Fluorescent Lactic Acid Bacteria and Bifidobacteria as Vehicles of DNA Microbial Biosensors

Abstract

Control and quantification of effector molecules such as heavy metals, toxins or other target molecules is of great biotechnological, social and economic interest. Microorganisms have regulatory proteins that recognize and modify the gene expression in the presence or absence of these compounds (effector molecules) by means of binding to gene sequences. The association of these recognizing gene sequences to reporter genes will allow the detection of effector molecules of interest with high sensitivity. Once investigators have these two elements—recognizing gene sequences and reporter genes that emit signals—we need a suitable vehicle to introduce both elements. Here, we suggest lactic acid bacteria (LAB) and bifidobacteria as promising carrier microorganisms for these molecular biosensors. The use of fluorescent proteins as well as food-grade vectors and clustered regularly interspaced short palindromic repeats (CRISPR) are indispensable tools for introducing biosensors into these microorganisms. The use of these LAB and bifidobacteria would be of special interest for studying the intestinal environment or other complex ecosystems. The great variety of species adapted to many environments, as well as the possibility of applying several protocols for their transformation with recognizing gene sequences and reporter genes are considerable advantages. Finally, an effort must be made to find recognizable gene sequences.

Purification and characterization of a phospholipid-hydrolyzing phosphoesterase produced by Pediococcus acidilactici isolated from Gouda cheese

“…The orange residues in Figure 2 represent DNA binding sites that play a key role in DNA reparation (Williams et al, 2008). Recently, these DNA binding properties have been used as a biosensor for control and quantification of effector compounds such as heavy metals and toxins (Landete and Arqués, 2017). The amino acids depicted in blue show conserved active sites identical to known metal ion-binding sites, which bind Fe 3+ , Mg 2+ , Mn 2+ , and Zn 2+ , coordinated by asparagine, aspartate, and histidine residues (Hopfner et al, 2001).…”