An Investigation of Cellulolytic Bacteria from Kimchi

Abstract:

Goal:

This study aims to isolate bacteria from kimchi with the ability to digest cellulose and to characterise selected isolates using DNA sequencing.

Background:

First-generation biofuels, which are generated from food sources such as sugar cane or maize, are neither economically efficient nor ethical. In contrast, second-generation biofuels are made from agricultural, industrial or municipal organic waste, which is considerably more sustainable. However, plant cellulose requires pre-processing to release fermentable sugars and a biological approach may ensure this step is both environmentally and economically viable. Kimchi is a traditional Korean fermented food made from vegetables that derives its sweetness from the microbial breakdown of cellulose. This study therefore aims to identify some of the bacterial strains involved since they may be useful for the pre-processing of cellulosic waste.

Methods:

Six different samples of kimchi were used: 3 freshly fermented and 3 packaged products. A 1 mL portion of the liquid component of each sample was centrifuged (8,000 g) and serial-diluted with 0.9% saline. 100 μL aliquots of each sample were transferred to MRS (De Man, Rogosa, and Sharpe) agar, LB agar, and CMC (carboxymethylcellulose) agar plates and incubated at 32 ℃ overnight. Cellulolytic activity could be identified by clear zones around colonies on CMC plates stained with aqueous iodine. Selected colonies were streaked and passaged on LB agar plates. Genomic DNA was extracted using a PureLink Genomic DNA Mini Kit and subsequently sequenced by Illumina MiSeq.