Observations on the effects of copper on the liver proteome of Puntius javanicus based on the
one dimensional PAGE was carried out. The liver was dissected from each fish, which was
separately treated with different concentrations of copper sulfate ranging from 0.1 to 5.0 mg/L.
The livers were extracted and one dimensional PAGE was performed under nonreducing
(native) and reducing (SDS)-PAGE. Several bands were resolved in the native PAGE with
probable candidates for the effect of copper observed showing an increased in the expression
and downregulation strongly associated with increasing copper concentrations. This study
showed that high concentrations of copper significantly alters P. javanicus liver at the proteome
level, and preliminary screening based on one dimensional PAGE is considered rapid and
simple to assess the toxicity effect of copper before more advanced and extensive assesment
with a second dimensional PAGE is carried out.
The volume of contaminated rivers in Malaysia continues to keep rising through the years. The
cost of instrumental monitoring is uneconomical and prohibits schedule monitoring of
contaminants particularly heavy metals. In this work, a rapid enzyme assay utilizing the
molybdenum-reducing enzyme as an inhibitive assay, prepared in crude form from the
molybdenum-reducing bacterium Serratia sp. strain DRY5 has been developed for monitoring
the heavy metals mercury, silver, copper and chromium in contaminated waters in the Juru
Industrial Estate. The crude enzyme extract transformed soluble molybdenum
(phosphomolybdate) into a deep blue solution, which is inhibited by heavy metals such as
mercury, silver, copper and chromium. The IC50 and Limits of Detection (LOD) values for
mercury, copper, silver and cadmium were 0.245, 0.298, 0.367, 0.326, and 0.124, 0.086, 0.088
and 0.094 mg L-1, respectively. The assay is rapid, and can be carried out in less than 10 minutes.
In addition, the assay can be carried out at ambient temperature. The IC50 values for these heavy
metals are more sensitive than several established assays. Water samples from various locations
in the month of November from the Juru Industrial Estate (Penang) were tested for the presence
of heavy metals using the developed assay. Enzyme activity was nearly inhibited for water
samples from several locations. The presence of heavy metals was confirmed instrumentally
using Atomic Emission Spectrometry and a Flow Injection Mercury System. The assay is rapid
and simple and can be used as a first screening method for large scale monitoring of heavy
metals.
Acrylamide is a synthetic monomer that has been classified as toxic and carcinogenic apart
from its diverse application in the industry. Its application is in the formation of
polyacrylamide. Polyacrylamide usage is diverse and is found as herbicide formulation, as soil
treatment agent and in water treatment plants. Deaths and sickness due to the accidental
exposure to acrylamide have been reported while chronic toxicity is also a source of the
problem. This review highlighted the toxic effect of acrylamide to various organisms like
human, animal and plant. This review also discusses on the potential use of biological
technologies to remediate acrylamide pollution in the environment and the degradation
pathways these microorganisms utilize to assimilate acrylamide as a nitrogen, carbon or both as
carbon and nitrogen sources.
Acetylcholinesterase (AChE) is usually used as an inhibitive assay for insecticides. A lesser
known property of AChE is its inhibition by heavy metals. In this work we evaluate an AChE
from brains of striped snakehead (Channa striatus) wastes from aquaculture industry as an
inhibitive assay for heavy metals. We discovered that the AChE was inhibited almost completely
by Hg2+, Ag2+ and Cu2+ during an initial screening. When tested at various concentrations, the
heavy metals exhibited exponential decay type inhibition curves. The calculated IC50 for the
heavy metals Hg2+, Ag2+, Pb2+, Cu2+ and Cr6+ were 0.08432, 0.1008, 0.1255, 0.0871, and 0.1771,
respectively. The IC50 for these heavy metals are comparable and some are lower than the IC50
values from the cholinesterases from previously studied fish. The assay can be carried out in less
than 30 minutes at ambient temperature.
Acetylcholinesterase (AChE) is usually used as an inhibitive assay for insecticides. A lesserknown
property of AChE is its inhibition by heavy metals. In this work, we evaluate an AChE
from brains of Clarias batrachus (catfish) exposed to wastes from aquaculture industry as an
inhibitive assay for heavy metals. We discovered that the AChE was inhibited completely by
Hg2+, Ag2+, Pb2+, Cu2+, Cd2+, Cr6+ and Zn2+ during initial screening. When tested at various
concentrations, the heavy metals exhibited exponential decay type inhibition curves. The
calculated IC50 (mg/L) for the heavy metals Ag2+, Cu2+, Hg2+, Cr6+ and Cd2+ were 0.088, 0.078,
0.071, 0.87 and 0.913, respectively. The IC50 for these heavy metals are comparable, and some
are lower than the IC50 values from the cholinesterases from previously studied fish. The assay
can be carried out in less than 30 minutes at ambient temperature.
