The aim of this study is to develop bioplastic film from a combination of two biopolymers of same
source, namely banana peel and corn starch. Five banana peel films (BP film) were prepared with
different concentrations of corn starch (1% up to 5%) as co-biopolymer and film without corn
starch acted as a control. The films were carried out with several durability tests and
characterization analyses. Based on the results obtained, the BP film with 4% corn starch gave the
highest tensile strength 34.72 N/m2 compared to other samples. The water absorption test showed
that BP films with 3% corn starch were resistant to water uptake by absorbing water up to 60.65%.
In terms of characterization, spectra of Fourier Transform Infrared Spectroscopy (FTIR) obtained
for BP control film and BP film with 4% corn starch were comparable with most of the peaks were
present. The thermal analysis by differential screening calorimetric (DSC) detected the melting
temperature for both BP control film and BP film with 4% corn respectively at Tonset of 54.41°C
and 67.83°C. Overall, combination of starches from two different sources can be used as an
alternative in producing bioplastics.
Petroleum hydrocarbons remain as the major contaminants that could be found across the world.
Remediation approach through the utilisation of microbes as the bioremediation means widely
recognised due to their outstanding values. As a result, scientific reports on the isolation and
identification of new hydrocarbon-degrading strains were on the rise. Colourimetric-based assays
are one of the fastest methods to identify the capability of hydrocarbon-degrading strains in both
qualitative and quantitative assessment. In this study, the hydrocarbon-degrading potential of
nine bacterial isolates was observed via 2,6-dichlorophenolindophenol (DCPIP) test. Two potent
diesel-utilising isolates show a distinctive tendency to utilise aromatic (ADL15) and aliphatic
(ADL36) hydrocarbons. Both isolates prove to be a good candidate for bioremediation of wide
range of petroleum hydrocarbon components.
Quinolines compounds are toxic pollutants. Their biodegradation by microbes represents a tool
for bioremediation. The growth of Klebsiella penumoniae on 2-methylquinoline shows typical
sigmoidal bacterial growth curves. Since there exists a variety of models for describing the
growth profile of microorganism such as logistic, Gompertz, Richards, Schnute, Baranyi-
Roberts, Von Bertalanffy, Buchanan three-phase and more recently Huang models, the growth
curves exhibit under such conditions would be an excellent study for finding the best model.
The Huang model was chosen as the best model based on statistical tests such as root-meansquare
error (RMSE), adjusted coefficient of determination (R2), bias factor (BF), accuracy
factor (AF) and corrected AICc (Akaike Information Criterion). Novel constants obtained from
the modelling exercise would be used for further secondary modelling.
In this study, a novel glyphosate-degrading shows the ability to reduce molybdenum to
molybdenum blue. The enzyme from this bacterium was partially purified and partially
characterized to ascertain whether the Mo-reducing enzyme from this bacterium shows better or
lower efficiency in reducing molybdenum compared to other Mo-reducing bacterium that only
exhibits a single biotransformation activity. The enzyme was partially purified using ammonium
sulphate fractionation. The Vmax for the electron donating substrate or NADH was at 1.905 nmole
Mo blue/min while the Km was 6.146 mM. The regression coefficient was 0.98. Comparative
assessment with the previously characterized Mo-reducing enzyme from various bacteria showed
that the Mo-reducing enzyme from Burkholderia vietnamiensis strain AQ5-12 showed a lower
enzyme activity.
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.
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.
Heavy metals pollution has become a great threat to the world. Since instrumental methods are
expensive and need skilled technician, a simple and fast method is needed to determine the
presence of heavy metals in the environment. In this work, a preliminary study was carried out
on the applicability of various local plants as a source of protease for the future development of
the inhibitive enzyme assay for heavy-metals. The crude proteases preparation was assayed using
casein as a substrate in conjunction with the Coomassie dye-binding assay. The crude protease
from the kesinai plant was found to be the most potent plant protease. The crude enzyme
exhibited broad temperature and pH ranges for activity and will be developed in the future as a
potential inhibitive assay for heavy metals.
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.
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.
