The rise in pollution cases globally is expected to increase in line with industrialization.
Monitoring activities for pollutants have been hampered by the astronomical costs of
instrumental-based approach. This has resulted in the intense research on low cost
biomonitoring systems using enzymes, organisms including microorganisms. Only positive
samples are sent for instrumental analysis; dramatically cutting the cost of instrumental
analysis. This review attempts to outline and give due recognition to several selected bioassay
systems that have been tested for their applicability using polluted water samples as a routine
first line-of-defense. This includes small aquatic organisms-based assays, enzymes especially
proteases and bacterial-based systems using respiratory dye or luminescence systems as a
method for toxicant detection.
Centella asiatica, a weakly aromatic plant that flourishes in wet tropical and sub-tropical areas as
a medicinal species since ancient times. It contained important terpenoids that impart important
medicinal values. Currently, studies on the terpenoid content of various Centella asiatica
phenotypes have shown not only variable content but variable growth rates of different
phenotypes that can affect future selection of phenotypes. The use of mathematical growth
modelling can reveal important growth constants and discriminate between faster and slower
growth phenotypes. Two Centella asiatica phenotypes from South Africa is modelled using the
modified Gompertz model and the results showed that the C. asiatica Type-1 exhibited a faster
growth rates and a shorter lag period at 0.152 day-1 and 2.313 day than another phenotype; C.
asiatica Type 2 with a growth rate and a lag period of 0.067 day-1 and 3.363 day, respectively.
The data indicates that different phenotypes of C. asiatica can have different growth rates and
lag period and this can be important for selection of phenotypes to be used as the best bioactive
peptides producer.
One of the most important preliminary investigation of callus attributes is the growth
characteristics. Most often than not, callus growth curve is sigmoidal in characteristics. In this
work, we model callus growth from the seedling of Jatropha curcas L. according to the
modified Gompertz model from published literature to acquire essential growth constants.
These growth constants can be obtained with better precision using model such as the modified
Gompertz. Parameters obtained from the fitting exercise were maximum callus growth rate
(μm), lag time (l) and maximal callus production (Ymax) of 0.193 d-1, 2.91 days and 0.38 g
callus/25 mL culture, respectively. Growth parameter constants extracted from the modelling
exercise will be helpful for additional secondary modelling implicating the consequence of
media conditions as well as other factors on the growth of callus from this plant.
The mistletoe fig (Ficus deltoidea) is frequently found in several areas of the world, and primarily functions as houseplant or an ornamental shrub. The plant is discovered indigenous generally in Asia tropical region for example Indonesia, Philippines, Malaysia, and Thailand. Scientific studies on the effect of plant growth regulators on cells production from this plant are vital as optimization of cells production may result in effective production of secondary products characterization and output. The growth of cell suspension cultures from this plant shows sigmoidal property. In this work, we model the effect of the plant growth regulator 2,4-dichlorophenoxyacetic acid (2,4-D) on the growth kinetics of the cells from this plant according to the modified Gompertz model. The coefficient of determination showed good agreement between experimental and predicted data with values ranging from 0.97-0.98. The results showed that 2,4-D at 2 mg/L was optimal for achieving the highest cells growth rate. It is anticipated that the growth parameter constants extracted from the modelling exercise will be helpful in the future for additional secondary modelling on the effect of media conditions as well as other factors on cells growth.
Ficus deltoidea (or commonly known as mistletoe fig) in various parts of the world mainly
serves as an ornamental shrub or houseplant and found native mainly in Asia tropical region,
for example, Malaysia, Indonesia, Philippines and Thailand. Studies on the effect of plant
growth regulators on cells production from this plant is important as optimization of cells
production can lead to efficient production of secondary products characterization and
production. An important aspect of the sigmoidal cells growth curve is the growth parameters.
In this work, we model the effect of picloram (4-amino-3,5,6-trichloropicolinic acid) on the
growth kinetics of the cell suspension cultures of Ficus deltoidea according to the modified
Gompertz model. The adjusted coefficient of determination showed good agreement between
experimental and predicted data with values ranging from 0.97-0.99. Parameters obtained from
the fitting exercise were maximum cells growth rate (μm), lag time (l) and maximal cells
production (Ymax). The results showed that picloram at concentrations of 3 mg/L and above
were optimal for giving the highest cells growth rate measured as PCV (packed cell volume).
The parameter growth rate obtained from the modelling exercise will be helpful for additional
secondary modelling implicating the consequence of media conditions as well as other factors
on the effect of picloram on the growth rate of cell suspension from this plant.
In this work, a temporal monitoring work for heavy metals from an effluent discharge point in
the Juru Industrial Estate was carried out using the protease extracted from garlic (Allium
sativum) as the principal bioassay system. casein-Coomassie-dye binding assay method has
utilized this purpose. The periodic sampling results for one day of a location in the Juru
Industrial Estate showed temporal variation of copper concentration coinciding with garlic
protease inhibition with the highest concentrations of copper occurring between 12.00 and 16.00
hours of between 3 and 3.5 mg/L copper. The crude proteases extracted from Allium sativum
successfully detect temporal variation of copper form this location. In conclusion, this assay
method has the potential to be a rapid, sensitive, and economic inhibitive assay for the largescale
biomonitoring works for the heavy metal copper from this area.
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 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.
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.