Kiyoshi Kadowaki

Transfer of Bacillus alginolyticus, Bacillus chondroitinus, Bacillus curdlanolyticus, Bacillus glucanolyticus, Bacillus kobensis, and Bacillus thiaminolyticus to the genus Paenibacillus and emended description of the genus Paenibacillus

We determined the taxonomic status of six Bacillus species (Bacillus alginolyticus, Bacillus chondroitinus, Bacillus curdlanolyticus, Bacillus glucanolyticus, Bacillus kobensis, and Bacillus thiaminolyticus) by using the results of 16S rRNA gene sequence and cellular fatty acid composition analyses. Phylogenetic analysis clustered these species closely with the Paenibacillus species. Like the Paenibacillus species, the six Bacillus species contained anteiso-C15:0 fatty acid as a major cellular fatty acid. The use of a specific PCR primer designed for differentiating the genus Paenibacillus from other members of the Bacillaceae showed that the six Bacillus species had the same amplified 16S rRNA gene fragment as members of the genus Paenibacillus. Based on these observations and other taxonomic characteristics, the six Bacillus species were transferred to the genus Paenibacillus. In addition, we propose emendation of the genus Paenibacillus.

Proposal for two new genera, Brevibacillus gen. nov. and Aneurinibacillus gen. nov.

16S rRNA gene sequences of the type strains of 11 species belonging to the Bacillus brevis and Bacillus aneurinolyticus groups were determined. On the basis of the results of gene sequence analyses, these species were separated into two clusters. The B. brevis cluster included 10 species, namely, Bacillus brevis, Bacillus agri, Bacillus centrosporus, Bacillus choshinensis, Bacillus parabrevis, Bacillus reuszeri, Bacillus formosus, Bacillus borstelensis, Bacillus laterosporus, and Bacillus thermoruber. Bacillus aneurinolyticus and Bacillus migulanus belonged to the B. aneurinolyticus cluster. Moreover, the two clusters were phylogenetically distinct from other Bacillus, Amphibacillus, Sporolactobacillus, Paenibacillus, and Alicyclobacillus species. On the basis of our data, we propose reclassification of the B. brevis cluster as Brevibacillus gen. nov. and reclassification of the B. aneurinolyticus cluster as Aneurinibacillus gen. nov. By using 16S rRNA gene sequence alignments, two specific PCR amplification primers were designed for differentiating the two new genera from each other and from other aerobic, endospore-forming organisms.

Emended description of Paenibacillus amylolyticus and description of Paenibacillus illinoisensis sp. nov. and Paenibacillus chibensis sp. nov.

The taxonomic position of unidentified group 6 of Bacillus circulans as described by Nakamura and Swezey (L.K. Nakamura and J. Swezey, Int. J. Syst. Bacteriol. 33:46-52, 1983) was determined, and the taxonomy of Paenibacillus amylolyticus was reexamined. The results of PCR amplification of a 16S rRNA gene fragment with a specific primer and comparative analysis of 16S rRNA gene sequences warranted placing the two taxa in the genus Paenibacillus. The levels of DNA reassociation among the strains revealed four groups (designated groups I, II, III, and 6), each with a high level of intragroup relatedness (> 72%). Clustering based on phenotypic characteristics correlated well with DNA relatedness grouping. P. amylolyticus strains were scattered in groups I, II, and III. Strains labeled the type strain of P. amylolyticus from different culture collections appeared in groups I and III. Strains found in group I were identified as P. amylolyticus sensu stricto, and the one strain found in group III was identified as Paenibacillus lautus. Group 6 encompassed strains formerly assigned to B. circulans group 6, and group II contained other strains identified as P. amylolyticus. Groups 6 and II were phenotypically and genetically distinct taxa that were distinguishable from the previously described species. These findings showed that groups 6 and II were new species, for which we propose the names Paenibacillus illinoisensis and Paenibacillus chibensis, respectively.

Characterization of Bacillus brevis with descriptions of Bacillus migulanus sp. nov., Bacillus choshinensis sp. nov., Bacillus parabrevis sp. nov., and Bacillus galactophilus sp. nov.

Thirty-five Bacillus brevis strains obtained from culture collections, including protein-producing isolates, were taxonomically studied by using numerical analysis, DNA base composition, and DNA-DNA hybridization. Six DNA relatedness groups were represented, and these groups correlated well with clusters based on the numerical analysis. The B. brevis strains were separated into B. brevis sensu stricto, four new species, and an unidentified species of the genus Bacillus. Bacillus migulanus sp. nov., Bacillus choshinensis sp. nov., Bacillus parabrevis sp. nov., and Bacillus galactophilus sp. nov. are proposed.

Proposal of Bacillus reuszeri sp. nov., Bacillus formosus sp. nov., nom. rev., and Bacillus borstelensis sp. nov., nom. rev.