In this work we assess the potential of acetylcholinesterase (AChE) from Oreochromis
mossambicus (Toman) as a sensitive test for the presence of insecticides. The partial purification
and characterization of a soluble AChE from Oreochromis mossambicus brain tissues using
affinity chromatography gel (procainamide–Sephacryl S-1000) showed that the partially purified
AChE was most active on acetylthiocholine (ATC) but had low activities on
propionylthiocholine (PTC) and butyrylthiocholine (BTC), indicating that the partially purified
fraction was predominantly AChE. Soluble AChE was partially purified 9.27-fold with a 91.12%
yield. The partially purified AChE displayed the highest activity on ATC at pH 7 and at 30oC
using 0.1 M Tris buffer. The enzyme exhibited Michaelis-Menten kinetic constants, Km, for
ATC, BTC and PTC at 36, 77 and 250 μM, respectively, and the maximum velocities, Vmax, were
18.75, 0.12 and 0.05 μmol/min/mg protein, respectively. Moreover, the AChE from
Oreochromis mossambicus presented comparable sensitivity to carbamates and
organophosphates insecticides than that from Electrophorus electricus and many other fish
AChE by comparing half maximal inhibitory concentration values. Therefore, the enzyme is a
valuable source for insecticides detection in Malaysian waters at lower cost.
Water contamination by herbicides and chelating agents is increasing mainly due to the
increasing agricultural activities. Water contamination by these compounds has become a
concern due to their adverse effects to the environment and humans. Seven sampling sites of
water sources in Selangor and Johor were chosen for the study. Contamination level of
Mecoprop (MCCP), Nitrilotriacetic acid (NTA) and Ethylenediaminetetraacetic acid (EDTA) in
these water body areas was determined by using Gas Chromatography-Electron Capture
Detector (GC-ECD). Our results indicated that water samples of Sungai Melot in Selangor
showed the highest presence of EDTA. MCCP was detected at a high level at Sungai Sarang
Buaya, Johor while NTA showed similar level of concentration at three different sites, Ladang
10, Ladang Sayur and Mardi, Selangor.
The 3D structure of the insecticidal protein Cry1Ba4 produced by B. thuringiensis subsp.
Entomocidus HD-9 was determined using homology modelling. From the model built, we have
been able to identify the possible sites for structure modification by site-directed mutagenesis.
The mutation was introduced at the conserved region of -helix 7 by substituting the
hydrophobic motif that comprises alanine 216, leucine 217 and phenylalanine 218 with arginine.
Wild and mutant Cry1Ba4 genes were cloned into pET200/D-TOPO and expressed in the
expression host. The result suggests that mutant Cry1Ba4 protein was less toxic to the larvae
Plutella xylostella compared to the wild-type. In conclusion, alteration in the structure of
Domain I had left an impact on the toxicity of Cry1Ba4 against P. xylostella.
Most often than not, microorganism’s growth curve is sigmoidal in characteristics.
The modified Gompertz model via nonlinear regression using the least square method
is one of the most popular methods to describe the growth curve. One of the
assumptions of a good model is that the variance of the data must be homogenous
(homoscedasticity). In this work, two statistical diagnostics; the Bartlett and the
Levene’s tests was performed to a modified Gompertz model utilized to model the
growth of the bacterium Burkholderia sp. strain Neni-11 on acrylamide in order to
satisfy the requirement above and found that data conformed to the requirement
indicating the modified Gompertz model is a robust model for modelling the bacterial
growth process.
