Cephalosporin is a β-lactam antibiotic produced by Acremonium chrysogenum using submerged fermentation. Carbon and nitrogen are the most influential medium ingredients for cephalosporin formation. The purpose of this study was to obtain the best composition of media for cephalosporin C production. Response surface methodology was used for production optimization. The results showed that molasses of 70 g/L was the best carbon source, while the best nitrogen source was the combination of corn steep liquor, urea and ammonium sulphate. DL-methionine, carbon, and nitrogen source significantly affected the production of cephalosporin C. The mathematically modelled optimization showed that the highest production of cephalosporin C (3876 mg/L) was obtained using medium composition of 68.28 g/L molasses, 71.61 g/L nitrogen, and 0.4 g/L DL-methionine. Laboratory verification using the same medium composition produced 3696 mg/L of cephalosporin C, being 4.65% different from the mathematically optimized results. Medium optimization increased the cephalosprin C production which was 1.48 times higher than that using the previous medium, where the maximum production was only 2487 mg / L. ABSTRAK Sefalosporin C adalah golongan antibiotik β-lactam yang dihasilkan Acremonium chrysogenum melalui fermentasi cair. Komponen yang sangat berpengaruh terhadap produksi sefalosporin C adalah sumber karbon dan nitrogen. Penelitian ini bertujuan mendapatkan komposisi media terbaik untuk produksi sefalosporin C. Optimasi dilakukan menggunakan metode respon permukaan. Hasil menunjukkan bahwa molases 70 g/L adalah sumber karbon terbaik dan kombinasi corn steep liquor, urea dan ammonium sulfat adalah sumber nitrogen terbaik. DL-methionin, sumber karbon, dan nitrogen berpengaruh nyata terhadap produksi sefalosporin C. Optimasi menggunakan model matematika menunjukkan produksi sefalosporin C tertinggi (3876 mg/L) yang diperoleh dengan komposisi media 68,28 g/L molases, 71,61 g/L nitrogen, dan 0,4 g/L DL-methionin. Verfikasi di laboratorium menggunakan komposisi media yang sama menghasilkan sefalosporin C sebesar 3696 mg/L, berbeda 4,65% dibanding dengan hasil optimasi matematis. Optimasi media mampu meningkatkan produksi sefalosprin C sebesar 1,48 kali dibanding media yang digunakan sebelumnya, dimana maksimal hanya menghasilkan 2487 mg/L.
β-lactam antibiotics are widely used in clinic. Filamentous fungus Acremonium chrysogenum is an important industrial fungus for the production of CPC, one of the major precursors of β-lactam antibiotics. Although its fermentation yield has been bred significantly over the past decades, little is known regarding molecular changes between the industrial strain and the wild type strain. This limits the possibility to improve CPC production further by molecular breeding. Comparative transcriptome is a powerful tool to understand the molecular mechanisms of CPC industrial high yield producer compared to wild type. A total of 57 million clean sequencing reads with an average length of 100 bp were generated from Illumina sequencing platform. 22,878 sequences were assembled. Among the assembled unigenes, 9502 were annotated and 1989 annotated sequences were assigned to 121 pathways by searching against the Kyoto Encyclopedia of Genes and Genomes pathway (KEGG) database. Furthermore, we compared the transcriptome differences between a high-yield and a wild-type strain during fermentation. A total of 4329 unigenes with significantly different transcription level were identified, among which 1737 were up-regulated and 2592 were down-regulated. 24 pathways were subsequently determined which involve glycerolipid metabolism, galactose metabolism, and pyrimidine metabolism. We also examined the transcription levels of 18 identified genes, including 11 up-regulated genes and 7 down-regulated genes using reverse transcription quantitative -PCR (RT-qPCR). The results of RT-qPCR were consistent with the Illumina sequencing. In this study, the Illumina sequencing provides the most comprehensive sequences for gene expression profile of Acremonium chrysogenum and allows de novo transcriptome assembly while lacking genome information. Comparative analysis of RNA-seq data reveals the complexity of the transcriptome in the fermentation of different yield strains. This is an important public information platform which could be used to accelerate the research to improve CPC production in Acremonium chrysogenum.
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