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