[Construct cosmid libraries by isolating large genomic DNA fragments from Monascus ruber].

Area of Science:

• Molecular Biology
• Genomics
• Microbial Biotechnology

Background:

• Accurate genomic analysis requires high-quality, large-fragment DNA.
• Monascus ruber is a fungus with potential biotechnological applications.
• Cosmid libraries are essential for cloning large DNA inserts.

Purpose of the Study:

• To develop and validate a method for isolating large genomic DNA fragments from Monascus ruber.
• To construct a cosmid library using the isolated DNA.
• To demonstrate the feasibility of identifying specific genes within the library.

Main Methods:

• A modified phenol-chloroform extraction method was employed for DNA isolation.
• Genomic DNA was digested with Sau3AI to yield average 40kb fragments.
• DNA fragments were packaged into a cosmid library using Gigapack III XL packaging extract, followed by PCR screening for the polyketide synthase (PKS) gene.

Main Results:

• The isolation method yielded genomic DNA fragments averaging over 48 kb with a concentration of 5 microg/microl.
• The constructed cosmid library provided 10-fold coverage of the Monascus spp. genome.
• A cosmid containing a homologue of the PKS gene was successfully identified via PCR screening.

Conclusions:

• The modified method is efficient and feasible for isolating large genomic DNA fragments from Monascus ruber.
• This technique facilitates the construction of comprehensive cosmid libraries for Monascus species.
• The successful identification of the PKS gene homologue validates the utility of the cosmid library.