Molybdenum is an emerging pollutant. Bioremediation of this heavy metal is possible by the
mediation of Mo-reducing bacteria. These bacteria contain the Mo-reducing enzymes that can
conver toxic soluble molybdenum into molybdenum blue; a less soluble and less toxic form of the
metal. To date only the enzyme has been purified from only one bacterium. The aim of this study is
to purify the Mo-reducing enzyme from a previously isolated Mo-reducing bacterium Bacillus
pumilus strain Lbna using ammonium sulphate fractionation followed by ion exchange and then
gel filtration. Two clear bands were obtained after the gel filtration step with molecular weights
of 70 and 100 kDa. This indicates that further additional purification methods need to be used
to get a purified fraction. Hence, additional steps of chromatography such as hydroxyapatite or
chromatofocusing techniques can be applied in the future.
Phenolic compounds or phenols are a group of aromatic compounds that comprises a hydroxyl
group (OH) that is directly bonded to an aromatic ring. Phenols are injurious to organisms even
at even low concentrations with many of them are categorized as dangerous pollutants because of
their likely harm to human well-being. This review attempts to discuss the various merits and
demerits of immobilization matrices employed for phenol-degrading microorganisms’
immobilization. One of several key points of cellular immobilization is the capacity to protect
bioremediation agents towards toxic levels of specific toxicants and safeguarding from predatory
microorganisms. However, this shielding course of action should never impede the diffusion of
substrates into the pores of the immobilization structure. In the end the choice of a particular
immobilization method will strongly hinge on aspects of economy, safety and efficacy.
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.
Bioremediation is a new green economic approach in providing solutions for cleaning up
contaminated sites. Phytoremediation uses plants as a tool for remediation purposes. The usage
of plant species offers higher potential solution to remediate heavy metal contaminated sites.
This study aimed on screening potential plant species for phytoremediation of heavy metal
contaminated water. The potential of three aquatic macrophytes species (Eichorrnia crassipes,
Pistia stratiotes and Ipomoea aquatica) for chromium and nickel phytoremediations was tested.
The plants were exposed for 10 days under hydroponic conditions in heavy metal contaminated
water. E. crassipes showed the highest chromium and nickel concentrations in its biomass, 1.60
and 2.40 μg/L respectively. Meanwhile, P. stratiotes had chromium and nickel concentrations
detected at 0.89 and 0.081 μg/L, respectively; chromium and nickel concentrations of I.
aquatica detected were, 0.49 and 0.08 μg/L, respectively. The ability of these plants to
accumulate heavy metals and survived throughout the experiment demonstrates the potential of
these plants to remediate metal-enriched water. Among the three tested aquatic plants, E.
crassipes was proven to be the most suitable plant species that can phytoremediate heavy metal
contaminated water followed by P. stratiotes and I. aquatica.
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 growth of microorganism on substrates, whether toxic or not usually exhibits sigmoidal
pattern. This sigmoidal growth pattern can be modelled using primary models such as Logistic,
modified Gompertz, Richards, Schnute, Baranyi-Roberts, Von Bertalanffy, Buchanan threephase
and Huang. Previously, the modified Gompertz model was chosen to model the growth of
Burkholderia sp. strain Neni-11 on acrylamide, which shows a sigmoidal curve. The modified
Gompertz model relies on the ordinary least squares method, which in turn relies heavily on
several important assumptions, which include that the data does not show autocorrelation. In this
work we perform statistical diagnosis test to test for the presence of autocorrelation using the
Durbin-Watson test and found that the model was adequate and robust as no autocorrelation of
the data was found.
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.
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.
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.
Environmental pollution is one of the major concerns in the 21st century; where billions of tonnes
of harmful chemicals are produced by industries such as petroleum, paints, food, rubber, and
plastic. Phenol and its derivatives infiltrate the ecosystems and have become one of the top major
pollutants worldwide. This review covers the major aspects of immobilization of phenoldegrading
bacteria as a method to improve phenol bioremediation. The use of various forms of
immobilization matrices is discussed along with the advantages and disadvantages of each of the
immobilization matrices especially when environmental usage is warranted. To be used as a
bioremediation tool, the immobilized system must not only be effective, but the matrices must be
non-toxic, non-polluting and if possible non-biodegradable. The mechanical, biological and
chemical stability of the system is paramount for long-term activity as well as price is an
important factor when the very large scale is a concern. The system must also be able to tolerate
high concentration of other toxicants especially heavy metals that form as co-contaminants, and
most immobilized systems are geared towards this last aspect as immobilization provides
protection from other contaminants.
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.