Isolation and culture medium optimisation using one-factor-at-time and response surface methodology on the biodegradation of the azo-dye amaranth

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

Environmental Fate and Degradation of Glyphosate in Soil

oai:ojs1.pjsrr.upm.edu.my:article/124Commercialisation 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

Partial purification and characterization of the molybdenum-reducing enzyme from the glyphosate-degrading Burkholderia vietnamiensis strain AQ5-12

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

Modelling the effect of heavy metal on the growth rate of an SDS-degrading pseudomonas sp. strain DRY15 from antarctic soil

The SDS-degrading bacterium Pseudomonas sp. strain DRY15 was strongly inhibited by heavy metals especially mercury. Growth of the SDS-degrading bacterium at various concentrations of mercury shows a sigmoidal pattern with lag periods ranging from 7 to 10 h. As the concentration of mercury was increased, the overall growth was inhibited with 1.0 g/L causing an almost cessation of bacterial growth. The modified Gompertz model was utilized to obtain growth rates at different concentrations of mercury. The growth rates obtained from the modified Gompertz model was then modelled according to the modified Han-Levenspiel, Wang, Liu, modified Andrews, the Amor and Shukor models. Out of the five models, only the Shukor, Wang, modified Han-Levenspiel and the Liu models were able to fit the curve, whilst the modified Andrews and Amor models were unable to fit the curves. The best model was Shukor based on the lowest values for RMSE and AICc, highest adjusted correlation coefficient (adR2) and values of AF and BF closest to unity. The parameters obtained from the Shukor model, which are Sm, max and n which represent critical heavy metal ion concentration (mg/L), maximum growth rate (h-1) and empirical constant values were 6.0 (95%, confidence interval from 5.87 to 6.14), 0.09 (95%, confidence interval of 0.086 to 0.096) and 4.2 (95%, confidence interval from 3.1 to 5.2), respectively

Optimisation of culture composition for glyphosate degradation by Burkholderia vietnamiensis strain AQ5-12

The herbicide glyphosate is often used to control weeds in agricultural lands. However, despite its ability to effectively kill weeds at low cost, health problems are still reported due to its toxicity level. The removal of glyphosate from the environment is usually done by microbiological process since chemical process of degradation is ineffective due to the presence of highly stable bonds. Therefore, finding glyphosate-degrading microorganisms in the soil of interest is crucial to remediate this glyphosate. Burkholderia vietnamiensis strain AQ5-12 was found to have glyphosate-degrading ability. Optimisation of biodegradation condition was carried out utilising one factor at a time (OFAT) and response surface methodology (RSM). Five parameters including carbon and nitrogen source, pH, temperature and glyphosate concentration were optimised. Based on OFAT result, glyphosate degradation was observed to be optimum at fructose concentration of 6, 0.5 g/L ammonia sulphate, pH 6.5, temperature of 32 °C and glyphosate concentration at 100 ppm. Meanwhile, RSM resulted in a better degradation with 92.32% of 100 ppm glyphosate compared to OFAT. The bacterium was seen to tolerate up to 500 ppm glyphosate while increasing concentration results in reduced degradation and bacterial growth rate

Isolation and characterisation of glyphosate-degrading bacteria isolated from local soils in Malaysia

Glyphosate (N-(phosphonomethyl)glycine) is a herbicide that is used to kill broadleaf weeds and grass, which was developed by the Monsanto company in the early 1970s. However, excessive usage of glyphosate in the agricultural field has led to soil accumulation of the pesticides causing various adverse effects. Due to the concern on its toxicity, an alternative way to ease its effect is through bioremediation, which exploits the ability of microorganisms to degrade harmful toxic substances into less toxic forms. Seven different microbial strains were isolated from glyphosate-contaminated sites in Malaysia. These strains were able to grow in a medium containing glyphosate as the sole phosphorus source. None of the strains were able to grow when glyphosate was introduced as a sole carbon source. Two microbial strains: AQ5–12 and AQ5–13, were found to be the best degraders among them as they were able to withstand up to 12 ml/L of the Roundup® glyphosate formulation and 200 ppm of analytical grade glyphosate. Based on 16s rRNA and biochemical tests, AQ5–12 was identified as Burkholderia vietnamiensis, whereas AQ5–13 was identified as Burkholderia sp. AQ5–12, with the latter possessing better degradation capability compared to AQ5–13 with utilisation of 91 and 74% of 50 ppm glyphosate, respectively. The best optimum degradation conditions were seen at the temperature of 30 °C and a pH of 6 for both strains. Based on these results, both strains displayed their potential to be used in the bioremediation of glyphosate-contaminated environment

Environmental fate and degradation of glyphosate in soil

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

Isolation and characterisation of a Mo-reducing bacterium from Malaysian soil

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