Optimization of biomass production of Acetobacter pasteurianus KU710511 as a potential starter for fruit vinegar production

Abstract

The objective of the present work was first the isolation of novel acetic acid bacteria strains from natural Moroccan habitats, and then, the evaluation of their ability to produce microbial starters for vinegar production on a large scale. The strains were isolated from figs, dates, cactus, and traditional fruit vinegars. Four strains, selected from a total of 63 isolates, were confirmed as belonging to Acetobacter species according to biochemical and molecular studies based on 16s rRNA sequence analysis. Acetous fermentation tests, performed on date and apple fermented juices using selected Acetobacter strains, showed a high capacity of acidification. The most efficient strain KU710511, isolated from Morrocan cactus (Opuntia ficus-indica), was identified as Acetobacter strain closely related to A. pasteurianus and yielded 42.5 g/L acidity in apple juice. Cell growth optimization was carried out for KU710511 using response surface methodology (RSM). The linear, quadratic, and interaction effects of four factors-ethanol, acetic acid, glucose concentrations and pH-were studied by the application of a central composite design. Thirty experiments were designed to predict the maximum concentration of cell biomass. The optimal calculated values of ethanol, acetic acid, glucose and pH allowing the prediction of the maximum biomass production (2.21 g/L) were 28.18, 10.12, 15.15 and 5.33 g/L, respectively. Subsequently, further batch fermentations were carried out in a 6-L labbioreactor at optimal conditions. The results were in line with the predicted values. It can be concluded that the studied strain is well suited to be used as a parental strain to prepare a starter for fruit vinegar production.

Inoculation with acetic acid bacteria improves the quality of natural green table olives

“…From more than 60 isolates, three microbial strains were selected to carry out experiments aimed at the preparation of natural table olives. These strains, namely : Lactobacillus plantarum S1, Saccharomyces cerevisiae LD01 and Acetobacter pasteurianus KU710511 (CV01) were identified using biochemical and molecular techniques and characterized in previous studies (Mounir et al, 2018;Mounir et al, 2016a;Mounir et al, 2016b;Mounir et al, 2016c) The determination of chloride, titratable acidity, pH, and counts of LAB, yeasts and AAB were carried out using the methods described in the Material and methods section. Then, samples were presented to tasters to evaluate their organoleptic quality.…”

“…The microbiological, physicochemical and sensory analyses carried out demonstrated the possibility of introducing a new process for producing natural table olives. In this method, we used a starter composed of two strains, namely Acetobacter pasteurianus KU710511 (CV01) and Lactobacillus plantarum S1 under the optimal conditions of AAB growth as reported by Mounir et al, (2016b) with 6% NaCl and alternating aeration of 8 hours/day.…”

“…It has also been reported that vinegar may be added to the brine solution to preserve the olives, adjust the pH, and impart a particular flavor (Colmagro, 2001). Thus, following our research, it seemed appropriate to consider three species of microorganisms: Lactobacillus plantarum S1, Saccharomyces cerevisiae LD01 and Acetobacter pasteurianus KU710511 CV01 isolated from Morocco (Mounir et al, 2016a;Mounir et al, 2016b;Mounir et al, 2016c;Mounir et al, 2018) The overall objective of our work was to develop a method for the preparation of natural table olives using locally selected microorganisms and without resorting to the usual techniques. This objective involves optimizing the synergy conditions between the selected microorganisms.…”

Molecular identification of acetic acid bacteria isolated from fermented mango juices of Burkina Faso: 16S rRNA gene sequencing

“…On the Carr medium, the production of the acid in the medium by strain can be seen in form of clearing of opacity of medium or the colour change of bromocresol green confirms that the isolate is Acetobacter species. Sharafi et al, (2010); Mounir et al, (2016) had reported that color change of the indicator bromocresol green in the medium from green to yellow confirm that the isolate is Acetobacter. The production of acid acetic of this strains was previously determined by Ouattara et al, (2018), where it was shown that these strains had the capacity to produce a high concentration of acetic acid and the highest was found with strain CRSBAN-BVA1.…”

“…Prefermented mango were transferred in a GYEA enrichment medium containing of glucose 2% (w/v), yeast extract 1% (w/v), ethanol 2% (v/v) and acetic acid 1% (v/v). Samples were incubated under agitation (120 rpm) at room temperature (30°C) for one week (Mounir et al, 2016). A volume of 100 μl from different dilutions were inoculated in GYC solid medium (10% glucose, 1.0% yeast extract, 2.0% calcium carbonate, 1.5% agar, pH 6.8) supplemented with 100 mg l -1 of Cycloheximide and nystatine were to inhibit the growth of fungi and lactic acid bacteria, respectively (Sharafi et al, 2010;Kadere et al, 2008).…”