A Bioengineered Nisin Derivative To Control Streptococcus uberis Biofilms

Area of Science:

• Microbiology
• Biochemistry
• Veterinary Medicine

Background:

• Antimicrobial peptides like nisin are crucial against multidrug-resistant bacteria.
• Streptococcus uberis causes bovine mastitis, forming biofilms that increase antibiotic resistance.
• Some S. uberis strains possess a nisin resistance system (NSR) that degrades nisin.

Purpose of the Study:

• To evaluate the efficacy of nisin PV, a nisin derivative resistant to NSR cleavage, against S. uberis biofilms.
• To compare the biofilm eradication and inhibition capabilities of nisin PV versus nisin A.

Main Methods:

• Crystal violet (biomass), XTT (viability) assays, and confocal microscopy were used to assess pre-established and developing biofilms.
• Two S. uberis strains were tested: DPC 5344 and ATCC 700407 (nsr).

Main Results:

• Nisin PV reduced biofilm biomass by over 60% and showed 42% greater viability reduction than nisin A.
• Nisin PV inhibited biofilm formation more effectively than nisin A, decreasing viability by up to 85% and showing a lack of biofilm or only dead cells.
• Confocal microscopy revealed more dead cells and reduced biofilm thickness with nisin PV treatment.

Conclusions:

• Nisin PV is a potent agent for eradicating and inhibiting S. uberis biofilms, particularly in NSR-producing strains.
• Nisin PV represents a promising alternative antimicrobial for managing bovine mastitis caused by S. uberis.
• These findings contribute to understanding bacteriocins and controlling S. uberis biofilms in mastitis.