Screening of White-Rot Fungi Isolates for Decolorization of Pulp and Paper Mill Effluent and Assessment of Biodegradation and Biosorption Processes.

Ten white-rot fungal isolates were evaluated for the decolorization potential of pulp and paper mill effluent. Trametes elegans PP17-06, Pseudolagarobasidium sp. PP17-33, and Microporus sp.2 PP17-20 showed the highest decolorization efficiencies between 42 and 54% in 5 d. To reveal the mechanisms involved in decolorization and assess the long-term performance, PP17-06, which showed the highest decolorization efficiency, was further investigated. It could reduce the ADMI color scale by 63.6% in 10 d. However, extending the treatment period for more than 10 d did not significantly enhance the decolorization efficiencies. The maximum MnP activity of 3.27 U L-1 was observed on the 6 d during the biodegradation. In comparison, laccase activities were low with the maximum activity of 0.38 U L-1 (24 d). No significant LiP activities were monitored during the experiment. Dead fungal biomass showed an optimum decolorization efficiency of 44.18% in 8 d employing the biosorption mechanism. No significant changes in the decolorization efficiency were observed after that, suggesting the equilibrium status was reached. These results revealed that PP17-06 has the potential to decolorize pulp and paper mill effluent by employing both biodegradation and biosorption processes.

Productivity of Pseudomonas putida TISTR 1522 in polyhydroxyalkanoates (PHAs) production from saponified palm oil.

Polyhydroxyalkanoates (PHAs) have attracted attention as an environmentally degradable bioplastic which potentially replaces synthetic polymers used in a wide range of industries. One of most promising microorganisms for the production of PHAs is Pseudomonas putida. In this study, we purpose to develop sustainable processes to convert abundant palm oil available in local market to high value PHAs and optimize PHAs production by Pseudomonas putida TISTR 1522 from saponified palm oil. We found that the highest yield of PHAs production (0.95 g/L, 40.15%) was obtained in culture medium supplemented with 1% (w/v) fatty acid salt by P. putida TISTR 1522 after 24-h cultivation. The intracellular PHAs were located in granules inside the cells, which fluoresced bright yellow by staining with Nile red. The physical appearance of intracellular PHAs investigated by transmission electron microscope (TEM) revealed that PHAs accumulate in granules, about 3-10 granules per cell. These granules are white and roundish-shaped with 0.3-0.5-µm diameter. The 1H NMR spectrum represented the typical characters of medium-chain length-PHAs. This variation of all parameters was successfully demonstrated a good intracellular PHAs accumulation in P. putida TISTR 1522 by fatty acid salt utilization.

Utilization of oil palm decanter cake for valuable laccase and manganese peroxidase enzyme production from a novel white-rot fungus, Pseudolagarobasidium sp. PP17-33.

Oil palm decanter cake (OPDC) in the current study was converted to valuable products as laccase and manganese peroxidase (MnP) by an undescribed strain of the white-rot fungus, Pseudolagarobasidium sp. PP17-33. The optimization to enhance the production of enzymes through solid-state fermentation was performed using Plackett-Burman design and response surface methodology. The highest observed laccase was 5.841 U/gds and observed MnP was 5.156 U/gds, which enhanced yield by 2.59-fold and 1.94-fold from the non-optimization. The optimized medium (mg/g of OPDC) consisted of 0.852 mg CuSO4·5H2O, 13.512 mg glucose, 2 mg yeast extract, 0.2 mg KH2PO4, 1.5 mg MgSO4·7H2O, 0.01 mg FeSO4·7H2O, 0.15 mg MnSO4·H2O, 0.01 mg ZnSO4·7H2O and 0.3 mg Tween 80 (pH 5.0) when incubated at 30 °C for 7 days. The most significant variables of laccase and MnP productions were CuSO4·5H2O and glucose concentrations. This study is the first to report on the production of ligninolytic enzymes from OPDC waste using white-rot fungi. In addition, five different white-rot fungi, Coriolopsis aspera, C. retropicta, Dentipellis parmastoi, Nigroporus vinosus and Tyromyces xuchilensis, are newly observed producers of ligninolytic enzymes in Thailand. The results obtained from this study are significant not only for agro-industrial waste management but also for value-added enzyme production.