Cutinase production from Fusarium verticillioides using response surface methodology and its application as potential insecticide degrader

Cutinase, a multifunctional enzyme, has shown great potential in environmental applications such as degradation of plastics and some commonly used insecticides. To overcome these environmental threatening problems, attempts should be made to enhance enzyme production. In the present study, a cutinolytic fungus was isolated from the soil. Based on 18 s rDNA sequencing, it was found that isolate AR08 belongs to the genus Fusarium and clades with Fusarium verticillioides. Optimization of medium composition for enhancement in cutinase production was done using. classical and statistical methods. Firstly, key factors were selected by one variable at a time (OVAT) method, then by Plackett- Burman design. Concentration of these important factors was optimized by Central Composite design. A total of 30 experiments were conducted and the optimized concentration of sodium nitrate, dipotassium hydrogen phosphate, flaxseed oil and zinc sulphate were found to be 0.455%, 0.305%, 2% and 0.0355% respectively. The result of ANOVA (analysis of variance) test revealed that p value was significant for the model. Interaction between flaxseed oil and sodium nitrate was found to have a positive effect on cutinase production. A 14.57 fold increase in enzyme activity was found under optimized conditions with the maximum cutinase activity of 626.6 IUml-1.

A minireview on the bioremediative potential of microbial enzymes as solution to emerging microplastic pollution

Accumulating plastics in the biosphere implicates adverse effects, raising serious concern among scientists worldwide. Plastic waste in nature disintegrates into microplastics. Because of their minute appearance, at a scale of <5 mm, microplastics easily penetrate different pristine water bodies and terrestrial niches, posing detrimental effects on flora and fauna. The potential bioremediative application of microbial enzymes is a sustainable solution for the degradation of microplastics. Studies have reported a plethora of bacterial and fungal species that can degrade synthetic plastics by excreting plastic-degrading enzymes. Identified microbial enzymes, such as IsPETase and IsMHETase from Ideonella sakaiensis 201-F6 and Thermobifida fusca cutinase (Tfc), are able to depolymerize plastic polymer chains producing ecologically harmless molecules like carbon dioxide and water. However, thermal stability and pH sensitivity are among the biochemical limitations of the plastic-degrading enzymes that affect their overall catalytic activities. The application of biotechnological approaches improves enzyme action and production. Protein-based engineering yields enzyme variants with higher enzymatic activity and temperature-stable properties, while site-directed mutagenesis using the Escherichia coli model system expresses mutant thermostable enzymes. Furthermore, microalgal chassis is a promising model system for "green" microplastic biodegradation. Hence, the bioremediative properties of microbial enzymes are genuinely encouraging for the biodegradation of synthetic microplastic polymers.

High lipid accumulating bacteria isolated from dairy effluent scum grown on dairy wastewater as potential biodiesel feedstock

The study evaluated the lipid accumulation potential of bacteria isolated from dairy effluent scum by the valorization of dairy wastewater as a renewable feedstock for biodiesel production. Three oleaginous bacteria (i.e. DS-1, DS-6, and DS-7) were screened on the basis of their lipid accumulation (>20% lipid content) and productivity on a glucose-based medium. The effect of different carbon sources (i.e. lactose, sucrose, starch, glucose, and xylose) on lipid accumulation capacity of the bacterial isolates was evaluated. The rod-shaped oleaginous bacterium DS-7 could accumulate 90% lipid with 1.2 g/l·d lipid productivity using lactose as a sole source of carbon. The bacteria could efficiently utilize dairy wastewater (~50% reduction in BOD) with reasonably high lipid accumulation (72.78%), biomass production (4.29 g/l) and lipid productivity (0.727 g/l·d). The lipids accumulated by bacterium DS-7 were mostly neutral lipids and contained fatty acids of chain length C14:0-C18:0, as confirmed by nile red staining and nuclear magnetic resonance (NMR) spectroscopy. Fourier-transform infrared (FTIR) spectroscopy and gas chromatography (GC) analysis of fatty acid methyl esters (FAME) revealed that transesterified bacterial lipids from the isolated bacteria DS-7 are suitable for biodiesel applications.

Optimization of physical parameters for enhanced production of lipase from Staphylococcus hominis using response surface methodology

Lipase, a versatile hydrolytic enzyme, is gaining more importance in environmental applications such as treatment of oil and grease containing wastewater, pretreatment of solid waste/industrial wastewater for anaerobic treatment. In the present study, the attempts have been made to improve the production of lipase from Staphylococcus hominis MTCC 8980 by optimization of pH, temperature, and agitation speed in lab scale shake flasks culture. The experiments were designed using the full factorial central composite design of experiment. A total of 20 experiments were conducted, and the optimized pH, temperature, and agitation speed were found to be 7.9, 33.1 °C, and 178.4 rpm, respectively. The results of the analysis of variance (ANOVA) test revealed that the linear terms for temperature and agitation were significant (p value < 0.05). Interaction for pH and agitation speed was found to have a significant effect on lipase production from S. hominis MTCC 8980. A 150% increase in enzyme activity was observed under the optimized conditions with the maximum lipase activity of 1.82 U/ml. Further enhancement of enzyme activity can be expected from the optimization of medium components.

Production of cutinase from Fusarium falciforme and its application for hydrophilicity improvement of polyethylene terephthalate fabric

Among 23 isolates of cutinase-producing fungi from Thailand, one strain of Fusarium falciforme PBURU-T5 exhibited the greatest cutinase activity (3.36 ± 0.12 U ml^-1) against p-nitrophenyl butyrate. This strain was found to produce an inducible cutinase when cultivated in the liquid mineral medium containing cutin from papaya peel as the sole carbon source. By optimizing the production condition based on the central composite experimental design, the maximal cutinase activity up to 4.82 ± 0.18 U ml^-1 was attained under the condition: 0.4% (w/v) papaya cutin as the carbon source, 0.3% (w/v) peptone as the nitrogen source, incubation temperature at 30 °C for 4 days, and initial pH 7.0. The crude enzyme was optimally active at 35 °C and pH 9.0 which was suitable for textile industrial application. The treatment with the crude PBURU-T5 cutinase (100 U g^-1 dry weight of fabric) could enhance the wetting time, water adsorption and moisture regain of polyethylene terephthalate fabric up to 1.9-, 1.2- and 1.3-fold, respectively, comparing with the conventional 1M NaOH treatment. The increment of these fabric properties by enzymatic treatment could facilitate the dyeing process and enhance the fabric softness. Thus, F. falciforme PBURU-T5 is the promising source of cutinase for the modification of the PET fabric surface.

Optimization of medium parameters by response surface methodology (RSM) for enhanced production of cutinase from Aspergillus sp. RL2Ct

Cutinases are hydrolytic enzymes which catalyzes esterification and trans-esterification reactions that make them highly potential industrial biocatalyst. In the present investigation microorganisms showing cutinase activity were isolated from plant samples. The strain showing maximum cutinase activity was identified by 18S rDNA sequencing as Aspergillus sp. RL2Ct and was selected for further studies. To achieve maximum enzyme production, the medium components affecting cutinase production were screened by Plackett-Burman followed by central composite design. The results obtained suggested that cutin, temperature and CaCl₂ have influenced the cutinase production significantly with very high confidence levels. Cutinase production was maximum (663 U/mg protein) when using cutin prepared from orange peel as sole source of carbon. An overall 4.33-fold increase in the production of cutinase was observed after optimization of culture conditions (including 2.5-fold increase using RSM) during 24 h of incubation. The production time of Aspergillus sp. RL2Ct cutinase is significantly lower than the most of the earlier reported cutinase-producing fungus.