
Cell Wall ◽  
16S Rrna ◽  
Phylogenetic Tree ◽  
Type Species ◽  
16S Rrna Genes ◽  
Rrna Genes ◽  
Strictly Aerobic ◽  
Species Definition ◽  
Content Type ◽  
Link Type

A novel Gram-stain-positive, strictly aerobic, short rod-shaped bacterium, designated 2CT, was isolated from freshly packaged microfiltered milk. This strain was able to grow within the NaCl concentration range of 0–5 % (w/v), temperature range of 8–37 °C (optimally at 30 °C) and at pH 6.0–10.0. Phylogenetic analysis based on 16S rRNA gene sequences revealed that strain 2CT was closely related to species of the genus Microbacterium , with the highest sequence similarity (99.2 %) to Microbacterium lacticum DSM 20427T as well as Microbacterium flavum DSM 18909T (=YM18-098T). The phylogenetic tree based on 16S rRNA genes showed that strain 2CT clustered with M. flavum DSM 18909T. However, the phylogenetic tree based on concatenated 16S rRNA and four housekeeping genes showed that strain 2CT clustered with M. lacticum DSM 20427T. Furthermore, the phylogenomic tree showed that strain 2CT clustered with M. lacticum DSM 20427T and M. flavum DSM 18909T. The major respiratory quinones were MK-10, MK-11 and MK-12. The predominant cellular fatty acids were anteiso-C15 : 0, iso-C16 : 0 and anteiso-C17 : 0. The polar lipid composition of strain 2CT consisted of diphosphatidylglycerol, phosphatidylglycerol, three unidentified glycolipids and two unidentified lipids. The cell-wall peptidoglycan type was a variant of B1α {Gly} [l-Lys] d-Glu-l-Lys, with the amino acids lysine, glycine, alanine and glutamic acid. The whole-cell sugars consisted of galactose, glucose, ribose and minor amounts of rhamnose. In addition, strain 2CT showed a glycolyl-type cell wall. The genomic DNA G+C content was 69.8mol%, while the average nucleotide identity (ANI) and digital DNA-DNA hybridization (dDDH) values with the closely related Microbacterium species were below the recognized thresholds of 95–96 % ANI and 70 % DDH for species definition. Based on the phenotypic and genotypic data, strain 2CT (=LMG 32277T=CECT 30329T) is considered to represent a new species, for which the name Microbacterium paulum sp. nov. is proposed.

Curvivirga aplysinae gen. nov., sp. nov., a marine bacterium isolated from the sea sponge Aplysina fistularis

2021 ◽  
Vol 71 (7) ◽  
Author(s):  
Stacey R. Goldberg ◽  
Brad A. Haltli ◽  
Hebelin Correa ◽  
Russell G. Kerr
Keyword(s):  
16S Rrna ◽  
Type Species ◽  
16S Rrna Genes ◽  
Rrna Genes ◽  
Rrna Gene ◽  
Strictly Aerobic ◽  
Content Type ◽  
San Salvador ◽  
Link Type ◽  
Aplysina Fistularis

A Gram-stain-negative, strictly aerobic, motile bacterium, designated strain RKSG073T, was isolated from the sea sponge Aplysina fistularis, collected off the west coast of San Salvador, The Bahamas. Cells were curved-to-spiral rods with single, bipolar (amphitrichous) flagella, oxidase- and catalase-positive, non-nitrate-reducing and required salt for growth. RKSG073T grew optimally at 30–37 °C, pH 6–7, and with 2–3 % (w/v) NaCl. The predominant fatty acids of RKSG073T were summed feature 8 (C18 : 1ω6c and/or C18 : 1ω7c) and C16 : 0. Major isoprenoid quinones were identified as Q-10 and Q-9. Phylogenetic analyses of nearly complete 16S rRNA genes and genome sequences positioned strain RKSG073T in a clade with its closest relative Aestuariispira insulae AH-MY2T (92.1 % 16S rRNA gene sequence similarity), which subsequently clustered with Hwanghaeella grinnelliae Gri0909T, Marivibrio halodurans ZC80T and type species of the genera Kiloniella , Thalassospira and Terasakiella . The DNA G+C content calculated from the genome of RKSG073T was 42.2 mol%. On the basis of phylogenetic distinctiveness and polyphasic analysis, here we propose that RKSG073T (culture deposit numbers: ATCC collection = TSD-74T, BCCM collection = LMG 29869T) represents the type strain of a novel genus and species within the family Kiloniellaceae , order Rhodospirillales and class Alphaproteobacteria , for which the name Curvivirga aplysinae gen. nov., sp. nov. is proposed.