Contamination of organic xenobiotic pollutants and heavy metals in a contaminated site allows
the use of multiple bacterial degraders or bacteria with the ability to detoxify numerous toxicants
at the same time. A previously isolated SDS- degrading bacterium, Acinetobacter baumannii
strain Serdang 1 was shown to reduce molybdenum to molybdenum-blue. The bacterium works
optimally at pH 6.5, the temperature range between 25 and 34°C with glucose serves as the best
electron donor for molybdate reduction. This bacterium required additional concentration of
phosphate at 5.0 mM and molybdate between 15 and 25 mM. The absorption spectrum of the
molybdenum blue obtained is similar to the molybdenum blue from other earlier reported
molybdate reducing bacteria, as it resembles a reduced phosphomolybdate closely. Ag(i), As(v),
Pb(ii) and Cu(ii) inhibited molybdenum reduction by 57.3, 36.8, 27.7 and 10.9%, respectively, at
1 p.p.m. Acrylamide was efficiently shown to support molybdenum reduction at a lower
efficiency than glucose. Phenol, acrylamide and propionamide could support the growth of this
bacterium independently of molybdenum reduction. This bacterium capability to detoxify several
toxicants is an important tool for bioremediation in the tropical region.
The Q10 value is tied to an increase in the surrounding temperature with an increase in 10 ◦C,
and usually resulted in a doubling of the reaction rate. When this happens, the Q10 value for the
reaction is 2. This value holds true to numerous biological reactions. To date, the Q10 value for
the biodegradation of phenol is almost not reported. The Q10 values can be determined from the
Arrhenius plots. In this study, the growth rate or biodegradation rates in logarithmic value for
the bacterium Pseudomonas sp. AQ5-04 was plotted against 1000/temperature (Kelvin) and the
slope of the Arrhenius curve is the value of the Ea, which was utilized to obtain the Q10. The
value obtained in this work was 1.834, which is slightly lower than the normal range of between
2 and 3 for the biodegradation rates of hydrocarbon in general and shows that this bacterium is a
very efficient phenol-degrading bacterium.
The issue of heavy metal contamination and toxic xenobiotics has become a rapid global
concern. This has ensured that the bioremediation of these toxicants, which are being carried out
using novel microbes. A bacterium with the ability to reduce molybdenum has been isolated
from contaminated soils and identified as Serratia marcescens strain DR.Y10. The bacterium
reduced molybdenum (sodium molybdate) to molybdenum blue (Mo-blue) optimally at pHs of
between 6.0 and 6.5 and temperatures between 30°C and 37°C. Glucose was the best electron
donor for supporting molybdate reduction followed by sucrose, adonitol, mannose, maltose,
mannitol glycerol, salicin, myo-inositol, sorbitol and trehalose in descending order. Other
requirements include a phosphate concentration of 5 mM and a molybdate concentration of
between 10 and 30 mM. The absorption spectrum of the Mo-blue produced was similar to the
previously isolated Mo-reducing bacterium and closely resembles a reduced phosphomolybdate.
Molybdenum reduction was inhibited by Hg (ii), Ag (i), Cu (ii), and Cr (vi) at 78.9, 69.2, 59.5
and 40.1%, respectively. We also screen for the ability of the bacterium to use various organic
xenobiotics such as phenol, acrylamide, nicotinamide, acetamide, iodoacetamide, propionamide,
acetamide, sodium dodecyl sulfate (SDS) and diesel as electron donor sources for aiding
reduction. The bacterium was also able to grow using amides such as acrylamide, propionamide
and acetamide without molybdenum reduction. The unique ability of the bacterium to detoxify
many toxicants is much in demand, making this bacterium a vital means of bioremediation.
2,4-dinitrophenol (2,4-DNP) is utilized in the production of wood preservatives, dyes, and also
as a pesticide. Human acute (short-term) exposure to 2,4-DNP in humans by means of oral
exposure are nausea or vomiting, sweating, headaches, dizziness, and weight reduction. Thus, the
removal of this compound is highly sought. A 2,4-DNP-degrading bacterium (isolate 1) was
isolated from a sample soil from Terengganu. This bacterium (isolate 1) was characterized as a
rod Gram positive, non-sporulated, and non-motile bacterium. The bacterium is oxidase negative
and had catalase positive activity and was able to grow aerobically on 2,4-dinitrophenol as the
sole carbon source. This bacterium showed maximal growth on 2,4-DNP at the temperature
optimum of 30 oC, pH 5.0 and was tolerant to 2,4-DNP concentration of up to 0.5 mM (0.092
g/L). This bacterium prefers to use urea as the nitrogen source in addition to yeast extract for
mineral source and vitamin precursors.
