Corrigendum: Genome-Based Genetic Tool Development for Bacillus methanolicus: Theta- and Rolling Circle-Replicating Plasmids for Inducible Gene Expression and Application to Methanol-Based Cadaverine Production

摘要

In the original article, there was a mistake in Table 2 as published. The cadaverine concentrations reported were miscalculated and overestimated by 41.6%, because the HPLC standard solution consisted of “cadaverine dihydrochloride (175.1 g/mol)” and not “cadaverine (102.18 g/mol).” The corrected Table 2 appears below. Table 2 Fed-batch methanol fermentation production data of strains MGA3(pBV2mp- cadA ) and MGA3 (pTH1mp- cadA ). Strain CDW ~(a) μ ~(b) Asp ~(c) Glu ~(c) Ala ~(c) Lys ~(c) Cad ~(c) g/L h ~(?1) g/L g/L g/L g/L g/L MGA3(pBV2mp- cadA ) 60.9 0.38 1.6 72.2 9.2 0.5 10.2 MGA3(pTH1mp- cadA ) 65.5 0.45 1.5 71.8 10.2 0.0 6.5 Mean values of duplicate cultures for B. methanolicus MGA3(pBV2mp-cadA) are shown. Deviation did not exceed 10%.The MGA3(pTH1mp-cadA) data was imported from N?rdal et al. ( 2015 ). CDW, cell dry weight; μ, specific growth rate; Asp, l-aspartate; Glu, l-glutamate; Ala, l-alanine; Lys, l-lysine; Cad, cadaverine . a Biomass concentrations are maximum values from the stationary growth phase . b Specific growth rates are maximum values calculated from the exponential growth period . c Cadaverine and amino acid concentrations are maximum values and volume corrected . Because of the error reported above, a correction has been made to the Abstract : “ Bacillus methanolicus is a thermophilic methylotroph able to overproduce amino acids from methanol, a substrate not used for human or animal nutrition. Based on our previous RNA-seq analysis a mannitol inducible promoter and a putative mannitol activator gene mtlR were identified. The mannitol inducible promoter was applied for controlled gene expression using fluorescent reporter proteins and a flow cytometry analysis, and improved by changing the ?35 promoter region and by co-expression of the mtlR regulator gene. For independent complementary gene expression control, the heterologous xylose-inducible system from B. megaterium was employed and a two-plasmid gene expression system was developed. Four different replicons for expression vectors were compared with respect to their copy number and stability. As an application example, methanol-based production of cadaverine was shown to be improved from 6.5 to 10.2 g/L when a heterologous lysine decarboxylase gene cadA was expressed from a theta-replicating rather than a rolling-circle replicating vector. The current work on inducible promoter systems and compatible theta- or rolling circle-replicating vectors is an important extension of the poorly developed B. methanolicus genetic toolbox, valuable for genetic engineering and further exploration of this bacterium.” Additionally, a correction has been made to the Results, Cadaverine Production From Methanol by Expression of a Heterologous Lysine Decarboxylase Gene From a Theta-Replicating Plasmid: “The plasmids pTH1mp and pBV2mp, containing the mdh promoter were used to study cadaverine production in B. methanolicus during fed-batch methanol fermentation. We have previously reported a methanol-based cadaverine production titer of 6.5 g/L by B. methanolicus MGA3 (pTH1mp- cadA ), a strain overexpressing the lysine decarboxylase cadA gene from E. coli (corrigendum to N?rdal et al., 2015 ). We compared cadaverine production in the strain overexpressing cadA from a theta-replicating plasmid during high cell density fed-batch fermentation. The B. methanolicus strain MGA3 (pBV2mp- cadA ) was tested in duplicates under comparable fermentation conditions. Samples for cadaverine and amino acid analysis, cell dry weight and OD _(600) were taken throughout the cultivation. As presented in Table 2 , we obtained a cadaverine production titer of 10.2 g/L based on the alternative theta-replicating pBV2mp plasmid. A substantial 55% production increase compared to the previously reported (pTH1mp- cadA )-based strain was observed. While biomass and by-product levels were similar between the two strains, the specific growth rate of MGA3 (pBV2mp- cadA ) was lower than that of MGA3 (pTH1mp- cadA ) ( Table 2 ).” Lastly, in the original article, the reference for “(N?rdal et al., 2015 )” was incorrectly written as “N?rdal, I., Pfeifenschneider, J., Brautaset, T., and Wendisch, V. F. (2015). Methanol-based cadaverine production by genetically engineered Bacillus methanolicus strains. Microb. Biotechnol . 8, 342–350. doi: 10.1111/1751-7915.12257”. It should be “N?rdal, I., Pfeifenschneider, J., Brautaset, T., and Wendisch, V. F. (2015). Methanol-based cadaverine production by genetically engineered Bacillus methanolicus strains. Microb. Biotechnol . 8, 342–350. doi: 10.1111/1751-7915.12257. Microb. Biotechnol . 2019, 12, 182-183”. The authors apologize for these errors and state that this does not change the scientific conclusions of the article in any way. The original article has been updated.