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| Articles
by
Noorlidah Abdullah |
Total Records (
5 ) for
Noorlidah Abdullah |
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Mei-Fong Pang
,
Geok-Yuan Annie Tan
,
Noorlidah Abdullah
,
Choon-Weng Lee
and
Ching-Ching Ng
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Culture-independent approach was employed to retrieve
diverse type I and type II polyketide synthase (PKS) ketosynthase (KS)
domains from community DNA extracted from forest topsoil. Type I KS domains
detected were from four phyla which comprised Cyanobacteria, Proteobacteria,
Actinobacteria, Chloroflexi and uncultured bacteria. The type II KS
α domains were derived from four suborders of actinobacteria
in addition to uncultured bacteria. Approximately 25% of the KS domains
were recovered from uncultured bacteria and many sequences of type I KS
were derived from Myxobacteria. BLASTP results showed that the type I
and type II KS domain amino acid sequences were between 52 to 93% identical
to the comparative sequences in the GenBank database. Phylogenetic analysis
for novelty prediction of KS domains showed 14 and 9 novel clades of type
I KS and type II PKS KSα domains, respectively. These
phylogenetically distinct novel clades might represent a new subclass
of KS domains. Present data suggests the possibility of further discovery
of novel genes encoding bioactive compounds which may have medical and
pharmaceutical value. |
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Umaiyal Munusamy
,
Vikineswary Sabaratnam
,
Sekaran Muniandy
,
Noorlidah Abdullah
,
Ashok Pandey
and
E.B.G. Jones
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Four strains of Pycnoporus sanguineus isolated
from Thailand (KUM 60953), Shah Alam (KUM 60954), Endau Rompin (KUM 60955),
Cherating (KUM 60956) and Gombak (KUM 60957) were grown on PDA plates.
Laccase of P. sanguineus was produced using oil palm frond parenchyma
tissue (OPFPt) in solid substrate fermentation (SSF). Strain KUM 60954
produced significant (p = 0) levels of laccase at 2.53 U mL-1
(76 U g-1) followed by KUM 60957 at 1.05 U mL-1
(32 U g-1), KUM 60956 at 0.55 U mL-1 (17 U g-1)
and KUM 60955 at 0.46 U mL-1 (14 U g-1). Meanwhile,
KUM 60953 (reference strain) from Thailand produced 2.44 U mL-1
of laccase (73 U g-1 of OPFPt). Biodegradation of a mixture
of 10 ppm each of phenanthrene, anthracene and pyrene by 30 U mL-1
of laccase in sodium citrate buffer pH 5 was studied. The reaction mixture
was incubated at 40°C and was shaken at 80 rpm for 24 h. Laccase of
KUM 60954 degrades 90% of phenanthrene, 37% of anthracene and 96% of pyrene.
Meanwhile, laccase of KUM 60953 degrades 89% of phenanthrene, 43% of anthracene
and 95% pyrene. Pyrene was rapidly biodegraded followed by phenanthrene
and anthracene. However, a similar pattern of degradation was observed
for both KUM 60953 and KUM 60954. Degraded PAH sample was further tested
for toxicity using Artemia. The untreated PAH caused more than
50% of Artemia death while for the treated PAH no death was observed
indicating that the toxicity level was reduced and possibly no any new
toxic compound was produced during the degradation. |
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Y.S. Low
,
Noorlidah Abdullah
and
S. Vikineswary
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This study was aimed to evaluate the advantages of immobilization
of Pycnoporus sanguineus on Ecomat for mycelial biomass yield,
laccase production and hence, polycyclic aromatic hydrocarbons (PAHs)
degradation. The addition of polycyclic aromatic hydrocarbons standard
mixture increased the mycelial biomass yield of both immobilized and free
mycelia of P. sanguineus with the highest dry weight obtained at
10 days of incubation of 0.46 and 1.88 g, respectively. The immobilized
mycelia culture degraded 88% of phenanthrene, 93% of anthracene and 85%
of pyrene within 20 days. In comparison, free mycelia culture rapidly
degraded 42% of phenanthrene, 92% of anthracene and 87% of pyrene at the
end of 20 days incubation period. The high correlation between the amounts
of polycyclic aromatic hydrocarbons degraded and laccase activity of both
immobilized and free mycelia culture indicated possible involvement of
laccase in polycyclic aromatic hydrocarbons degradation. |
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Umaiyal Munusamy
,
Vikineswary Sabaratnam
,
Sekaran Muniandy
,
Noorlidah Abdullah
,
Ashok Pandey
and
E.B.G. Jones
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Four strains of Pycnoporus sanguineus isolated
from Shah Alam (KUM 60954), Endau Rompin (KUM 60955), Cherating (KUM 60956),
Gombak (KUM 60957) and the standard strain from Thailand (KUM 60953) were
evaluated for their ability to grow on Polycyclic Aromatic Hydrocarbon
(PAH)- and acetonitrile-incorporated Potato Dextrose Agar (PDA). The mycelial
growth was then compared to the growth of P. sanguineus on PAH
and acetonitrile free PDA. All strains tested showed a high tolerance
to PAH up to 25 ppm and 2.5% of acetonitrile. Laccase derived from the
best strains KUM 60954 and KUM 60953 which exhibited higher tolerance
to both PAH and acetonitrile was further characterised. The activity was
maximum for both strains at pH 5.0 and 40 °C. Laccase from both strains
was stable over a wide range of pH (3-5) and at temperatures below 60 °C.
Laccase was stored as a concentrate or as a lyophilised powder to minimise
the degradation of enzyme activity during storage. The laccase activity
in the extract remained a high activity up to four months at optimum pH
5.0 and at both 0 and 4 °C. Further laccase was also stable up to 24
h at 40 °C when mixed with 1% of acetonitrile. |
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Jaime Y.S. Low
,
Noorlidah Abdullah
and
S. Vikineswary
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The ability of white rot fungus Pycnoporus sanguineus
to colonize support materials and subsequently produce laccase and degradation
of Polycyclic Aromatic Hydrocarbons (PAHs) was compared with free mycelia
culture. Natural support, Ecomat, was found to be the best support material
for P. sanguineus for mycelial colonization and laccase activity
with maximum activity of 39 nkat mL-1 on day nine of incubation.
Coconut husk and grey scouring sponge produces maximum laccase activity
of 9.17 and 6.67 nkat mL-1, respectively on day 15. Pycnoporus
sanguineus immobilized culture exhibited higher PAHs degradation efficiency
compared to the free mycelia culture during the 20 days of incubation.
The immobilized mycelia culture degraded 88% of phenanthrene, 93% of anthracene
and 85% of pyrene within 20 days. The good correlation between the amount
of PAHs degraded and laccase activity produced in the immobilization medium
indicated that laccase was solely responsible for degradation of the three
PAHs tested. In comparison, free mycelia culture rapidly degraded 42%
of phenanthrene, 92% of anthracene and 87% of pyrene at the cessation
of incubation. However, poor correlation between the amount of PAHs degraded
and laccase activity measured in the free cell culture was obtained. This
suggested that intracellular enzymes could be involved in PAHs degradation
in the free cell culture. |
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