The indiscriminate released of heavy metals and xenobiotics into soils and aquatic bodies
severely alter soil organisms and the ecosystem. The isolation of xenobiotics degrading
microorganisms is cost-effective and naturally pleasant approach. Lately, the toxicological effect
of molybdenum to the spermatogenesis of several organisms has been record. This present study
is aimed at the isolation and characterization of a bacterium capable of converting molybdenum
to the colloidal molybdenum blue. Bacteria characterization was performed in a microplate
format using resting cells. Thus, the reduction process can be employed as a device for
molybdenum bioremediation. The results of the study revealed an optimum reduction at pH
between 6.0 and 6.3 and temperatures of between 25 and 40 oC. Similarly, it was also observed
that a phosphate concentration not greater than 5.0 mM and a sodium molybdate concentration
at 20 mM was required for reduction. Glucose was observed as the best carbon source to support
reduction. Following the scanning of molybdenum blue, it revealed an absorption spectrum
indicating the characteristics of molybdenum blue as a reduced phosphomolybdate. Molybdenum
reduction is inhibited by heavy metals like silver, lead, arsenic and mercury. Furthermore, the
ability of the bacterium (Pseudomonas sp. strain Dr.Y Kertih) to utilize several organic
xenobiotics such as phenol, acrylamide, nicotinamide, acetamide, iodoacetamide, propionamide,
acetamide, sodium dodecyl sulfate (SDS) and diesel as electron donor sources for aiding
reduction or as carbon sources for growth was also examined. Finding showed that none was
capable of aiding molybdenum reduction, however the bacterium was capable of growing on both
diesel and phenol as carbon sources. GC analysis was used to confirmed diesel degradation.
The presence of both heavy metals and organic xenobiotic pollutants in a contaminated site
justifies the application of either a multitude of microbial degraders or microorganisms having
the capacity to detoxify a number of pollutants at the same time. Molybdenum is an essential
heavy metal that is toxic to ruminants at a high level. Ruminants such as cow and goats
experience severe hypocuprosis leading to scouring and death at a concentration as low as
several parts per million. In this study, a molybdenum-reducing bacterium with amide-degrading
capacity has been isolated from contaminated soils. The bacterium, using glucose as the best
electron donor reduces molybdenum in the form of sodium molybdate to molybdenum blue. The
maximal pH reduction occurs between 6.0 and 6.3, and the bacterium showed an excellent
reduction in temperatures between 25 and 40 oC. The reduction was maximal at molybdate
concentrations of between 15 and 25 mM. Molybdenum reduction incidentally was inhibited by
several toxic heavy metals. Other carbon sources including toxic xenobiotics such as amides
were screened for their ability to support molybdate reduction. Of all the amides, only
acrylamide can support molybdenum reduction. The other amides; such as acetamide and
propionamide can support growth. Analysis using phylogenetic analysis resulted in a tentative
identification of the bacterium as Pseudomonas sp. strain 135. This bacterium is essential in
remediating sites contaminated with molybdenum, especially in agricultural soil co-contaminated
with acrylamide, a known soil stabilizer.
Chemical toxins and organic contaminants such as hydrocarbons and dyes are major global
contaminants with countless tones of those chemicals are created yearly with a significant
amount release to the environment. In this work we screen the ability of a molybdenum-reducing
bacterium isolated from contaminated soil to decolorize various azo and triphenyl methane dyes
independent of molybdenum reduction. Biochemical analysis resulted in a tentative identification
of the bacterium as Enterobacter sp. strain Zeid-6. The bacterium was able to decolorize the azo
dye Orange G. The bacterium reduces molybdate to Mo-blue optimally at pH between 5.5 and
8.0 and temperatures of between 30 and 37 oC. Other requirements include a phosphate
concentration of 5 mM and a molybdate concentration of 20 mM. The absorption spectrum of the
Mo-blue produced was similar to previous Mo-reducing bacterium, and closely resembles a
reduced phosphomolybdate. Molybdenum reduction was inhibited by copper, lead, mercury and
silver which showed 36.8, 16.9, 64.9 and 67.6% inhibition to Mo-reducing activity of
Enterobacter sp. strain Zeid-6, respectively. The resultant molybdenum blue spectrum closely
resembles the spectrum of molybdenum blue from the phosphate determination method. The
ability of this bacterium to detoxify molybdenum and decolorize azo dye makes this bacterium
an important tool for bioremediation.
Isolate JR1 was isolated from the polluted textile industry activities site in the Juru Penang area.
