Characterization of Komagataeibacter Isolate Reveals New Prospects in Waste Stream Valorization for Bacterial Cellulose Production

Abstract

Komagataeibacter spp. has been used for the bioconversion of industrial wastes and lignocellulosic hydrolysates to bacterial cellulose (BC). Recently, studies have demonstrated the capacity of Komagataeibacter spp. in the biotransformation of inhibitors found in lignocellulosic hydrolysates, aromatic lignin-derived monomers (LDMs) and acetate. In general, detoxification and BC synthesis from lignocellulosic inhibitors requires a carbon flow from acetyl-coA towards tricarboxylic acid and gluconeogenesis, respectively. However, the related molecular aspects have not yet been identified in Komagataeibacter spp. In this study, we isolated a cellulose-producing bacterium capable of synthesizing BC in a minimal medium containing crude glycerol, a by-product from the biodiesel production process. The isolate, affiliated to Komagataeibacter genus, synthesized cellulose in a minimal medium containing glucose (3.3 ± 0.3 g/L), pure glycerol (2.2 ± 0.1 g/L) and crude glycerol (2.1 ± 0.1 g/L). Genome assembly and annotation identified four copies of bacterial cellulose synthase operon and genes for redirecting the carbon from the central metabolic pathway to gluconeogenesis. According to the genome annotations, a BC production route from acetyl-CoA, a central metabolic intermediate, was hypothesized and was validated using acetate. We identified that when K. rhaeticus ENS9b was grown in a minimal medium supplemented with acetate, BC production was not observed. However, in the presence of readily utilizable substrates, such as spent yeast hydrolysate, acetate supplementation improved BC synthesis.

Characterization, genome analysis and genetic tractability studies of a new nanocellulose producing Komagataeibacter intermedius isolate

“…Four bcs operons were annotated in K. intermedius ENS15. As previously reported for Komagataeibacter spp 4 , 5 , 9 , 10 , 37 , only one operon contained the complete genes set encoding the BC biogenesis machinery ( bcsAI , bcsBI , bcsCI and bcsD ) was found in K. intermedius ENS15 genome (genomic position 1,511,250:1,520,353 bp). Though annotated as individual genes, a manual search identified a 14 bp overlap within bcsAI and bcsBI genes ( bcsABI ) and 1 bp overlap between bcsCI and bcsD .…”

“…The operon contained, in the order, the genes encoding phosphoenolpyruvate-protein phosphotransferase and the phosphocarrier protein, PTS fructose transporter subunit IIA, and a bifunctional kinase/phosphorylase (involved in catabolite repression and phosphorylation of phosphocarrier protein). Similar to other Komagataeibacter spp., K. intermedius ENS15 genome did not indicate an annotation for the gene encoding phosphofructokinase (catalysing the conversion of fructose 6 phosphate to fructose 1,6-biphosphate) resulting in an incomplete Embden-Meyerhof-Parnas (EMP or glycolytic) pathway 9 , 10 . In Komagataeibacter spp., glucose oxidation takes two routes, either via glucose-6-phosphate (entering into pentose phosphate pathway, PPP) or through gluconate generation (through the catalytic activity of glucose dehydrogenase).…”

“… Bacterial strains Medium supplements a Production titer (g/L) References Glucose Komagataeibacter sp. W1 – 1.2 41 K. rhaeticus AF1 2% Ethanol 4.1 3 K. rhaeticus PG2 – ~ 4 42 K. rhaeticus ENS9a – 1.4 9 K. rhaeticus ENS9b – 0.6 10 G. xylinus – 1.3 43 K. xylinus B-12068 3% Eth 2.2 44 G. xylinus CGMCC 2955 – ~ 3.3 45 K. hansenii JR-02 2% Eth ~ 1.2 46 K. hansenii B22 – 1.6 7 K. intermedius FST213-1 – 1.2 40 K. intermedius JF2 – …”

“…W1 – 1.2 41 K. rhaeticus AF1 2% Ethanol 4.1 3 K. rhaeticus PG2 – ~ 4 42 K. rhaeticus ENS9a – 1.4 9 K. rhaeticus ENS9b – 0.6 10 G. xylinus – 1.3 43 K. xylinus B-12068 3% Eth 2.2 44 G. xylinus CGMCC 2955 – ~ 3.3 45 K. hansenii JR-02 2% Eth ~ 1.2 46 K. hansenii B22 – 1.6 7 K. intermedius FST213-1 – 1.2 40 K. intermedius JF2 – 1.2 39 K. intermedius ENS15 – 1.1 ± 0.1 This study Pure gly...…”

Bitter friends are not always toxic: The loss of acetic acid bacteria and the absence of Komagataeibacter in the gut microbiota of the polyphagous fly Anastrepha ludens could inhibit its development in Psidium guajava in contrast to A. striata and A. fraterculus that flourish in this host

“…Besides, many Komagataeibacter species can synthesize enzymes as tannase, polyphenol oxidase, and pectinase, which are used in incomplete oxidation to metabolize a wide range of tannins and polyphenols, as gallic, tannic, gentisic, vanillic, caffeic, syringic, coumaric and ferulic acids ( Usha-Rani and Anu-Appaiah, 2012 ; Chakravorty et al, 2016 ; Emiljanowicz and Malinowska-Pańczyk, 2019 ; Vasconcellos et al, 2019 ; Netzel et al, 2020 ). Thus, considering the robust tannin-degrading metabolic machinery among Komagataeibacter species ( Cannazza et al, 2021 ), we suggest that this genus could perform important metabolic activities in A. striata and A. fraterculus that allow these flies to successfully develop in guava. We surmise that Komagataeibacter could degrade toxic guava compounds, allowing the development of A. striata and A. fraterculus larvae in this fruit, producing a symbiotic relationship with the benefit of adding a detoxification capacity.…”