Study On Phenol And Formaldehyde Degrading Characteristics Of The Fungus Aspergillus Nomius SGFA1

Nowadays, phenol and formaldehyde are often used as important chemical rawmaterials in industrial production activities. They were applied in organic synthesisprocess, including production process of synthetic resins, pharmaceutical products, andacetate dye. Therefore, much waste water generated by these industrial processescontains a large amount of phenol and formaldehyde. Microbial biological treatment ofsewage without secondary pollution has been widely promoted and researched.Filamentous fungi we tested in this study were isolated from sewage discharged by afurniture factory in Haerbin. And it was identified as Aspergillus nomiu SGFA1andpreserved by our laboratory in previous study. Phenol and formaldehyde biodegradationproperties of A. nomiu SGFA1were preliminary explored. Using response surfacemethodology analyzed the optimum environmental conditions for A. nomiu SGFA1metabolized under simulative combined pollution environment consisted of phenol andformaldehyde. Testing the interference between degradation which caused byco-existence of formaldehyde and phenol during the biodegradation process. Besides,activities of key enzyme participated in the degradation progress of phenol andformaldehyde was measured, and relationships between enzyme and biodegradationwere further explained. The main results are as follows:1. Phenol biodegradation abilities and tolerance of A. nomiu SGFA1were testedby changing a series of external conditions. When the rotation speed was180rpm, the optimum conditions for the degradation of phenol are as follows: Add50mL mineral salt medium (containing0.5%glucose, pH5) in to250mL flask,inoculated with seed bacteria with a dry weight of0.01g, cultured at28℃.Under optimization conditions, A. nomiu SGFA1completely degraded500mg/L and750mg/L phenol solution within a week. And the maximumtolerated concentration of phenol was at1200mg/L.2. We used Box-Behnken Design (BBD) of response surface methodology (RSM)to optimize temperature, pH and proportion of glucose conte nt three factorsand maximizing degradation rate of phenol and formaldehyde use of high, medium and low levels of experimental. According fit quadratic polynomialregression models, finding the most optimal design conditions for the tworesponses: containing1.2%glucose, pH is4.3, temperature is27.5℃. Underoptimum conditions for biodegradation, SGFA1degraded86.9%750mg/Lphenol and87.5%2400mg/L formaldehyde after a week continuous culture.3. When A. nomiu SGFA1biodegraded solution containing both phenol andformaldehyde, the degradation rate of two pollutants would subject toinhibition. Along with the addition of formaldehyde and the concentration ofphenol is constant as750mg/L, phenol degradation rate shows an inhibitioneffect which gradually decreased from98.7%to72.6%. When theconcentration of formaldehyde was constant as2400mg/L, degradation rate offormaldehyde was significantly reduced from95.1%down to14.4%, due to theincrease amount of phenol.4. Inoculated A. nomiu SGFA1into mineral salt medium containing mixture ofphenol and formaldehyde pollutants. Activities of phenol hydroxylase andformaldehyde dehydrogenase were evaluated. At the beginning of theexperiments, none of enzymes was detected. After A. nomiu SGFA1begun todegraded phenol and formaldehyde, activities of two enzymes were evaluated.With prolonged incubation time, A. nomiu SGFA1metabolized phenol andformaldehyde, respectively, and activities of phenol hydroxylase andformaldehyde dehydrogenase gradually increased during the biologicaldegradation process. Formaldehyde dehydrogenase reached the maximumvalue firstly. Results indicate a trend of A. nomiu SGFA1that biodegradeformaldehyde first, metabolized phenol later.