Exploring K2G30 Genome: A High Bacterial Cellulose Producing Strain in Glucose and Mannitol Based Media

Abstract

Demands for renewable and sustainable biopolymers have rapidly increased in the last decades along with environmental issues. In this context, bacterial cellulose, as renewable and biodegradable biopolymer has received considerable attention. Particularly, acetic acid bacteria of the Komagataeibacter xylinus species can produce bacterial cellulose from several carbon sources. To fully exploit metabolic potential of cellulose producing acetic acid bacteria, an understanding of the ability of producing bacterial cellulose from different carbon sources and the characterization of the genes involved in the synthesis is required. Here, K2G30 (UMCC 2756) was studied with respect to bacterial cellulose production in mannitol, xylitol and glucose media. Moreover, the draft genome sequence with a focus on cellulose related genes was produced. A pH reduction and gluconic acid formation was observed in glucose medium which allowed to produce 6.14 ± 0.02 g/L of bacterial cellulose; the highest bacterial cellulose production obtained was in 1.5% (w/v) mannitol medium (8.77 ± 0.04 g/L), while xylitol provided the lowest (1.35 ± 0.05 g/L) yield. Genomic analysis of K2G30 revealed a peculiar gene sets of cellulose synthase; three bcs operons and a fourth copy of bcsAB gene, that encodes the catalytic core of cellulose synthase. These features can explain the high amount of bacterial cellulose produced by K2G30 strain. Results of this study provide valuable information to industrially exploit acetic acid bacteria in producing bacterial cellulose from different carbon sources including vegetable waste feedstocks containing mannitol.

Keywords: Komagataeibacter xylinus; bacterial cellulose; genome sequencing; gluconic acid; glucose; mannitol; xylitol.

FIGURE 1

K2G30 genome circular representation. From outside to inside: contigs with relative lenghts expressed in bp; coverage; GC skew expressed in positive changes in GC content (black) and negative (red); GC content expressed in percentage; forward CDS; reverse CDS; bcs operons genome localization.

FIGURE 2

The arrangement of bcs operons and BC related genes organization in K2G30.

FIGURE 3

ML tree representing the phylogenetic distances among 19 Komagataeibacter genomes. The node numbers indicate the bootstrap values. The branch length was expressed in 0.010 unit.

FIGURE 4

TETRA heatmap of 21 Komagataeibacter genomes sequences (derived from Supplementary Table S2). TETRA values are represented in the central bi-color gradient heatmap (red gradients ≥ 96%; white = 95%; blue gradients ≤ 94%).

FIGURE 5

BC produced by K2G30 in static (A) and agitated (B) conditions. From left to right: BC produced in mannitol, glucose, and xylitol, respectively.