Project description:We reported that analysis of acid tolerance mechanism in Propionibacterium acidipropionici at gene expression level. Genome shuffling was performed on P. acidipropionici to improve the acid tolerance of the strain. Wild type strain P. acidipropionici CGMCC 1.2230 and acid-tolerant mutant P. acidipropionici WSH1105 were compared to find key genes involved in acid tolerance of P. acidipropionici during fermentation. Results provide important information on acid response of P. acidipropionici, such as genes encoded ABC-transporters, proteins involved in amino acids metabolism and propionic acid synthesis.
Project description:The parental P. acidipropionici and its genome-shuffled mutant were compared via metabolomics to find the key metabolic nodes influencing PA production.
Project description:Propionic acid (PA) is a three-carbon molecule commonly used as a food preservative and increasingly, as a precursor for the synthesis of monomers. Propionibacterium spp. are the best biological producers of PA. In fact, a recent report showed that if a yield of 0.6 g/g is achieved, biological production of PA would be economically competitive with petrochemical production. To achieve that yield, a library of Propionibacterium strains was used to generate a new strain that can achieve the commercially desirable yield from sucrose. The genome of the new strain was sequenced and a series of SNPs were found to be responsible for the improved phenotype. Using a combination of transcriptomics the relevant mutations were expounded. Differential RNA-sequencing between the wild-type and the mutant strain identified the relevant genomic changes responsible for the PA yield improvement. Notably, an increase in the specific consumption rate of sucrose was attributed to a SNP in the promoter region of a sugar transporter. Similarly, a mutation in a polar amino acid transporter improved acid tolerance, and an improvement in the electron transport system rewired the metabolism to yield an improved PA phenotype. These changes resulted in a lower acetic acid by-product generation and a higher PA yield. The productivity of the new strain was augmented with the design of a fed-batch process to achieve titres of 70 g/L through the use of a mathematically design fed-strategy.
Project description:Propionibacterium freudenreichii is an important starter culture used in the manufacture of Swiss-type cheeses. We have generated the complete genome sequence of a Propionibacterium freudenreichii ssp. shermanii strain JS at the Institute of Biotechnology, University of Helsinki, by using a combination of pyrosequencing with GS FLX and GS FLX Titanium series reagents (Roche) and SOLiD 4 (Life Technologies), ABI 3130xl Genetic Analyzer (Life Technologies), and PacBio RS II (Pacific Biosciences) instruments. Initial genome annotation was carried out using RAST, and additional functional annotation information for each CDS was obtained from BLANNOTATOR, CDD, and KAAS. Accession number for genome sequence is PRJEB12148. This submission is for the transcriptome analysis of Propionibakcterium freudenreichii in cheese ripening under warm and cold conditions. The RNA reads were mapped to the reference genome PRJEB12148.
Project description:Propionibacterium acidipropionici produces propionic acid as its main fermentation product. Traditionally derived from fossil fuels, environmental and sustainable issues have revived the interest in producing propionic acid using biological resources. Here, we present the closed sequence of Propionibacterium acidipropionici ATCC 55737, an efficient propionic acid producer.
