pirA- and pirB-like gene identification in Micrococcus luteus strains in Mexico

Area of Science:

• Aquatic Animal Health
• Bacteriology
• Molecular Biology

Background:

• Acute Hepatopancreatic Necrosis Disease (AHPND) is a significant threat to shrimp aquaculture, first reported in China in 2009 and Mexico in 2013.
• AHPND is caused by Vibrio parahaemolyticus, which harbors pirA- and pirB-like genes responsible for toxin production.
• The presence of these genes in other bacterial genera prior to AHPND outbreaks is not well-documented.

Purpose of the Study:

• To investigate the presence of pirA- and pirB-like genes in bacterial genera other than Vibrio.
• To determine if these genes existed in Mexico before the documented AHPND outbreaks.

Main Methods:

• Selection of two bacterial isolates from shrimp farms in Nayarit, Mexico, collected in 2006.
• Analysis of isolates using nested-PCR to detect pirA- and pirB-like genes.
• Confirmation of gene presence and bacterial identification through DNA sequencing.

Main Results:

• The pirA- and pirB-like genes were detected in two bacterial isolates from Nayarit, Mexico.
• Sequencing confirmed the presence of these genes and identified both strains as Micrococcus luteus.
• This indicates pirA- and pirB-like genes were present in a novel bacterial species, M. luteus, prior to 2013.

Conclusions:

• The pirA- and pirB-like genes were identified in Micrococcus luteus, a previously unreported bacterial host for these AHPND-associated genes.
• These genes were present in Mexico in 2006, predating the first reported AHPND outbreak in China (2009) and Mexico (2013).
• This finding suggests a potential earlier origin or broader distribution of AHPND-associated genetic elements than previously understood.