Exploring Antimicrobial Activity of Crab Bacterial Isolates Against Potential Marine Pathogens (2023)
Undergraduate: Klodia Badal
Faculty Advisor: Alecia Septer
Department: Earth, Marine, and Environmental Sciences
Globally, an increasing number of pathogens are evolving resistance to our current antibiotics, signaling the need for new antibiotics. While 70% of our current antibiotics were discovered from terrestrial microbes, marine bacteria are an understudied source of potential new antibiotics.
Previous research has shown that bacteria isolated from shrimp, lobster, and squid eggs have antimicrobial activity that protects eggs against infections. This study investigates similar activity in mud crab eggs collected from the North Carolina coast. Twenty-one bacteria were isolated from two of the crabs, Eurypanopeus depressus and Petrolisthes armatus. These crab isolates were tested against marine bacteria isolated from seawater collected off the coast of North Carolina which may be potential pathogens. Crab isolates were tested in a zone of inhibition assay, where liquid cultures were plated on to a lawn of the potential pathogens, Alteromonas, Pseudoalteromonas, or Ruegeria. After 24-72 h, isolates with a zone of clearance around them were marked as antimicrobial and the zone was measured. Antimicrobial isolates were identified by PCR and sequencing of the 16S rRNA gene. Of the 21 strains (3 trials) tested, the results showed that 8 strains inhibited Ruegeria, 2 inhibited Alteromonas, and 2 inhibited Pseudoalteromonas. The PCR results revealed that isolates YC_C9D and C15_03 are Vibrios; YC_C8D and YC_C9C are Pseudoalteromonas'; C17_14 is Leisingera; and C17_15, C17_16, and C17_17 are Shewanella.
In the future along with further studies and experiments, these findings assist in the creation of new antibodies.