Taxonomic studies of 26 putative Bacillus brevis strains (12 strains formerly assigned to groups 2, 4 through 7, and B and 14 ungrouped strains) were carried out. These organisms were placed in five distinct groups on the basis of phenotypic characteristics, the results of DNA base composition and reassociation analyses, and the results of cellular fatty acid and isoprenoid quinone composition analyses. Group 2, which contained three strains, was identified as Bacillus choshinensis, and group 4, which contained one strain, was identified as Bacillus parabrevis. The three remaining unidentified groups were clearly distinguishable phenotypically and genetically from the type strains of B. brevis and the recently described species Bacillus agri, Bacillus centrosporus, Bacillus migulanus, Bacillus choshinensis, and Bacillus parabrevis. Therefore, the names Bacillus reuszeri sp. nov., Bacillus formosus sp. nov., nom. rev., and Bacillus borstelensis sp. nov., nom. rev. are proposed for groups 5 (3 strains), 6 (3 strains), and 7 (16 strains), respectively. The S-layer proteins found in the three new species were immunologically and genetically similar to the S-layer proteins found previously in B. brevis, B. agri, B. centrosporus, B. choshinensis, and B. parabrevis. The G+C content of NRRL NRS-1206, the type strain of B. reuszeri sp. nov., was 46.5 mol%; the G+C content of NRRL NRS-863, the type strain of B. formosus sp. nov., nom. rev., was 47.2 mol%; and the G+C content of NRRL NRS-818, the type strain of B. borstelensis sp. nov., nom. rev., was 51.3 mol%.

Pilot scale production of a recombinant human epidermal growth factor, secreted by Bacillus brevis, using expanded bed adsorption

Recombinant Bacillus brevis which carried an expression plasmid encoding the human epidermal growth factor (EGF) gene on a cryptic high-copy number plasmid, pHT926, extracellularly produced EGF in its biologically active form at a concentration of over 1.5 g L−1 in the culture broth in a 30-L jar fermenter. The culture broth also contained some other EGF compounds, which mainly consisted of oligomeric and polymeric forms with disulfide bonds. We developed a simple purification method for EGF, without prior cell removal from the culture broth, comprising cation exchange expanded bed adsorption followed by ultrafiltration with UF 10 000 and 3000 membranes. The EGF compounds were efficiently separated from the EGF in its native form in the expanded bed adsorption step. With this purification method, only EGF in its native form was recovered from the culture broth, with a yield of nearly 80%, and 90% purity. This efficient and economic system has made it possible to use EGF as a pharmaceutical in the livestock industry.

The Efficient Production of Human Epidermal Growth Factor by Bacillus brevis

A system has been developed for the efficient production of heterologous proteins using Bacillus brevis as a host that secretes large amounts of cell wall protein into the medium. The promoter region and signal peptide-encoding region of the cell wall protein gene were used to construct an expression-secretion vector. Bacterial proteins such as amylases can be produced in large amounts by this system (1 g/l or more), but mammalian proteins such as human alpha-amylase are produced at a low level (one or two orders of magnitude less than for bacterial proteins). The highly efficient secretion of human epidermal growth factor (h-EGF, more than 1 g/l) was obtained with B. brevis HPD31 as the host and plasmid pHY481, derived from B. brevis 481, as the vector. Recombinant hEGF was purified easily from the culture supernatant by two steps. Purified hEGF had the identical NH2-terminal amino acid sequence and COOH-terminal amino acid sequence with those of the authentic hEGF, and it was fully active in biological assays. This recombinant hEGF has been shown to be successful for biological wool harvesting (CSIRO, Australia). These results, in combination with previous results, indicate that foreign proteins of diverse origins can be produced efficiently as functional proteins in B. brevis.

Bacillus aneurinolyticus sp. nov., nom. rev.

The taxonomic position of “Bacillus aneurinolyticus” was determined by numerical analyses based on phenotypic characteristics and whole-cell proteins profile, chemosystematic data, DNA base composition, and DNA relatedness. “B. aneurinolyticus” strains were separated into “B. aneurinolyticus” and Bacillus migulanus by DNA relatedness. This result correlated well with the clusters obtained from numerical analyses based on phenotypic characteristics and whole-cell proteins profile. “B. aneurinolyticus” was clearly distinct from other Bacillus species phenotypically and genetically. We propose the revival of the name Bacillus aneurinolyticus.

Bacillus galactophilus Is a Later Subjective Synonym of. Bacillus agri

We confirm that Bacillus galactophilus Takagi, Shida, Kadowaki, Komagata, and Udaka 1993 is a later subjective synonym of Bacillus agri Nakamura 1993 on the basis of chemosystematic data and DNA relatedness data.

Differentiation of species in the Bacillus brevis group and the Bacillus aneurinolyticus group based on the electrophoretic whole-cell protein pattern.

Ninety strains of eleven Bacillus species in the Bacillus brevis group and the Bacillus aneurinolyticus group were compared with the electrophoretic whole-cell protein pattern. The strains were separated into two clusters at the similarity of 55%. One cluster (cluster 1) was consisted of strains from the B. brevis group, and another cluster (cluster 2) was composed of strains from the B. aneurinolyticus group. The cluster 1 was separated into eight subclusters. Out of eight subclusters, seven subclusters contain strains from B. brevis, B. laterosporus, B. agri, B. reuszeri, B. choshinensis, B. formosus, and B. borstelensis. Another subcluster was further separated into two related clusters, which corresponded to B. centrosporus and B. parabrevis, and they were fused at the similarity of 76%. Cluster 2 was separated into two subclusters, which corresponded to B. aneurinolyticus and B. migulanus. The above eleven species showed characteristic patterns distinct from one another, and this correlated well with the published DNA relatedness data. The comparison of the electrophoretic whole-cell protein pattern proved to be useful for evaluation of taxonomic relationships among these taxa.