Agriculture Reference
In-Depth Information
Table 6.1
Different habitat and varying isolation methods for actinomycetes
Habitat
Actinomycete genus isolated
Cultivated field
Cultivated paddy field
Plant matter
Pasture
Lake sediment
Mangrove rhizosphere soil
Tea field soil
Desert soil, marine sediment,
seawater, and activated sludge
Streptomyces
Micromonospora
Microbispora
Micromonospora
Micromonospora
Actinobacteria
Acidophilic and acid tolerant actinomycetes
Pretreatment
Yeast extract (6 %, 20 min)
Enrichment of actinomycetes
Heating (100
C, 1 h)
Streptosporangium, Microbispora
,
Microtetraspora
Phenol (1.0-1.5 %, 30 min)
Dactylosporangium
, Microbispora,
Microtetraspora
Pre-culture with CaCO
3
Enrichment of actinomycetes
Chemotactic method
(KCl,
ɣ
-collidin, xylose)
Motile actinomycetes, actinomycetes,
Dactylosporangium
Medium for isolation
Addition of antibiotics
Novobiocin
Actinoplanes
,
Kitasatospora
Tunicamycin
Micromonospora
Rifampicin
Actinomadura
Chlortetracycline
Nocardia
Macrolide or aminoglycoside
Macrolide or aminoglycoside producer
Addition of humic acid
Rare actinomycetes
Addition of proline
Enrichment of actinomycetes
Gellan gum (substitute for agar)
Actinobispora
Conditions for isolation
High temperature
Thermophilic actinomycetes
Adapted from Takahashi and Omura (
2003
)
to avoid the emergence of bacterial and fungal contaminants. For this, soil samples
are collected bulked, mixed, and allowed to dry heating (at 45
C for 2 h or 50
C
for 10 min or 60
C for 30 min) (Goodfellow
1971
). The isolation medium is also
suspended with antibacterial (penicillin 25 mg/ml) or antifungal (nystatin 0.1 % or
cycloheximide 50 mg/ml) agents (Balagurunathan and Radhakrishnan
2007
).
A 0.1 ml of serially diluted (Nonomura and Ohara
1969
) soil sample is spread
plated onto different actinomycete isolation media, such as casein starch agar, the
Czapek agar, and the oatmeal agar, and incubated at 28
C for 15-30 days. The
resulting colonies are then picked and identified using cultural, morphological
(Pridham and Tresner
1974
; Nonomura
1989
; Sabaou et al.
1998
), and physiolog-
ical (Nonomura and Ohara
1969
; Goodfellow
1971
) characteristics. The actinomy-
cetes are then identified to species level using fatty acid analysis, mol (%) G+ C
contents, DNA-DNA hybridization, and 16S rRNA sequencing.