scholarly journals Aceticlastic and NaCl-Requiring Methanogen “Methanosaeta pelagica” sp. nov., Isolated from Marine Tidal Flat Sediment

2012 ◽  
Vol 78 (9) ◽  
pp. 3416-3423 ◽  
Author(s):  
Koji Mori ◽  
Takao Iino ◽  
Ken-Ichiro Suzuki ◽  
Kaoru Yamaguchi ◽  
Yoichi Kamagata
Keyword(s):  
16S Rrna ◽  
16S Rrna Gene ◽  
Tidal Flat ◽  
16S Rrna Genes ◽  
Rrna Genes ◽  
Acetate Metabolism ◽  
Rrna Gene ◽  
Marine Environments ◽  
Content Type ◽  
Tidal Flat Sediment

ABSTRACTAmong methanogens, only 2 genera,MethanosaetaandMethanosarcina, are known to contribute to methanogenesis from acetate, andMethanosaetais a specialist that uses acetate specifically. However,Methanosaetastrains so far have mainly been isolated from anaerobic digesters, despite the fact that it is widespread, not only in anaerobic methanogenic reactors and freshwater environments, but also in marine environments, based upon extensive 16S rRNA gene-cloning analyses. In this study, we isolated an aceticlastic methanogen, designated strain 03d30qT, from a tidal flat sediment. Phylogenetic analyses based on 16S rRNA andmcrAgenes revealed that the isolate belongs to the genusMethanosaeta. Unlike the other knownMethanosaetaspecies, this isolate grows at Na+concentrations of 0.20 to 0.80 M, with an optimum concentration of 0.28 M. Quantitative estimation using real-time PCR detected the 16S rRNA gene of the genusMethanosaetain the marine sediment, and relative abundance ranged from 3.9% to 11.8% of the total archaeal 16S rRNA genes. In addition, the number ofMethanosaetaorganisms increased with increasing depth and was much higher than that ofMethanosarcinaorganisms, suggesting that aceticlastic methanogens contribute to acetate metabolism to a greater extent than previously thought in marine environments, where sulfate-reducing acetate oxidation prevails. This is the first report on marineMethanosaetaspecies, and based on phylogenetic and characteristic studies, the name “Methanosaeta pelagica” sp. nov. is proposed for this novel species, with type strain 03d30q.

Aquisalimonas asiatica gen. nov., sp. nov., a moderately halophilic bacterium isolated from an alkaline, saline lake in Inner Mongolia, China

2007 ◽  
Vol 57 (5) ◽  
pp. 1137-1142 ◽  
Author(s):  
M. C. Márquez ◽  
I. J. Carrasco ◽  
Y. Xue ◽  
Y. Ma ◽  
D. A. Cowan ◽  
...  
Keyword(s):  
Inner Mongolia ◽  
Type Strain ◽  
Sequence Similarity ◽  
Halophilic Bacterium ◽  
16S Rrna Genes ◽  
Rrna Genes ◽  
Strictly Aerobic ◽  
Moderately Halophilic ◽  
Hybridization Data ◽  
Moderately Halophilic Bacterium

