full issue - Association of Biotechnology and Pharmacy

Current Trends in Biotechnology and Pharmacy
Vol. 5 (3) 1282-1297 July 2011, ISSN 0973-8916 (Print), 2230-7303 (Online)
1288
used in the identification were listed in materials
and methods, results of which are given in Table
2.
The genus Nocardioides is easily
differentiated from all other actinomycetes on
the basis of the diaminopimelic acid type in the
cell wall peptidoglycan, menaquinone profile,
and the cellular fatty acid profile (19,20).
The genus Nocardioides is one of a few
genera that have LL-2,6-diaminopimelic acid
(LL-DAP) as the diagnostic diamino acid in the
cell wall peptidoglycan layer(21). This feature,
together with glycine in the cell wall
peptidoglycan, indicates that this genus is wall
chemotype I (22). This chemical marker
distinguishes the genus Nocardioides from many
other actinomycetes genera that possess other
types of diamino acids in the cell wall
peptidoglycan.
Regarding the bioactivities of the
Nocardioides spp., only a few Nocardioides
strains were found to produce antibiotics
(23,24,25). Strain ATCC 39419, which produced
a novel anti-tumor antibiotic, sandramycin, was
originally assigned to Nocardioides (26) but has
later been classified as a member of a new genus
Kribbella (27).
However, to our knowledge, this is the first
study to investigate the ability of a Nocardioides
sp. to produce antibiotics in detail; regarding the
physiological parameters that affect the
production followed by an attempt to isolate and
identify the active compound(s).
Cultivation parameters : Since antibiotics are
secondary metabolites synthesized by pathways,
which are often connected and influenced by
primary metabolism, thus, frequently an
intermediate metabolite from primary
metabolism serves as precursor for the
biosynthesis of the antibiotic. Therefore, the
composition of the culture medium, closely
connected with the metabolic capacities of the
producing organism, greatly influences the
biosynthesis of antibiotics. Changes in the nature
and concentration of carbon and nitrogen
sources, phosphorus concentration and trace
elements have been reported to affect antibiotic
biosynthesis in different organisms. Results (Fig.
1) showed that activity and growth gradually
increased with increasing the incubation period
till the activity reached maximum after 7 days
Fig. 1. Effect of different fermentation periods on
anticandidal activity of Nocardioides luteus
of incubation then it began to decline with time
while the growth nearly remained constant after
7 days. These results revealed that the
anticandidal metabolite was early produced and
reached maximum at the stationary phase of
growth. The cessation of growth in the stationary
phase is most commonly caused by the
exhaustion of the essential nutrients of the
medium as well as the accumulation of
undesirable metabolites. Similarly, the optimal
incubation period required for maximum growth
and antibiotic yields by Streptomyces sp. 201 was
six days (28). On the other hand, the highest
biomass and antibiotic production of
Streptomyces sp. KEH23 is observed after 96 h
of incubation. However, after 108 h, the diameter
of the inhibition zones dropped gradually (29).
Studies on the production of actinomycin by Nocardioides luteus