The growth of white-rot fungus Pleurotus eryngii F032 in a suitable medium can degrade an azo dye Reactive Black 5 (RB5), because of its ability to produce ligninolytic enzymes such as lignin peroxidase (LiP), manganese peroxidase (MnP), and laccase that able to degrade and transform the complex structure of the dye into a less toxic compound. The effect of environmental factors such as initial concentration of Reactive Black 5, pH, temperature of growth medium, surfactant (Tween 80), and agitation were also investigated. The productions of ligninolytic enzymes were enhanced by increasing the white-rot fungi growth in optimum conditions. The decolorization of Reactive Black 5 were analyzed by using UV-vis spectrophotometer at the maximum absorbance of 596 nm. The whiterot fungus, P. eryngii F032 culture exhibited 93.56 % decolorization of 10 mg/L RB5 within 72 h of incubation in dark condition with agitation. The optimum pH and temperature for the decolorizing activity was recorded at pH 3 and 40°C, respectively. The addition of surfactant (Tween 80) increased the decolorization to 93.57 % and agitation of growth medium at 120 rpm enhanced the distribution of nutrients to the fungus thus optimized the enzymatic reaction that resulted maximum decolorization of RB5 which was 93.57 %. The molecular docking studies were performed using Chimera visualization software as to analyze the decolorization mechanism of RB5 at molecular level.

Highlights 39• Liquid pineapple waste, a novel nutritious low cost growth medium. 40• Post-treatment of bacterial effluent for eco-friendly disposal. 41• Violet pigment stable at optimum conditions. 42• Violacein and deoxyviolacein isolated and characterized. 43• Crude violet pigment shows bioactivity. 44 • The first report on the production of violet pigment using liquid pineapple waste 45 medium. 46 47 48 Abstract 49 50 Synthetic pigments have been utilized in numerous industries including textile, cosmetic, 51 food and pharmaceuticals. However, the drawbacks of these pigments, namely toxicity 52 problems have kindle the interest in natural pigments. In view of this, the use of natural 53 pigments such as those from bacterial origin offers interesting alternative for industrial 54 application. However, large scale applications of natural pigments are often hindered by the 55 high production cost. This study evaluates on the feasibility of using liquid pineapple waste 56 for the production of violacein by a locally isolated Chromobacterium violaceum UTM5 both 57 in shake flask and 50 L bioreactor. The use of optimized growth parameters including culture 58 conditions, concentration of liquid pineapple waste and supplementation of L-tryptophan 59 resulted in violacein yield of 16256 ± 440 mg L -1 . Post treatment of the effluent effectively 60 reduced the COD, turbidity and TSS contents to less than 1 mg L -1 , 1.57 ± 0.2 NTU and 2.7 ± 61 0.6 mg L -1 respectively. Violet pigment exhibited good stability during the entire storage 62 period of 30 days at pH 7, temperature 25 -30 °C and under dark condition. The violet 63 pigment has a good antimicrobial activity against selected microorganisms. Of interest, the 64 pigment was active against Staphylococcus aureus ATCC 29213 and methicillin-resistant 65 Staphylococcus aureus (MRSA) ATCC 43300 with MIC value of 7.8 and 15.6 µg mL -1 , 66 respectively. However, the pigment is toxic to the V79-4 Chinese hamster lung cells with low 67 selectivity index. The purified compounds were determined as violacein and deoxyviolacein 68 using FT-IR, LC-MS and NMR respectively. Results confirmed the feasibility of using liquid 69 pineapple waste as a potential low cost growth medium for large-scale cultivation of violet 70 pigment using C. violaceum UTM5. Synthetic colours are mostly used in the food processing and cosmetic industries as natural 81 colorants are expensive, less stable and possess lower intensity. 1,2 Conversely, these 82 synthetic colorants have been or being banned due to their carcinogenicity, hyperallergenicity 83 and toxicological issues. Thus, natural pigments are progressively in an increasing demand as 84 they are biodegradable, non-toxic to humans and have precise differences in colour tones. 3,4 85 A wide range of pigment applications in fields of food, cosmetics, pharmaceuticals and 86 textiles has contributed to its escalating needs by colouring agents in many industries. 1 In 87 comparison to colorants extracted from plant and animals, microorganisms ...

