Isolation and characterization ofBacillus thioparussp. nov., chemolithoautotrophic, thiosulfate-oxidizing bacterium

Abstract

A novel bacterium, strain BMP-1(T), was isolated from a continuous wastewater treatment culture system operating with a bacterial consortium. Cells of the isolate were Gram-variable, aerobic, moderately halotolerant, motile and endospore-forming rods. Strain BMP-1(T) grew chemolithoautotrophically by oxidation of thiosulfate to sulfate with a growth yield of 1.07 g protein mol(-1) of thiosulfate consumed. DNA G+C content was 43.8 mol%. Its cell wall had peptidoglycan based on m-diaminopimelic acid, and the major component of fatty acid was C(15 : 0). The 16S rRNA gene analysis showed that strain belongs to the genus Bacillus, sharing a 99.5% of sequence similarity with Bacillus jeotgali CCM 7133(T). DNA-DNA hybridization between the isolate of this study and this strain was 44%. Thus, the inclusion of strain BMP-1(T) in the genus Bacillus is suggested as a novel species and the name Bacillus thioparus sp. nov. (Type strain BMP-1(T)=BM-B-436(T)=CECT 7196(T)) is proposed. The sequence of the 16S rRNA gene has been deposited in GenBank with accession number DQ371431.

Bacillus stamsii sp. nov., a facultatively anaerobic sugar degrader that is numerically dominant in freshwater lake sediment

“…The major fatty acid was iso-C 15:0 with 48.8% of the total fatty acid content. Similar results were shown earlier for the closely related strains B. thioparans (77.3% iso-C 15:0 , [21]) and B. jeotgali (49.3% iso-C 15:0 [56]). Detailed results of the fatty acid analysis are summarized in Table 1.…”

“…Yet, the type of metabolism is already known for other bacteria like Thiobacillus denitrificans [11]. In our hands, strain BoGlc83 did not grow lithoautotrophically with thiosulfate as this was shown earlier for B. thioparans [21]. Yet, during auxotrophic growth in the presence of yeast extract and casamino acids, optical densities increased and elemental sulfur was detected in the cultures while part of the thiosulfate was consumed.…”

“…However, nitrate reduction was incomplete in batch cultures and most of the nitrate present in the cultures accumulated as nitrite. Nitrate reduction is rather common in Bacillus strains, however, oxidation of thiosulfate as an electron source for nitrate reduction within the genus Bacillus has so far been described only for B. thioparans [21,35]. Yet, the type of metabolism is already known for other bacteria like Thiobacillus denitrificans [11].…”

“…But the fact that during both aerobic and anaerobic growth 1 mol of thiosulfate is converted to 2 mol of elemental sulfur indicates that thiosulfate serves as electron acceptor rather than as electron donor for strain BoGlc83. Thiosulfate oxidation as in B. thioparans or Thiobacillus intermedius would yield sulfite and sulfate as intermediates or end products [3,21], which could never be detected in cultures of strain BoGlc83.…”

“…Strain BoGlc83 belongs to the genus B. according to previous 16S-rRNA gene analyses [18]. Its closest described relatives are B. thioparans (similarity 98.91% [21]), Bacillus subterraneus (similarity 98.51% [12]), B. jeotgali (similarity 98.44% [56]), Bacillus boroniphilus (similarity 98.31% [1]), and Bacillus selenatarsenatis (similarity 98.30% [54]) after analyzing the 16S rRNA gene sequence of Bacillus strain BoGlc83 using the EzTaxon Identify tool [13]. In addition, the 16S rRNA gene sequence of Bacillus strain BoGlc83 was aligned with the 16S rRNA gene sequence of the taxonomically undescribed Bacillus sp.…”