Two novel moderately halophilic, Gram-negative rods (strains CG12T and CG13) were isolated from Lake Chagannor in Inner Mongolia Autonomous Region, China. They were strictly aerobic and motile. They grew at pH 6.0–10.8 (optimally at pH 7.5–8.5), at 20–50 °C (optimally at 37 °C) and at salinities of 1–20 % (w/v) total salts (optimally at 7–10 %, w/v). Phylogenetic analysis of the two strains, based on a comparison of their 16S rRNA genes, led to their classification within the class Gammaproteobacteria, the closest recognized type strain being Alkalispirillum mobile DSM 12769T, with which they were found to share 94.4–94.6 % sequence similarity. On the basis of DNA–DNA hybridization data (showing 100 and 99 % relatedness for each other), the two isolates were found to be members of the same species. The DNA G+C contents of strains CG12T and CG13 were found to be 63.6 and 64.0 mol%, respectively. The major cellular fatty acids of strain CG12T, selected as the representative strain, were C18 : 1 ω7c, C16 : 0 and C12 : 0, and its polar lipids consisted of phosphatidylglycerol, diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylcholine, a phosphoglycolipid and six unidentified phospholipids. On the basis of the polyphasic evidence from this study, strains CG12T and CG13 represent a novel genus and species, for which the name Aquisalimonas asiatica gen. nov., sp. nov. is proposed. The type strain of Aquisalimonas asiatica is CG12T (=CCM 7368T=CECT 7151T=CGMCC 1.6291T=DSM 18102T).

scholarly journals Comparative Sequence Analysis of Mycobacterium leprae and the New Leprosy-Causing Mycobacterium lepromatosis

2009 ◽  
Vol 191 (19) ◽  
pp. 6067-6074 ◽  
Author(s):  
Xiang Y. Han ◽  
Kurt C. Sizer ◽  
Erika J. Thompson ◽  
Juma Kabanja ◽  
Jun Li ◽  
...  
Keyword(s):  
16S Rrna ◽  
Phylogenetic Trees ◽  
Mycobacterium Leprae ◽  
16S Rrna Genes ◽  
Rrna Genes ◽  
Neutral Evolution ◽  
Rrna Gene ◽  
Protein Encoding ◽  
Mycobacterium Lepromatosis ◽  
Encoding Genes

ABSTRACT Mycobacterium lepromatosis is a newly discovered leprosy-causing organism. Preliminary phylogenetic analysis of its 16S rRNA gene and a few other gene segments revealed significant divergence from Mycobacterium leprae, a well-known cause of leprosy, that justifies the status of M. lepromatosis as a new species. In this study we analyzed the sequences of 20 genes and pseudogenes (22,814 nucleotides). Overall, the level of matching of these sequences with M. leprae sequences was 90.9%, which substantiated the species-level difference; the levels of matching for the 16S rRNA genes and 14 protein-encoding genes were 98.0% and 93.1%, respectively, but the level of matching for five pseudogenes was only 79.1%. Five conserved protein-encoding genes were selected to construct phylogenetic trees and to calculate the numbers of synonymous substitutions (dS values) and nonsynonymous substitutions (dN values) in the two species. Robust phylogenetic trees constructed using concatenated alignment of these genes placed M. lepromatosis and M. leprae in a tight cluster with long terminal branches, implying that the divergence occurred long ago. The dS and dN values were also much higher than those for other closest pairs of mycobacteria. The dS values were 14 to 28% of the dS values for M. leprae and Mycobacterium tuberculosis, a more divergent pair of species. These results thus indicate that M. lepromatosis and M. leprae diverged ∼10 million years ago. The M. lepromatosis pseudogenes analyzed that were also pseudogenes in M. leprae showed nearly neutral evolution, and their relative ages were similar to those of M. leprae pseudogenes, suggesting that they were pseudogenes before divergence. Taken together, the results described above indicate that M. lepromatosis and M. leprae diverged from a common ancestor after the massive gene inactivation event described previously for M. leprae.

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