Since obtaining the target gene is the first step of genetic engineering, production flow of BGI starts from library group. The major task of library group is constructing and screening genomic library and cDNA library.
　　The whole genomic library is an aggregation of recombinant DNA clone of random fragments covering particular organism's entire genome. In order to construct a library, genome DNA is cut into fragments in particular length through mechanical cutting or enzymolysis and then recombined with suitable vector in random and cloned. Genomic DNA library is widely used in analysis and separation of particular gene fragment, regulating gene expression, study of human and propagation genetic engineering.
　　The quality of library has direct effect on following work and sequencing quality. Transformation is a process of vector DNA comes into receptive cell (a cell that is more susceptive of taking outer DNA) and then obtains genetic information. Transformation is the key step of large-scale sequencing and provides primary raw material.
　　By making use of this feature, we can transform target DNA fragment (namely recon) into receptive cell and then replicate with recon in large amount in the process of bacteria propagation. By doing screening work through antibiotics and color-developing agent, the cells carrying target recons are obtained. The common transformation methods are chemical transformation and electronic transformation. Since electronic transformation has advantages of high efficiency and convenience, we use electronic transformation method. We now use bacteria strain of DH5α and DH10B as receptor cell. Since PUC18 is used as vector for constructing library, LB solid culture substrate containing aminobenzylpenicillin and spreaded with x-gal and IPTG is used as screening medium.
　　The success of transformation relies on high quality library, high efficient receptive cell and appropriate screening method.

Culture group

　　Established in July 2001, Culture group is a new group in BGI. The major task of group is bacterium culture that spread bacterium liquid on solid medium and growing single clone on substrate. Thereafter, transfer these single clones into 96well plate containing liquid culture medium, after incubation overnight, the bacteria are ready for template group. Culture group plays important roll in production although established very late.

Template group

　　Template group prepares template DNA for sequencing reaction. The quality of template DNA directly affects quality of sequencing reaction. Alkaline degradation and following membrane filter are used to make template DNA. The principle of extracting target substance, the PUC18 plasmid inserted DNA fragment, from recon obtained by transformation: after denaturation, the plasmid DNA and bacterium chromosome DNA renatured in deferent period of time due to the deference of their structure complexity, plasmid DNA dissolved since renatured completely, on the contrary, bacterium chromosome DNA and proteins form large conglomeration, and therefore two of them are separated. After additional precipitation and washing, template DNA with high purity is obtained. Template group produce 50000 clones each day.

Electrophoresis-DNA transfering group

　　The purpose of running electrophoresis is inspecting the quality of library and template and provides reference amount for sequencing reaction. Electrophoresis is in common use to separate and purify DNA fragments. Following electrophoresis step, large amount of high quality DNA is transferred into enzyme linked immunosorbent assay plate. At the time of transferring, the samples containing impurity and large amount of protein are eliminated and therefore improve the sequencing quality and the chance of success.
　　Usually we use agarose gel as porous supporting medium which containing electrolyte. When agarose gel sets in electrostatic field, DNA molecules move towards anode because of negative charges bearing on phosphate radical residue on the both sides of double helix backbone of DNA molecules. The ratio of driving force coming from electrostatic field to resistance force coming from gel become smaller while DNA molecule is longer and results different movement rate. That is why we can separate DNA molecules by their length. Electrophoresis is carried out for sample and molecular weight reference standard that also used to determine the length of DNA molecules.
　　Agarose gel electrophoresis is suitable to separate DNA fragments ranging from 0.2Kb to 50Kb.

Liquid preparing group

　　Liquid preparing group takes charge of reagent preparing work for all sequencing process, involving library group, culture group, template group, electrophoresis group, reaction group and 377 group and therefore is a foundation of all production and scientific activities that keeps our Institute in good shape.
　　The daily works of liquid preparing group are preparing liquid reagents, solid reagents and plates. The quality affects the level of sequencing quality of Institute.

Reaction group

　　Reaction group play an important roll in sequencing work. The quality of work carried out by this group affects the cost and quality of sequencing.
　　The work of reaction group follows after template preparing made by electrophoresis group. Template transfer, sequencing reaction and purifying sequencing products are carried out through proofreading and judgment. Template transferring process moves the samples from four 96 well plates to one 384 well plate which improve the efficiency of PCR instrument. We amplify and label template DNA through Sanger terminal ending method. The purification of sequencing product is the process of eliminating ion and impurity from amplified gene fragments.
　　The current daily output of reaction group is 100 thousand clones and is moving toward large-scale and automation. With 35 PCR apparatus, we can carry out fifty 384 well plates at a time. We replaced manual liquid adding operation by making use of Qfill2、hydra and high throughput automatic liquid distributing station.

MegaBACE group

　　MegaBACE group is the last step from template preparing to produce base, from here, the "data"- sequence of AGCT base in DNA produced. The major wok of MegaBACE group is carried out by MegaBACETM1000 sequencers which utilizing capillary technology. Since heat disperse quickly due to the small aperture and large surface area of capillary, we can use higher voltage to shorten electrophoresis time, and therefore increase the turnout of single sequencer. Comparing to flat sequencer, such as 377, that is the big advantage of capillary sequencer. Moreover, by using Matrix, capillary sequencer has the advantage of high resolving power and enduring high voltage. MegaBACE group has 104 MegaBACE sequencers that are capable of running 100 thousand reactions and produce 50 million base pairs.
　　With the features of easy to operate (automatic), safe (non isotope), accurate (controlled by computer) and quick, MegaBACETM1000 automatic sequencers provided hardware to carry out important projects and even China part of international HGP.

377 group

　　The name of 377 group followed after 377 sequencer of PE company. 377sequencer uses flat electrophoresis with polyacrylamide gel. The features of 377sequencer are high quality sequencing, requiring lower template quality and longer valid reading length.
　　At present, coordinated with other department of BGI, 377group conducts some sequencing work in small project. Eleven 377sequencers and two 3730 sequencers undertake tasks of sequencing less than 10000 base pairs to serve external units. 377group was the major battlefield undertaking 1% international HGP and made great contribution to completion of 1% international HGP. "There is no short cut in scientific work, date is of overriding importance!" is the oath we stand by. That old "experimental desk " built by containers is the best witness of our hard works.