A Modified, Efficient and Sensitive pH Indicator Dye Method for the Screening of Acid-Producing Acetobacter Strains Having Potential Application in Bio-Cellulose Production

• Published in: Applied biochemistry and biotechnology 2020-06, Vol.191 (2), p.631-636
• Main Authors: Kumar, Manoj, Tanoj, Nipunta, Saran, Saurabh
• Format: Article
• Language: English
• Subjects: Acetic Acid; Acetobacter - classification; Acetobacter - metabolism; Acids; Acids - analysis; Acids - metabolism; Bacteria; Biochemistry; Biotechnology; Calcium carbonate; Cellulose; Cellulose - biosynthesis; Chemistry; Chemistry and Materials Science; Coloring Agents - chemistry; Culture Media - chemistry; Ethanol; Fermentation; Hydrogen-Ion Concentration; Indicators and Reagents; Mass Screening - methods; Microorganisms; Oxidation; pH effects; Screening; Solubilization; Vinegar
• ISSN: 0273-2289; 1559-0291
• DOI: 10.1007/s12010-019-03211-x

It is imperative that promising bacterial cellulose-producing bacteria mainly belongs to genera Acetobacter (acid-producing bacteria). In order to screen cellulose-producing Acetobacter , the isolated cultures from vinegar/rotten fruits were inoculated in Hestrin-Schramm (HS) medium containing ethanol and CaCO 3 . After the desired incubation, the positive cultures form a zone, which is observed around the bacterial growth, resulted from the solubilization of CaCO 3 by acetic acid produced from the oxidation of ethanol during fermentation. However, in this method, the clarity of the solubilized zone is not very sharp and distinct. In the present, investigation, an improved method for screening, of the microorganisms producing acetic acid has been developed. In this method, methyl red (MR) is incorporated as a pH indicator in HS medium containing ethanol and CaCO 3 . Plates containing MR at alkaline pH are yellow and turn dark red at acidic pH. Thus, a distinctive, clear zone is formed around bacterial colonies producing acetic acid and is easy to differentiate between acid producers and non-producers. The present method is more rapid, accurate, and sensitive and can be successfully be used for the detection of acetic acid-producing bacteria particularly for the screening of potent cellulose producer Acetobacter sp.