METHODS AND RESULTS: The Rhizomucor pusillus proteinase (RPP) gene was sub-cloned into a pALF expression vector. The recombinant pALF-RPP vector was then electro-transferred into Lactococcus lactis. Finally, the milk coagulation ability of recombinant L. lactis carrying a RPP gene was evaluated. Nucleotide sequencing of DNA insertion from the clone revealed that the RPP activity corresponded to an open reading frame consisting of 1218 bp coding for a 43·45 kDa RPP protein. The RPP protein assay results indicated that the highest RPP enzyme expression with 870 Soxhlet units (SU) per ml and 7914 SU/OD were obtained for cultures which were incubated at pH 5·5 and 30°C. Interestingly, milk coagulation was observed after 205 min of inoculating milk with recombinant L. lactis carrying the RPP gene.
CONCLUSION: The recombinant L. lactis carrying RPP gene has the ability to function as a starter culture for acidifying and subsequently coagulating milk by producing RPP as a milk coagulant agent.
SIGNIFICANCE AND IMPACT OF THE STUDY: Creating a recombinant starter culture bacterium that is able to coagulate milk. It is significant because the recombinant L. lactis has the ability to work as a starter culture and milk coagulation agent.
METHODS: In this study, fbpA and mazE genes were chosen as new antimicrobial targets and treated with antisense peptide nucleic acid (PNA). Firstly, they were evaluated by bioinformatics and then analyzed by experimental procedures. Secondly, the functionality was evaluated by stress conditions.
RESULTS: Our results interestingly demonstrated that when fbpA and mazE loci of N. meningitidis were targeted by antisense PNA, 8 µM concentration of fbpA-PNA as well as 30 µM concentration of mazE-PNA inhibited the growth of N. meningitides and were found to be bacteriostatic, whereas 10 μM concentration of fbpA-PNA showed bacteriocidal activity.
CONCLUSION: Our findings demonstrated the bactriocidal activity of fbpA-PNA and bacteriostatic activity of mazEPNA. Therefore, mazE and fbpA genes should be potent antimicrobial targets but further analysis including in vivo analysis should be performed.
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