L-forms

L-forms

[named for Lister Institute]
Spontaneous variants of bacteria that replicate as filterable spheres with defective or absent cell walls. They are filterable because of their flexibility rather than their size. Stable forms may grow for an indefinite time in a wall-less state. Organisms of the unstable form are capable of regenerating their cell walls and reverting to their antecedent bacterial form. The ability of L-forms to cause disease is unknown.
Synonym: L-phase variants
References in periodicals archive ?
- Develop better methods for detecting L-forms in wastewater;
- Identify gene expression targets that promote/repress the L-form state and identify specific locations in WTPs where L-forms can be selectively destroyed; and
In the 1950s, German researchers observed a strange bacterial form in activated sludge (AS) in WTPs, called L-form bacteria.
It is a development from previous work done in the Errington Lab on bacterial variants - called L-forms - which lack a cell wall and can grow if they have some protection, which human tissue allows.
"Although L-forms are much more fragile than walled cells, because they are completely resistant to penicillins and related antibiotics, they may be contributing substantially to problems of persistence or recurrence of infection, which is a frequent clinical problem.
The set of all l-forms, denoted by [[LAMBDA].sup.l] = [[LAMBDA].sup.l]([R.sup.n]), is a l-vector, spanned by exterior products [mathematical expression not reproducible], for all ordered l-tuples I = ([i.sub.1], [i.sub.2], ..., [i.sub.l]), 1 [less than or equal to] [i.sub.1] < ...
From [26], the l-form [u.sub.M] [member of] [L.sup.P](M, [[LAMBDA].sup.l]) is defined by [u.sub.M] = (1/[mu](M)) [[integral].sub.M] u(y)dy if l = 0 and [u.sub.M] = d(Tu) if l = 1, ..., n, 1 [less than or equal to] p [less than or equal to] [infinity].
"In the biofilm unit, which is a colony of spirochetes, the spiral form is often lost and is replaced by cystic forms, granular dot forms [that contain Borrelia DNA], or L-forms," says MacDonald.
Armstrong said their method is very selective at separating out the D- and L-forms. The study findings are being submitted for presentation at a national scientific research conference and for publication in a peer reviewed journal.
We analyzed the data of Table II to compare these two alternatives-the more traditional A or A-W forms with the two L-forms (L-A and A-L).
In our view, L-forms (here, the L-A and A-L forms; more generally, any form that separates developers from maintainers) offer certain important advantages for the contemporary IS organization.
Objective: Despite the clear importance and multiple functions of the bacterial cell wall, many bacteria appearto be able to switch into a cell wall deficient or L-form state.