Genomica Analysis Of Carbon Source Metabolism Of Komagataeibacter Xylinus B2-1 And Study On The Production Of Bacterial Cellulose Using The Extract Of Soapberry Shell

Bacterial cellulose(Bacterial Cellulose,BC)is a new type of biopolymer material synthesized by microorganisms.Due to its unique properties,bacterial cellulose has wide application prospects in food processing,medical,textile,electronic products and other industries.But the current low output and high cost of BC limit its industrial production and application.Therefore,how to increase BC output at low cost and high efficiency has become an urgent problem to be solved.In this study,a BC producing strain was isolated and its entire genome was sequenced.By analyzing its genomic characteristics and key functional genes related to BC synthesis and regulation,the BC synthesis ability of the strain was predicted.Investigate the effect of carbon source type on BC synthesis,and successfully synthesize BC using the Sapindus mukorossi Gaert extract as raw material.The mechanism of BC synthesis was initially explored from the perspective of metabolism through IAA as a production-increasing factor of BC.The main research contents are as follows:A BC productioning strain was isolated from the bacterial membrane of Fujian's "Civil Chabao".The whole genome was sequenced and identified as Komagataeibacte xylinus r genus,named B2-1.Analysis of its genome sequence revealed that the B2-1 genome was annotated in the KEGG database with a large number of open reading frames(ORFs)related to BC synthesis,including 12 ORFs genes directly related to BC synthesis and regulation,which are involved in energy metabolism and carbon There are 216 source-related ORFs,and there are more than ten kinds of ORFs that regulate the metabolism of carbon source.Combined with the synthetic pathway of BC,it can be speculated that this strain has a diversity of BC synthetic substrates.Analysis of the cellulose synthase(BCs)in the BC synthesis system found that there are four ORFs of BCs annotated in KEGG,including the cellulose synthase genes such as BCs A,BCs B,BCs C,and BCs Z and the bgl X prosthetic group.However,the common BCs D operon is not annotated and the BCs Z operon structure exists.Analysis of the BC regulatory system(c-di-GMP system)revealed that the genes fol B,cpd P,phn P,glp Q and bdc A jointly regulate c-di-GMP.Based on genome-wide analysis,seven carbon sources were selected as substrates for BC synthesis.The results showed that the yield of BC with fructose and glucose as carbon sources was higher,2.31 g/L and 1.92 g/L,respectively.In addition,the structure and performance of BC from different carbon sources were also different.The water absorption performance of all BCs is not much different,but the rehydration shows a large difference.The rehydration rate of BC produced by sorbitol and mannitol is the highest(91.9% and 92.1%),followed by glucose,and the rehydration rate of BC produced by lactose is the lowest.70.2%.The microstructure of BC was characterized,and it was found that although their morphology was different,they were all nano-level fiber filaments and had a large number of hydrophilic functional groups.The glucose produced as BC had the highest crystallinity.In order to reduce the production cost of BC,the first attempt was to use the Sapindus mukorossi Gaert as the raw material for BC synthesis.First,acid hydrolysis was used to extract the polysaccharides of the Sapindus mukorossi shells.After four single factors were investigated,orthogonal optimization experiments were carried out.The results showed that the highest yield of polysaccharides extracted by acid hydrolysis was 50.3%.Using the Sapindus mukorossi Gaert extract as the raw material,the conditions for the synthesis of BC by strain B2-1 were optimized,and it was found that the highest BC yield(1.3-1.6 g/L)was obtained at a temperature of 30 °C,a p H of 6,and a solid-liquid ratio of 1: 8.,and continuous culture is better than batch culture fermentation.Interestingly,the strain B2-1 has a higher utilization rate of carbon source than that of glucose when the extract of the seedless plant is used as the substrate.The microstructure of BC produced by the Sapindus mukorossi Gaert extract and Hestrin–Schramm(HS)medium was found to be basically consistent.The above results indicate that the extract of the Sapindus mukorossi Gaert shells is expected to replace the commercial carbon source synthesized by BC,which greatly reduces the production cost of BC.Exogenous substances such as organic acids,tea polyphenols,and IAA were added to the medium to detect the effect of increasing production on BC synthesis.As a result,it was found that the addition of 6 mg/L of IAA increased BC production by about 35% to 2.47g/L.Adding IAA contributes to the increase of biomass and the consumption of carbon sources.By measuring the activities of six key enzymes in the carbon source metabolic pathway and the BC synthesis pathway,IAA was found to have an overall enhanced effect on the activities of these key enzymes,which can explain the reason why IAA promotes BC synthesis from a metabolic perspective.