5 g bacto tryptone 5 g bacto soytone 5 g meat digest 2 . 5 g yeast digest 0 . 5 g ascorbic acid 0 . 25 g mgso 4 19 g disodium - β - glycerolphosphate in 1 l deionized h 2 0 1 ml 2 × m1 0 . 5 ml 2 m sucrose 50 μl 20 % glucose 40 μl 1 m mgcl 2 4 μl 1 m cacl 2 406 μl h 2 o 60 g na 2 hpo 4 30 g kh 2 po 4 , 10 g nh 4 cl 5 g nacl . 50 mm co 3 - buffer 2 mm mgso 4 0 . 1 mm cacl 2 0 . 5 % casiton ( difco ) 0 . 5 % glucose in 1 liter h 2 o l . lactis mg1363 is a plasmid and prophage free derivative of the l . lactis strain ncdo 712 ( gasson , 1983 ). both the murine as well as the human egf ( accession number x04571 for hegf and nm 010113 for megf ) are available in the public databases at the national center for biotechnology information ( accession number x04571 for hegf and nm — 010113 for megf ). the coding sequences were adapted to optimize the expression in lactococcus . on the base of these sequences , primer sets were designed to assemble the optimized coding sequences of both hegf and megf . at the 3 ′ end of the coding sequence , a spei restriction site was introduced . the primers are shown in table 1 ( hegf ) and table 2 ( m egf ). 1 μl of each oligonucleotide is added to 10 μl taq buffer , 8 μl 2 mm mg 2 + , 2 μl 0 . 5 mm xtp , 5 u taq dna polymerase ( boehringer , mannheim , germany ) and 1 u pfu dna polymerase ( promega , madison , usa ). the reaction mixture is added up to 100 μl with water . the pcr reaction is carried out for 300 seconds at 94 ° c ., followed by 30 times the cycle of 45 seconds at 94 ° c ., 30 seconds at 48 ° c . and 30 seconds at 72 ° c ., with a final step of 10 seconds at 15 ° c . after the assembly , hegf and megf are amplified in a pcr mixture containing 1 μl vent dna - polymerase ( new england biolabs , beverly , usa ), 10 μl taq buffer , 4 μl 0 . 5 mm xtp , 5 μl 0 . 5 μm of each primer , 1μl template dna , 1 μl mm mg 2 so 4 and 74 μl h 2 o . in the case of hegf , hegf01 and hegf06 were used as primer ; for megf , megf01 and megf06 were used . for hegf , the same temperature schedule was used as for the first step . in the case of megf , the hybridization step was carried out at 52 ° c . in stead of 48 ° c . after the assembly , the size of the optimized gene fragments was confirmed on a 2 % agarose gel . spei cut assembled egf ( both for hegf and megf ) is ligated into a naei and spei digested pt1nx ( steidler et al ., 1995 ), resulting in pt1hegf and pt1megf . a schematic overview of the construction of pt1hegf is shown in fig1 . plasmids are transformed into competent cells of l . lactis by electroporation . 50 μl of cells are electroporated in a precooled cuvet of 2 mm , at 25 μf , 2 . 5 kv and 400 ω ( bio - rad electroporator ). l . lactis is made competent by growing a 1 / 100 dilution of a saturated culture , in 200 ml gm17 with 2 . 5 % glycine , until an od 600 of 0 . 5 ( wells et al ., 1993 ). after electroporation , 1 ml of recuperation medium is added , and the cells are incubated for 1 . 5 hour at 28 ° c . cells are plated on gm17 solid medium , comprising 5 μg / ml erythromycin . for the transformation of l . casei , plasmid is isolated from l . lactis on a qiagen - tip 100 , according to the instructions of the manufacturer . the dna is transformed into competent l . casei cells . l . casei cells are made competent by growing a 1 / 50 dilution of an overnight culture in 50 ml mrs ( oxoid ltd ., basingstoke , hampshire , england ) with 1 % glycine at 37 ° c ., untill an od 600 of 0 . 6 . the cells are harvested and washed twice with 10 ml 5 mm na 3 po 4 ph 7 . 4 , 1 mm mgcl 2 , and resuspended in 500 μl electroporation buffer ( 0 . 3 m sucrose , 5 mm na 3 po 4 ph 7 . 4 , 1 mm mgcl 2 ). 10 μl of dna is added to 50 μl of competent cells and the electroporation is carried out in a biorad electroporator . after electroporation , 450 μl mrs is added and the cells are incubated for two hours at 37 ° c . cells are plated on mrs agar with 5 μg / ml erythromycin . the presence of the plasmid is confirmed using pcr . the transformed l . lactis strains mg1363 [ pt1nx ], mg1363 [ pt1megf ] and mg1363 [ pt1hegf ] are pitched in 5 ml gm17 comprising 5 μg / ml erythromycin , and grown overnight at 30 ° c . this preculture is diluted 1 / 100 in 5 ml gm17 with erythromycin , and incubated for three hours at 28 ° c . the culture is centrifuged and resuspended in bm9 expression medium , and incubated overnight at 28 ° c . the transformed l . casei strains are grown under similar conditions , but using mrs as preculture , and bm9 as expression medium . to the culture supernatant , 1 / 10 volume sodium desoxycholate is added , and the mixture is kept on ice for 10 minutes . 1 / 10 of volume 100 % tca is added and the mixture is incubated on ice for 15 minutes . after centrifugation , the pellet is dissolved in 50 μl h 2 o and 50 μl 1 m tris - hcl ph 9 . 5 . the proteins are analyzed on a 20 % laemmli protein gel . detection is carried out using a western blot , with mouse polyclonal anti hegf and rabbit anti megf as primary antibodies . alkaline phosphatase labeled anti - mouse and anti - rabbit secondary antibodies were from southern biotechnology ( birmingham , usa ). the results are summarized in fig2 . in vivo testing of mice , using the transformed lactic acid bacteria strains in order to assess the effect of the transformed lactic acid bacteria and the growth of the villi and the gut adsorption , seven groups of balb / c mice ( iffa credo cr broekman / sulzfield ) were treated either with a megf or hegf expressing lactic acid bacterium strain . l . lactis and l . casei transformed with an empty vector pt1nx , or with bm9 medium was given to mice as a negative control . 600 μl of l . casei is pitched in 15 ml mrs with 10 μg / ml erythromycin . in the case of l . lactis , gm17 is used instead of mrs , and only 5 μg / ml erythromycin is used for selection . l . casei is incubated overnight at 37 ° c ., for l . lactis , 30 ° c . is used . the overnight culture is harvested by centrifugation , and the pellet is resuspended in 1 . 5 ml bm9 expression medium . 100 μl of this solution is supplied daily , for a period of four weeks . at the end of the experiment , the mice are sacrificed and the intestine is isolated . the tissue is fixated in buffered formaldehyde and thin sections are colored using hematoxylin and eosin g , for microscopic analysis of the villi . the length of the villi is measured at several points to obtain a representative average . all sections were taken from the terminal ileum . the results are summarized in fig3 . l . casei [ pt1hegf ], especially , has a positive effect on villus growth and should promote gut absorption . carpenter c . d ., ingraham h . a ., cochet c ., walton g . m ., lazar c . s ., sodawski j . m ., rosenfeld m . g . and gill g . n . 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the present invention relates to epidermal growth factor producing lactic acid bacteria and their use to increase intestinal villi height and to promote gut absorption . in particular , the invention relates to egf producing lactococcus lactis and lactobacillus casei . the organisms may be especially useful to treat short bowel syndrome .