Ge n om e a t la s of t h e ch r om osom e of L . la ct is M G 1 3 6 3 . ifr . a c. u k
Ge n om e a t la s of t h e ch r om osom e of L . la ct is M G 1 3 6 3 . ifr . a c. u k
The sequence also led t o t he ident ificat ion of 29 genes t hat are required t o build t he m esh - like pept idoglycan com ponent of t he bact erium 's cell wall. I nducing som e of t hese enzym es can accelerat e t he slow , expensive process of cheese ripening , during which t he cheese ages and develops it s charact erist ic flavor . Learning how t o select ively act ivat e som e of t hese enzym es could revolut ionize t he cheese m anufact uring process.
The Lact ococcus lact is ssp . lact is genom e has 2 , 365, 589 unit s ( bp) of DNA, w hich cont ain
2 , 310 predict ed genes. About 64 percent of t he genes have assigned roles in t he cell , while 20 percent m at ch ot her hypot het ical genes wit h unknown funct ion . Alm ost 16 percent of t he genes bear no resem blance t o genes from ot her species and are considered t o be unique t o t his bact erium .
The L . lact is genom e cont ains six prophages ( carrying nearly 300 genes or about 14 percent of t he t ot al coding capacit y) and 43 insert ion elem ent s. Sequence dat a also revealed new possibilit ies for ferm ent at ion pat hways and confirm ed t he t ot al lack of genes and enzym es involved in t he TCA cycle alt hough, unexpect edly , cert ain genes necessary for aerobic respirat ion were found encoded in t he genom e.
I t is ant icipat ed t hat underst anding t he physiology and genet ic m ake - up of t his bact erium will prove invaluable for food m anufact urers as well as t he pharm aceut ical indust ry , which is exploring t he capacit y of L. lact is t o serve as a vehicle for delivering drugs and vaccines.
For exam ple, genom ic analysis of Lact ococcus lact is subsp lact is revealed t he presence of several genes t hat encode enzym es involved in t he reduct ion of pyruvat e t o various end- product ot her t han hom olact ic acid, including et hanol, acet ic acid, form ic acid, diacet yl, acet oin and but anediol . Manipulat ion and underst anding of t he regulat ion of t hese genes could defeat or enhance t he synt hesis of t hese end product s leading t o st rain im provem ent in st art er cult ures for cheeses, but t erm ilk , and ot her dairy product s.
Th e pyr u va t e m e t a bolism of La ct ococcu s la ct is. LD H: la ct a t e de h ydr oge n a se ; PD H : pyr u va t e de h ydr oge n a se com ple x ; PFL: pyr u va t e for m a t e - lya se; AD H E:
a ce t a lde h yde de h ydr oge n a se ; AD H A : a lcoh ol de h ydr oge n a se ; PTA : ph osph ot r a n sa ce t yla se ; ACKA: a ce t a t e k in a se, ALS/ I LV B: ca t a bolic a n d a n a bolic
2 - a ce t ola ct a t e syn t h a se; ALD B: a ce t ola ct a t e de ca r box yla se ; BUTA: dia ce t yl r e du ct a se; BUTB: a ce t oin r e du ct a se; N OX : N AD H ox ida se . Olive ir a e t a l. BM C M icr obiology . 5 : 3 9 ( 2 0 0 5 ) .
END OF CHAPTER
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