An auto-inducible phosphate-controlled expression system of Bacillus licheniformis

Abstract

BackgroundA promoter that drives high-level, long-term expression of the target gene under substrate limited growth conditions in the absence of an artificial inducer would facilitate the efficient production of heterologous proteins at low cost. A novel phosphate-regulated expression system was constructed using the promoter of the phytase encoding gene phyL from Bacillus licheniformis for the overexpression of proteins in this industrially relevant host.ResultsIt is shown that the phyL promoter enables a strong overexpression of the heterologous genes amyE and xynA in B. licheniformis when cells were subjected to phosphate limitation. Whether B. licheniformis can use phytate as an alternative phosphate source and how this substrate influences the PphyL controlled gene expression under growth conditions with limited inorganic phosphate concentrations were also investigated. It is shown that B. licheniformis cells are able to use sodium phytate as alternative phosphate source. The addition of small amounts of sodium phytate (≤ 5 mM) to the growth medium resulted in a strong induction and overexpression of both model genes in B. licheniformis cells under phosphate limited growth conditions.ConclusionsThe PphyL controlled expression of the investigated heterologous genes in B. licheniformis is strongly auto-induced under phosphate limited conditions. The proposed PphyL expression system enables an overexpression of target genes in B. licheniformis under growth conditions, which can be easily performed in a fed-batch fermentation process.Electronic supplementary materialThe online version of this article (10.1186/s12896-018-0490-6) contains supplementary material, which is available to authorized users.

Recent biotechnological advances and future prospective of Bacillus licheniformis as microbial cell factories

“…Recently, many high-quality elements have been innovatively developed at the transcriptional level, showing potential for applications in expression [78]. The relative lack of available promoters in B. licheniformis has been partially alleviated by the development of sugar alcohol, ammonium inducible promoters, phosphate limited dependent autoinducible type and strongly constitutive types [79][80][81]. Some excellent works have also focussed on how to precisely regulate the transcriptional capacity of the promoter.…”

Practical genetic control strategies for industrial bioprocesses

“…Examples include the depletion of, or switching between inexpensive fed sugars (Fig. 1 ; Bothfeld et al, 2017 ; Meyer et al, 2018 ), phosphate limitation (Nitta et al, 2021 ; Trung et al, 2019 ), or oxygen supply (Lange et al, 2017 ). Alternatively, pH (Li, C et al, 2020 ) or temperature shift (Wang et al, 2021 ), if consistent with the ideal process and infrastructure, could be employed.…”

Enhanced extracellular raw starch-degrading α-amylase production in Bacillus subtilis by promoter engineering and translation initiation efficiency optimization

“…Compared with constitutive promoters, inducible promoters have less influence on the growth of strains because they can control the expression cycle of target proteins. In past decades, many kinds of inducible promoter systems have been explored, such as tightly inducible expression systems induced by chemicals [ 18 ] and auto-inducible expression systems [ 19 ]. Compared with the chemical-dependent systems, auto-inducible phase-dependent expression systems without supernumerary inducers attracted much more attention because of their practical applications in the flexible and dynamic regulation of pathway genes [ 20 ].…”