Comparative inhibitory effects of sodium and potassium chloride salts on Staphylococcus aureus from fermented Pentaclethra macrophylla

Aim: The study was conducted to evaluate comparatively the individual effects of sodium (NaCl) and potassium (KCl) chloride salts against Staphylococcus aureus isolated from fermented Pentaclethra macrophylla.
Method: A total of twenty (20) traditionally fermented food samples (Pentaclethra macrophylla) were purchased from a market in Umuahia metropolis. Isolation and identification of Staphylococcus aureus were conducted using standard microbiological techniques. Staphylococcus aureus was identified using standard morphological and biochemical tests. The inhibitory effect of both salts (NaCl and KCl) were analyzed on modified nutrient agar and nutrient broth (Media + 5% salt conc., Media + 10% salt conc., Media + 15% salt conc., Media + 20% salt conc.). The study measured culture growth using optical density readings at 425nm over 48 hours with different NaCl and KCl concentrations, while growth on plates was visually assessed on colony counter.
Results: The highest optical density recorded as a result of contact with varying concentration of sodium chloride was 0.48 at 5% concentration after 48hours incubation while the least was 0.04 at 20% concentration after 12hours incubation while the highest optical density recorded as a result of contact with varying concentration of potassium chloride was 0.41 at 5% concentration after 48hours incubation while the least was 0.01 at 20% concentration after 12hours incubation.
Conclusion: Higher salt concentrations resulted in osmotic shock, suppressing growth in Staphylococcus aureus, but increased salt concentration partially alleviated growth inhibition over time.