Instability of nata formation by Acetobacter aceti subsp. xylinum and a new nata-producing isolate using seaweed pulp extract

Eden  Mamaril,; Gerry  Galvez,

Instability of nata formation by Acetobacter aceti subsp. xylinum and a new nata-producing isolate using seaweed pulp extract

Discipline: agriculture, food and related studies

Abstract:

A total of nine (9) isolates from nata starter/ mother liquor and five (5) isolates from fresh seaweed pulp extract (SPE) were isolated and screened for ability to produce/ form nata pellicle in glocuse- yeast extract (GYE), Hassid and barker broth(HBB) and coconut water media (CWM). The best isolates EM23 from SPE and EFM from nata starter/ mother liquor proved to be stable in producing nata up to 4th transfer in sterile and up to 2nd transfer in non-sterile seaweed pulp extract medium (PEM). Contaminants significantly affected the formation of nata. Nata yields and total plate counts of the isolates decreased with increased total bacterial and yeast counts. Yeast species formed films on the surface of fermenting medium thus competed with the nata organisms for both space and oxygen. Contaminants were identified to be Candida, Saccharomyces, Acetobacter, Bacillus, Leuconostoc and Pediococcus. The buildup of these contaminants was accompanied with increases in pH and alcohol levels and increase in total acidity of the medium.

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