Sugary kefir mass and metabolite productions under different fermentation conditions

Name: Phattaraporn Sarikkha

keyword: Kefir grains

LCSH: Kefir

; Lactic acid

LCSH: Metabolites

; Metabolites

LCSH: Fermentation

; Wastewater treatment

; Sugary kefir

; PCR-DGGE analysis

; Microbial community

; Gluconobacter japonicus

; Saccharomyces cerevisiae

; Candida ethanolica

Abstract: Kefir is a microbial symbiotic mixture of lactic acid bacteria, acetic acid bacteria and yeast. In this study, sucrose aqueous solutions and wastewaters were utilized as a media for sugary kefir growth and metabolite formation. Both batch and repeated-batch conditions were explored and found the maximum kefir mass after 3 days of cultivation. For repeated-batch fermentations, the feeding cycles varied from 1-7 days and sucrose concentrations were among 1-10% (w/v). The maximum kefir mass gain was 0.47 g/100 mL in 3% (w/v) sucrose, 3- day repeated feeding cycle, and agitation rate of 90 rpm. For the maximum metabolite productions, the kefir was cultured in 10 % (w/v) sucrose solution under repeated 3-day feeding cycle for 27 days. The metabolite concentrations of lactic acid, acetic acid, and ethanol were 25.91, 5.41, and 0.71 g/L, respectively. Sugary kefir was capable of utilizing molasses and cassava in synthetic wastewaters. Molasses gave the maximum kefir mass yield of 30.95 mg/g COD removed/d. Similarly, sugar, cassava, and daily mill wastewaters were utilized by sugary kefir. The finding offers a potential application for a preliminary treatment of food processing wastewaters as well as to convert organic matters into valuable metabolites. The microbial diversity of sugary kefir was identified by Polymerase Chain Reaction-Denaturing Gradient Gel Electrophoresis (PCR-DGGE) analysis. The V3 regions of 16S bacterial rDNA and 18S rDNA of yeasts in both kefir grains and kefir fermentates were analyzed. Acetic acid bacteria Gluconobacter japonicus and Bacillus cereus were identified with 99% similarity to the GenBank database. Lactic acid bacteria species, including Lactobacillus rhamnosus, Lactobacillus perolens, Lactobacillus paracasei, and Bacilli bacterium were also identified with less than 97% similarity. Gluconobacter japonicas and Bacillus cereus were the most bacteria species found in sugary kefir grain and culture. Two yeast species, namely Saccharomyces cerevisiae, Candida ethanolica, were identified with 99% similarity to the GenBank database. However, yeast species Dekkera bruxellensis was identified with less than 97% similarity. Sugary kefir grains and fermentates have a higher diversity of bacterial communities than yeast communities. This study is the first time to find the yeast Candida ethanolica in sugary kefir. The microbial community of sugary kefir grain based on scanning electron microscope consists of lactic acid bacteria, acetic acid bacteria, and yeast. Morphology of sugary kefir grains revealed that bacteria and yeasts are spread throughout the grains. Yeast communities are located on the outer portion of kefir grains and the bacterial communities are located on the inner portion of kefir grains

Thammasat University. Thammasat University Library

Address: BANGKOK

Email: preserv@tu.ac.th

Name: Rachnarin Nitisoravut

Role: advisor

Created: 2014

Modified: 2022-01-06

Issued: 2022-01-06

วิทยานิพนธ์/Thesis

application/pdf

DOI: 10.14457/TU.the.2014.419

eng

DegreeName: Master of Science

Level: Master's Degree

Descipline: Technology

Grantor: Thammasat University

©copyrights Thammasat University

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