This review paper briefly explains the meaning and characteristics of endocrine disrupting compounds (EDCs). EDCs comprise various types of natural and synthetic chemical compounds that can impede the reproductive action of the endocrine system in animals and humans. Further discussion is on bisphenol A (BPA), one of the examples of EDCs that is extensively used in industries nowadays. It acts as a monomer, which is desired in the production of polycarbonate plastics and epoxy resins. BPA later ends up in environmental compartments (air, water, sediment). In spite of this, BPA is not categorized as a persistent compound and it will be degraded either by photolysis or bacteria. It can only exist between three and five days in the environment. The concentration of BPA varies in different locations depending on the temperature, pH, source and time of sampling. BPA has been frequently debated due to its toxicity and carcinogenicity towards animals and humans. This paper also explains several extraction procedures and analytical methods concerning how to identify BPA in either aqueous or solid samples. However, an additional review is needed in respect of how to handle, reduce the level of BPA in the environment and understand the details concerning the existence of BPA.
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.
Commercialisation of glyphosate [N-(phosphonomethyl)glycine] in the early 1970s has left a big leap in the agriculture sector. This is due to its effectiveness in controlling a wide range of weeds. Glyphosate translocates well in plants. In addition, with added surfactant in its formulae, it can also be used in wet conditions. Its ability to kill weeds by targeting the 5-enolpyruvyl-shikimate-3-phosphate synthase (EPSPS) makes no competing herbicide analogs in its class. Considering its cost effectiveness, only small amount is needed to cover a large sector in agricultural land. The most important aspect in the success of glyphosate is the introduction of transgenic, glyphosate-resistant crops in 1996. However, glyphosate is not an environmental friendly herbicide. This systematic herbicide has raised environmental concern due to its excessive use in agriculture. Studies have shown traces of glyphosate found in drinking water. Meanwhile, it's rapid binding on soil particles possesses adverse effect to soil organisms. Glyphosate degradation in soil usually carried out by microbial activity. Microbes’ capable utilising glyphosate mainly as phosphate source. However, the activity of C-P lyase in breaking down glyphosate have not clearly understood. This review presents a collective summary on the understanding on how glyphosate works and its environmental fate.
Molybdenum is reported to be very toxic to ruminants and shows evidence of spermatogenesis
toxicity in animals and insects. Hence, its removal is important. In this study, we report on the
first isolation of molybdenum-reducing bacterium from agricultural soil. The bacterium reduces
hexavalent molybdenum (sodium molybdate) to molybdenum blue (Mo-blue); a colloidal
product, which can be trapped and removed from solution. Phylogenetic analysis resulted in a
tentative identification of the bacterium as Serratia sp. strain MIE2. The optimum conditions for
Mo-blue production using the normal one-variable-at-a-time (OVAT) approach were 10 mM of
sodium molybdate, pH 6.0, a temperature of 35°C, ammonium sulphate at 10 g/L as the nitrogen
source and sucrose concentrations of between 30-50 g/L as the carbon source and electron donor
for molybdate. Studies on the effects of pesticides and solvents on Mo-blue production showed
that Mo-blue production from whole cells was relatively more affected by these xenobiotics
compared to the crude enzyme. Nevertheless, the strain was resistant to most of the xenobiotics
tested. Based on the strain MIE characteristics, the bacterium will be a suitable candidate for the
remediation of aquatic bodies and agricultural soils contaminated with molybdenum.
The conversion of hexavalent molybdenum (Mo (VI)) to Mo-blue is a bioremediation technique
which reduces the toxicity of molybdenum to a less toxic form by bacteria. The aim of this study
is to determine the optimum conditions of significant parameters or variables that affect the
reduction of Mo (VI) to Mo-blue by the local isolate identified as Serratia sp. strain MIE2.
Response Surface Methodology (RSM) was used in this study to optimize the reduction process
using Central Composite Design (CCD) as an optimization matrix. The optimum conditions
predicted by RSM using the desirability function for the reduction process were 20 mM
molybdate concentration, 3.95 mM phosphate, 6.25 pH and 25 g/L glucose and Mo-blue
production occurred at the absorbance value of 20.5 at 865 nm. The validation of the predicted
optimum points showed the Mo-blue production occurred at the absorbance value of 21.85 with
a deviation around 6.6 % from the RSM predicted value.
The increase of anthropogenic activities and growth of technology in Antarctica is fuelled by the high demand for petroleum hydrocarbons needed for daily activities. Oil and fuel spills that occur during explorations have caused hydrocarbon pollution in this region, prompting concern for the environment by polar communities and the larger world community. Crude oil and petroleum hydrocarbon products contain a wide variety of lethal components with high toxicity and low biodegradability. Hydrocarbon persistence in the Antarctic environment only worsens the issues stemming from environmental pollution as they can be long-term. Numerous efforts to lower the contamination level caused by these pollutants have been conducted mainly in bioremediation, an economical and degrading-wise method. Bioremediation mainly functions on conversion of complex toxic compounds to simpler organic compounds due to the consumption of hydrocarbons by microorganisms as their energy source. This review presents a summary of the collective understanding on bioremediation of petroleum hydrocarbons by microorganisms indigenous to the Antarctic region from past decades to current knowledge.
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.
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.
Oil spill introduces hydrocarbons into the marine environment and forms oil slicks, which aggregate with other debris to form tarballs. Tarballs are composed of toxic hydrocarbons, which persist in the environment, causing economic and ecological damages. This work studied the isolation and optimization of diesel-oil biodegradation by an indigenous bacterium, identified by 16S rRNA gene sequence analysis, in tarball. An experimental methodology using a Taguchi orthogonal array was applied to optimize the effects of diesel concentration, salinity, nitrate concentration, pH, temperature, agitation speed and time. An isolated bacterium identified as Cellulosimicrobium cellulans removed 88.4% of diesel oil under optimized conditions, where initial diesel-oil concentration was 5% (v/v), NaCl concentration was 20 gL-1 and NH4NO3 concentration was 2 gL-1 in Minimal Salt Media at pH 7, 40oC and 100 revolutions per minute for 5 days. Tarballs harbor hydrocarbon-degrading C. cellulans that can be used under optimized conditions to design an effective oil spill bioremediation technique for mitigating oil pollution.