Isolation of Acetic Acid Bacteria and Preparation of Starter Culture for Apple Cider Vinegar Fermentation

Abstract

Vinegars are commonly used as food condiments and preservatives. Apple cider vinegar (ACV) is also used in the Ayurvedic pharmaceutical industry because of its medicinal properties. Since specifically selected starter cultures for commercial vinegar production are not readily available, apple juice supplemented with sugar is commonly inoculated with a microbiologically undefined culture obtained from the previous batch of ACV. The present work focuses on the isolation of yeasts and acetic acid bacteria from ACV and the preparation of a starter culture. ACV was produced in a bench scale bioreactor using a traditional fermentation process wherein an acetic acid concentration of 3.8% was obtained after three weeks. Several acetic acid bacteria (AAB) were isolated from ACV using selective media. Microscopy revealed the cultures to be gram negative to gram variable short rods. The growth pattern of the isolates on differential media and biochemical tests suggested the presence of Acetobacter and Gluconobacter species. Ten potent isolates were selected for starter culture preparation. Two consortia were formulated with five AAB isolates in each along with a yeast isolate and used for ACV production, wherein an acetic acid concentration of 4.2%-4.9% was obtained in 10-12 days. Thus, these two starter cultures with locally isolated AAB can be used for the commercial production of apple cider vinegar.

Antibiotic sensitivity test of Escherichia coli and Staphylococcus aureus isolated from the reproductive tract of dairy cows

“…The yellow colour indicated the presence of mannitol fermentation. Mannitol, which was the acid produced, caused the phenol red colour of the agar to change from red to yellow (Mathew et al, 2019). Yellow colonies that grew on MSA media were then subjected to Gram staining.…”

Draft genome sequence of Staphylococcus auricularis PAPLE_T1 isolate of Carica papaya revealing biosynthetic clusters for beneficial metabolites

“…From each dilution, 0.1 mL was plated on Carr’s (yeast extract 3%, agar 2%, bromocresol green 0.002%, ethanol 2%) and Frateur’s media (yeast extract 10 g/L, ethanol 20 g/L, agar 20 g/L, calcium carbonate 20 g/L, and distilled water 1 L) and incubated for 3–7 days. Bacterial colonies were purified by streaking in fresh Frateur’s medium ( 10 , 11 ). For useful insights on S. auricularis PAPLE_T1 intrinsic potentials, its entire genome was sequenced maintaining default parameters.…”

Screening and Characterization of New Acetobacter fabarum and Acetobacter pasteurianus Strains with High Ethanol–Thermo Tolerance and the Optimization of Acetic Acid Production

“…Pure bacterial colonies underwent macro and microscopic observations by studying the shape, size, arrangement, Gram staining, pigmentation and motility test, by inoculating the colonies in YPG medium at an incubation temperature of 30 • C for 72 h. Classical biochemical tests, such as catalase activity, cytochrome oxidase, growth in peptone, presence of pigmentation in YPG medium and growth on YPG medium containing D-glucose > 30% were used according to the protocol described by [5,39]. Acetate oxidation and ethanol overoxidation to C 2 O and H 2 O were performed to distinguish between the genera Acetobacter and Gluconobacter.…”