The use of biomaterials or microorganisms in PAHs degradation had presented an eye-catching performance. Pleurotus eryngii is a white rot fungus, which is easily isolated from the decayed woods in the tropical rain forest, used to determine the capability to utilize naphthalene, a two-ring polycyclic aromatic hydrocarbon as source of carbon and energy. In the meantime, biotransformation of naphthalene to intermediates and other by-products during degradation was investigated in this study. Pleurotus eryngii had been incubated in liquid medium formulated with naphthalene for 14 days. The presence of metabolites of naphthalene suggests that Pleurotus eryngii begin the ring cleavage by dioxygenation on C1 and C4 position to give 1,4-naphthaquinone. 1,4-Naphthaquinone was further degraded to benzoic acid, where the proposed terepthalic acid is absent in the cultured extract. Further degradation of benzoic acid by Pleurotus eryngii shows the existence of catechol as a result of the combination of decarboxylation and hydroxylation process. Unfortunately, phthalic acid was not detected in this study. Several enzymes, including manganese peroxidase, lignin peroxidase, laccase, 1,2-dioxygenase and 2,3-dioxygenase are enzymes responsible for naphthalene degradation. Reduction of naphthalene and the presence of metabolites in liquid medium showed the ability of Pleurotus eryngii to utilize naphthalene as carbon source instead of a limited glucose amount.

Herein, we systematically reported the capability of T. harzianum RY44 for decolorization of Mordant orange-1. The fungi strains were isolated from the Universiti Teknologi Malaysia tropical rain forest. For initial screening, the decolorization was conducted using 50 strains of the fungi for 20 days incubation time and the best performance was selected. Then, the decolorization capability and fungal biomass were evaluated using different dye concentrations, namely, 0, 50, 75 and 100 ppm. Effects of the carbon sources (fructose, glucose, and galactose), nitrogen sources (ammonium nitrate, ammonium sulfate and yeast extract), surfactant (tween 80), aromatic compounds (benzoic acid, catechol and salicylic acid), and pH on the decolorization efficiency were examined. This study has found that the employed carbon sources, nitrogen sources, and aromatic compounds strongly enhance the decolorization efficiency. In addition, increasing the surfactant volume and pH generally decreased the decolorization efficiencies from 19.5 to 9.0% and 81.7 to 60.5%, respectively. In the mechanism philosophy, the present work has found that Mordant orange-1 were initially degraded by T. harzianum RY44 to benzoic acid and finally transformed into salicylic acid.

Characterization of anthracene metabolites produced by Armillaria sp. F022 was performed in the enzymatic system. The fungal culture was conducted in 100-mL Erlenmeyer flask containing mineral salt broth medium (20 mL) and incubated at 120 rpm for 5-30 days. The culture broth was then centrifuged at 10,000 rpm for 45 min to obtain the extract. Additionally, the effect of glucose consumption, laccase activity, and biomass production in degradation of anthracene were also investigated. Approximately, 92 % of the initial concentration of anthracene was degraded within 30 days of incubation. Dynamic pattern of the biomass production was affected the laccase activity during the experiment. The biomass of the fungus increased with the increasing of laccase activity. The isolation and characterization of four metabolites indicated that the structure of anthracene was transformed by Armillaria sp. F022 in two routes. First, anthracene was oxidized to form anthraquinone, benzoic acid, and second, converted into other products, 2-hydroxy-3-naphthoic acid and coumarin. Gas chromatography-mass spectrometry analysis also revealed that the molecular structure of anthracene was transformed by the action of the enzyme, generating a series of intermediate compounds such as anthraquinone by ring-cleavage reactions. The ligninolytic enzymes expecially free extracellular laccase played an important role in the transformation of anthracene during degradation period.