Potential Degradation and Kinetics of Melanoidin by Using Laccase from White Rot Fungus

This study was attempted to use laccase extracted from white rot fungus to remove melanoidin in the ethanol production wastewater. The isolated fungus producing the highest laccase was identified as Megaspororia sp. The highest degradation efficiencies of the purified and crude laccases were 48.00% and 44.60%, respectively. Both degradation kinetics well fit Michaelis-Menten model. The Michaelis constant (Km) and maximum rate of reaction (Vmax) were 0.82% melanoidin and 0.0045% melanoidin h-1 for the degradation by the purified laccase and 0.71% melanoidin and 0.0037% melanoidin h-1 for the degradation by the crude laccase. Turnover number (Kcat) of purified and crude laccases were 0.00023 and 0.00019% melanoidin U-1 h-1, respectively. Catalytic efficiency (Kcat/Km) of purified and crude laccases were 0.00028 and 0.00027 U-1 h-1, respectively. The affinity of the crude laccase was slightly higher because of its non-specificity. Kcat and Kcat/Km of the purified laccase were higher than the crude laccase. Proposed potential degradation result showed that laccase could oxidize CH3, carbonyl groups, haloalkanes (C–H), C–O and C–N bondings which probably caused decolorization of melanoidin in wastewater. Thus, the purified and crude laccases can be used to decolorize melanoidin-containing wastewater from ethanol industries. As the attempt to use purified laccase consumed times and costs especially in purification steps, the crude laccase can be used to degrade color of melanoidin in wastewater with only 3.4% lower than the purified laccase

Natural carriers in bioremediation: a review

Bioremediation of contaminated groundwater or soil is currently the cheapest and the least harmful method of removing xenobiotics from the environment. Immobilization of microorganisms capable of degrading specific contaminants significantly promotes bioremediation processes, reduces their costs, and also allows for the multiple use of biocatalysts. Among the developed methods of immobilization, adsorption on the surface is the most common method in bioremediation, due to the simplicity of the procedure and its non-toxicity. The choice of carrier is an essential element for successful bioremediation. It is also important to consider the type of process (in situ or ex situ), type of pollution, and properties of immobilized microorganisms. For these reasons, the article summarizes recent scientific reports about the use of natural carriers in bioremediation, including efficiency, the impact of the carrier on microorganisms and contamination, and the nature of the conducted research

Organophosphate pesticide exposure and dialkyl phosphate urinary metabolites among chili farmers in Northeastern Thailand

Background. Chlorpyrifos and profenofos are organophosphate pesticides (OPPs), we studied exposure and urinary metabolites in an agricultural area in the northeastern of Thailand during the chili-growing season (March - April) in 2012. Objective. This study was designed to assess pesticide exposure concentration through dermal and inhalation pathways and to find and depict a relationship between urinary metabolites and means of exposure. Materials and methods. To estimate the pesticides exposure concentration, dermal wipes (hand, face, and feet), dermal patches and air samples were collected from 38 chili farmers. The morning void of pre and post application urine samples was an indicator of biological monitoring in the study which derived from 39 chili farmers. Results. Chlorpyrifos and profenofos residues were detected on dermal patches, face wipes, and hand wipe samples, while no significant residues were found on the feet. Using a personal air sampling technique, all air samples detected pesticide residues. However, significant correlation between dermal pesticide exposure concentration and inhalation was not found (p>0.05). For urinary metabolite levels, there was a relationship between the first pre application morning void and post application morning void (p<0.05); similar to the association between the first pre application morning void and the second post application morning void (p<0.05). The main relationship between pesticide exposure and urinary metabolite was found to have been relevant to dermal exposure (r= 0.405; p<0.05). Conclusions. The results of this study could suggested that public health education training programs, including the use of appropriate personal protective equipment (PPE), should be offered for the chili growing farmers in order to improve their ability to properly use pesticides.Wprowadzenie. Chlorpiryfos i profenofos należą do pestycydów fosforoorganicznych (OPPs) stosowanych w rolnictwie, dlatego narażenie na te związki badano w północnowschodniej Tajlandii w okresie uprawy chili (marzec – kwiecień) w 2012 roku. Cel. Celem badania była ocena narażenia na pestycydy przez skórę i drogi oddechowe oraz zbadanie zależności pomiędzy stężeniami metabolitów w moczu a drogą narażenia. Materiał i metoda. Do oceny wielkości narażenia wykorzystano wymazy z rąk, twarzy i stóp i naskórne plastry absorpcyjne oraz próbki powietrza pobierane za pomocą indywidualnych próbników u 39 rolników uprawiających chili. Wyniki. Pozostałości chlorpiryfosu i profenofosu stwierdzano na plastrach absorpcyjnych, wymazach z twarzy i rąk, podczas gdy w wymazach ze stóp nie stwierdzano znaczących ilości tych pestycydów. We wszystkich próbkach powietrza stwierdzono obecność pestycydów. Jednakże, nie wykazano znaczącej korelacji pomiędzy wielkością narażenia przez skórę i drogi oddechowe (p>0.05). W przypadku poziomów metabolitów w moczu, wykazano zależność pomiędzy poziomami metabolitów w moczu przed i po pierwszym zabiegu wykonywanym rano (p<0.05). Zależność pomiędzy narażeniem na pestycydy a stwierdzanymi metabolitami w moczu wynikała z narażenia przez skórę (r= 0.405; p<0.05). Wnioski. Wyniki niniejszych badań mogą sugerować potrzebę wprowadzenia programów edukacyjnych z zakresu zdrowia publicznego, uwzględniających stosowanie przez hodowców chili odpowiedniego sprzętu ochrony osobistej, w celu poprawy możliwości właściwego stosowania pestycydów