Kribbella
Authors: Evtushenko Lyudmila I. , Krausova Valentina I. 
Published: August 2015

Krib.bel'la. N.L. fem. dim. n.
Kribbella
arbitrary name formed from the acronym of the Korea Research Institute of Bioscience and Biotechnology,
KRIBB
, where taxonomic studies of this taxon were performed.

Actinobacteria / Actinobacteria / Propionibacteriales / Nocardioidaceae / Kribbella

Extensively branched vegetative (substrate) hyphae, mostly ~0.4–0.7 μm in diameter
, growing on the surface of, and penetrating, agar media.
Aerial hyphae are typically produced
on suitable agar media. Both the substrate and aerial
hyphae usually undergo various degrees of fragmentation
eventually
resulting in irregular rod‐shaped to coccoid, nonmotile, elements
. Short chains of well‐to‐poorly differentiated conidia may occur on aerial hyphae. Bud‐like cells, apical swellings, and cell conglomerates may be produced by the substrate mycelium. No endospores are formed.
Colonies are pasty to soft‐leathery
, often with lichenous shape and usually no distinct coloration. Diffusible pigments are usually not produced, except for melanoid pigments characteristic of some species.
Gram‐stain‐positive
, but may be variable. Non‐acid‐fast.
Chemoorganotrophs, having a respiratory type of metabolism
, with a potential for mixotrophy and metabolic flexibility.
Grow well under aerobic conditions
on standard laboratory media, including the chemically defined (synthetic) media. Some species show also weak growth under anaerobic conditions. Catalase‐positive. Oxidase test reaction intensity varies with species. Utilize a wide range of carbon and nitrogen sources and possess a significant spectrum of hydrolytic activities. Mesophilic, optimal growth temperature is ~28–30°C; the lower and higher growth temperatures reported for different species are 8°C and 45°C. Usually non‐halophilic and prefer a neutral to mildly alkaline pH; some species grow at initial pH values of 10 and slightly below 5.0.

The cell‐wall peptidoglycan contains
LL
‐diaminopimelic acid

, along with alanine, glutamic acid, and glycine. The muramic acid residue of the peptidoglycan is

N

‐
acetylated
. The
main secondary cell‐wall polymer is teichuronic or teichulosonic acid
. Menaquinones are the sole respiratory quinones detected; the tetrahydrogenated menaquinone with nine isoprene units [

MK‐9(H
4
)] is the major component. The saturated iso‐ and anteiso branched acids (C
15:0

anteiso,

C
16:0

iso,

and C
15:0

iso)
are the main
cellular fatty acids, with

C
15:0

anteiso usually contributing a maximal proportion. Monounsaturated iso‐branched, saturated 9‐methyl branched fatty acids typically occur and may constitute significant amounts. Other fatty acids, including 2‐hydroxy and 10‐methyl branched acids may occur in minor or trace quantities. Mycolates are absent.
The diagnostic component of the polar lipid patterns is phosphatidylcholine
(PC); additional principal polar lipids reported are diphosphatidylglycerol (DPG), phosphatidylglycerol (PG), and phosphatidylinositol (PI).

DNA G
+
C content
(
mol
%): 67–71.3 (
T
m
; HPLC).

Type species
:
Kribbella flavida
Park, Yoon, Shin, Suzuki, Kudo, Seino, Kim, Lee and Lee 1999, 750
VP*
.