New integration vector using a cellulase gene as a screening marker for Lactobacillus.

Area of Science:

• Microbiology
• Molecular Biology
• Genetic Engineering

Background:

• Lactobacillus species are crucial in food production and human health.
• Efficient genetic manipulation tools are needed for these bacteria.
• Current screening methods can be inefficient or prone to false positives.

Purpose of the Study:

• To develop and validate a new integration vector, pJC4, for Lactobacillus.
• To utilize the extracellular endoglucanase A gene (celA) as a screening marker.
• To assess the efficacy of pJC4 in multiple Lactobacillus species.

Main Methods:

• Development of the pJC4 integration vector.
• Transformation of pJC4 into Lactobacillus johnsonii, Lb. gasseri, Lb. bulgaricus, and Lb. plantarum.
• Screening of transformants using cellulase activity on agar plates.
• Confirmation of integration using Polymerase Chain Reaction (PCR) and Southern hybridization.

Main Results:

• pJC4 was successfully transformed into four Lactobacillus species.
• A clear halo on cellulase plates accurately and easily identified pJC4 integrants.
• No false transformants were observed.
• PCR and Southern hybridization confirmed the presence of pJC4 in the chromosomal DNA of all positive transformants.

Conclusions:

• The pJC4 vector is an effective tool for integrating DNA into Lactobacillus species.
• The celA gene serves as a reliable and efficient screening marker for Lactobacillus transformation.
• This system facilitates genetic engineering of Lactobacillus and potentially other lactic acid bacteria.