This bacterium was characterized as a gram-positive Bacillus bacterium and also gave a
positive biochemical test for catalase test and oxidase test. The isolate JR1 gave a maximum
decolourization of Amaranth dye under static conditions with the rate of decolorization of
98.82%. Seven variables which are pH, temperature (°C), ammonium acetate (g/L), glucose
(g/L), sodium chloride (g/L), yeast (g/L) and dye concentration (ppm) was run by using
Plackett-Burman design for the effective parameter of the decolourization of Amaranth. From
the seven variables, three effective variables which were ammonium acetate, glucose, and dye
concentration were further optimized by using a central composite design. The optimum value
of ammonium acetate concentration at 0.74 g/L, glucose concentration at 3.0 g/L and a dye
concentration at 58.1 ppm gave the highest percentage of decolourization. Thus, this isolate
could provide an alternate solution in removing toxic dyes from environments.
Bacterial based remediation of environmental toxicants is a promising innovative technology
for molybdenum pollution. To date, the enzyme responsible for molybdate reduction to Moblue
from bacteria show that the Michaelis-Menten constants varies by one order of magnitude.
It is important that the constants from newer enzyme sources be characterized so that a
comparison can be made. The aim of this study is to characterize kinetically the enzyme from a
previously isolated Mo-reducing bacterium; Bacillus pumilus strain Lbna. The maximum
activity of this enzyme occurred at pH 5.5 and in between 25 and 35 oC. The Km and Vmax of
NADH were 6.646 mM and 0.057 unit/mg enzyme, while the Km and Vmax of LPPM were 3.399
mM and 0.106 unit/mg enzyme. The results showed that the enzyme activity for Bacillus
pumilus strain Lbna were inhibited by all heavy metals used. Zinc, copper, silver, chromium,
cadmium and mercury all caused more than 50% inhibition to the Mo-reducing enzyme activity
with copper being the most potent with an almost complete inhibition of enzyme activity
observed.
The pollution of heavy metals and toxic xenobiotics has become a central issue worldwide.
Bioremediation of these toxicants are being constantly carried out using novel microbes.
Molybdenum reduction to molybdenum blue is a detoxification process and mathematical
modelling of the reduction process can reveal important parameters such as specific reduction
rate, theoretical maximum reduction and whether reduction at high molybdenum concentration
affected the lag period of reduction. The used of linearization method through the use of natural
logarithm transformation, although popular, is inaccurate and can only give an approximate
value for the sole parameter measured; the specific growth rate. In this work, a variety of
models for such as logistic, Gompertz, Richards, Schnute, Baranyi-Roberts, Von Bertalanffy,
Buchanan three-phase and more recently Huang were utilized for the first time to obtain values
for the above parameters or constants. The modified Gompertz model was the best model in
modelling the Mo-blue production curve from Serratia marcescens strain DR.Y10 based on
statistical tests such as root-mean-square error (RMSE), adjusted coefficient of determination
(R2), bias factor (BF), accuracy factor (AF) and corrected AICc (Akaike Information Criterion).
Parameters obtained from the fitting exercise were maximum Mo-blue production rate (μm), lag
time (l) and maximal Mo-blue production (Ymax) of X (h-1), Y (h) and Z (nmole Mo-blue),
respectively. The application of primary population growth models in modelling the Moblue
production rate from this bacterium has become a successful undertaking. The model
may also be used in other heavy metals detoxification processes. The parameters
constants extracted from this work will be a substantial help for the future development
of further secondary models.
Molybdenum, an emerging pollutant, has being demonstrated recently to be toxic to
spermatogenesis in several animal model systems. Metal mines especially gold mine often use
cyanide and hence isolation of metal-reducing and cyanide-degrading bacteria can be useful for
the bioremediation of these pollutants. Preliminary screening shows that three cyanide-degrading
bacteria were able to reduce molybdenum to molybdenum blue (Mo-blue) when grown on a
molybdate low phosphate minimal salts media. Phylogenetic analyses of the 16S rRNA gene of
the best reducer indicates that it belongs to the Serratia genus. A variety of mathematical models
such as logistic, Gompertz, Richards, Schnute, Baranyi-Roberts, von Bertalanffy, Buchanan
three-phase and Huang were used to model molybdenum reduction, and the best model based on
statistical analysis was modified Gompertz with lowest values for RMSE and AICc, highest
adjusted R2 values, with Bias Factor and Accuracy Factor nearest to unity (1.0). The reduction
constants obtained from the model will be used to carry out secondary modelling to study the
effect of various parameters such as substrate, pH and temperature to molybdenum reduction.