Crayfish broth for bacterial culture

To formulate a new growth medium for bacteriological studies.

Sun dried white shrimps, Nematopalaemon hastatus, were ground into fine powder and infused in distilled water at 7+/-1 degrees C for 24 h. The pH of the infusion was adjusted to 7.2 with NaOH (0.1 m) and HCl (0.1 m) and evaporated to dryness. Crayfish broth (CB) was produced by reconstituting the concentrate in distilled water and sodium chloride was added at 0.9% w/v. Crayfish infusion agar (CIA) and crayfish starch agar (CSA) were prepared with CB as nutrient base. The crayfish broth and agar were evaluated alongside with nutrient broth and agar (Oxoid) for ability to support growth of pathogens such as Escherichia coli, Klebsiella aerogenes, Pseudomonas aeruginosa, Staphylococcus aureus and Enterococcus faecalis. Crayfish broth was tested for suitability for sugar fermentation and indole test and results compared with those obtained with peptone water. Its suitability as a sensitivity test medium was evaluated using ampicillin (10 microg) and gentamicin (10 microg) discs and results compared with those obtained using Mueller-Hinton agar (Oxoid).

Crayfish broth comprises crayfish infusion concentrate 3.5 g and sodium chloride 9.0 g dissolved in one litre of distilled water. The crayfish broth, CSA supported the growth of the test pathogens with cultural characteristics similar to those seen on nutrient agar. The pH of the spent crayfish broth was near neutral (pH 6.9). The broth was as important as peptone water for sugar fermentation test but was not suitable for indole test. The results of antibiotic susceptibility test on CIA were comparable with those obtained on Mueller-Hinton agar with difference in zone diameters of not more than 1 mm.

Crayfish broth possesses enormous potential as a new growth medium for bacterial studies.