Isolation of yeast and acetic acid bacteria from palmyra palm fruit pulp (Borassus flabellifer Linn.
The isolation and identification of yeast and acetic acid bacteria from palmyra palm fruit pulp were investigated. Twenty yeast isolates were selected from palmyra palm fruit sample. Ten yeast isolates showed the highest tolerant ability to 10 and 15% (w/v) glucose. To screening for ethanol tolerance with 6 and 8% (v/v) ethanol, the cell viability was obtained at 6% (v/v) ethanol than 8% (v/v) with a range 6.86 7.67 log CFU/ml and 2.20 4.00 log CFU/ml, respectively. The isolate Y15 produced the highest ethanol content about 7.4% at 15% (w/v) glucose within 4 days. This isolate was Candida stellimalicola with identification method of rRNA region and sequence of D1/D2 domain of rDNA. The isolates of acetic acid bacteria from palmyra palm fruit pulp were studied by the biochemistry test. The catalase test showed positive and oxidase test as negative. Microscopic examinations confirmed that the strains were gram negative rod to coccobacilli. All of strains showed negative overoxidation and cellulose formation. For ethanol tolerance, twenty acetic acid bacteria isolates were cultured in 6 and 8% (v/v) ethanol. Ten acetic acid bacteria isolates and tolerant ability to ethanol were subsequently screened with 6 and 8% (v/v) ethanol for acetic acid production. The isolate A10 produced the highest acetic acid content with 5.64% within 55 days at 6% (v/v) ethanol as compared with the other isolates. This isolate was identified as Acetobacter ghanensis, a new acetic acid bacteria for using native acetic acid bacteria strain as starter culture for palmyra palm fruit vinegar production.