Exploring the decolorization efficiency and biodegradation mechanisms of different functional textile azo dyes by Streptomyces albidoflavus 3MGH.

Efficiently mitigating and managing environmental pollution caused by the improper disposal of dyes and effluents from the textile industry is of great importance. This study evaluated the effectiveness of Streptomyces albidoflavus 3MGH in decolorizing and degrading three different azo dyes, namely Reactive Orange 122 (RO 122), Direct Blue 15 (DB 15), and Direct Black 38 (DB 38). Various analytical techniques, such as Fourier Transform Infrared (FTIR) spectroscopy, High-Performance Liquid Chromatography (HPLC), and Gas Chromatography-Mass Spectrometry (GC-MS) were used to analyze the degraded byproducts of the dyes. S. albidoflavus 3MGH demonstrated a strong capability to decolorize RO 122, DB 15, and DB 38, achieving up to 60.74%, 61.38%, and 53.43% decolorization within 5 days at a concentration of 0.3 g/L, respectively. The optimal conditions for the maximum decolorization of these azo dyes were found to be a temperature of 35 °C, a pH of 6, sucrose as a carbon source, and beef extract as a nitrogen source. Additionally, after optimization of the decolorization process, treatment with S. albidoflavus 3MGH resulted in significant reductions of 94.4%, 86.3%, and 68.2% in the total organic carbon of RO 122, DB 15, and DB 38, respectively. After the treatment process, we found the specific activity of the laccase enzyme, one of the mediating enzymes of the degradation mechanism, to be 5.96 U/mg. FT-IR spectroscopy analysis of the degraded metabolites showed specific changes and shifts in peaks compared to the control samples. GC-MS analysis revealed the presence of metabolites such as benzene, biphenyl, and naphthalene derivatives. Overall, this study demonstrated the potential of S. albidoflavus 3MGH for the effective decolorization and degradation of different azo dyes. The findings were validated through various analytical techniques, shedding light on the biodegradation mechanism employed by this strain.

Biochemical and toxicological characteristics of polyphenol oxidase from red palm weevil Rhynchophorus ferrugineus (Olivier) (Coleoptera: Curculionidae).

Red palm weevil (RPW) Rhynchophorus ferrugineus is the most destructive insect pests of numerous palm species in the world. The introduction of botanical extract(s) as integral part of an integrated pest management (IPM) programs against RPW will reduce the use of chemical insecticides. Polyphenol oxidase (PPO) is one of the RPW innate immune mechanisms and inhibition of such enzyme could result in a disorder of the insect's immune system. A one single PO isoenzyme has been purified from the hemolymph of the 12th instar larvae of RPW. Using L-DOPA as substrate, R. ferrugineus PPO exhibited specific activity 428 Units/mg proteins with 8.3-fold purification, optimum pH and temperature for activity at 7.5 and 40 °C, respectively and is enhanced by Cu2+ with 1.76-fold. The rank order for oxidizing R. ferrugineus PPO different substrates is catechol > pyrogallol > L-DOPA > pyrocatechuic acid and not tyrosine. The kinetic parameters Km, Vmax and Vmax/Km for L-DOPA are 3.3 mM, 1.3 µmol/ml/min, and 0.39, respectively. The catalytic efficiency of the enzyme towards catechol is 5.3-fold higher than that for L-DOPA. The enzyme completely inhibited by thiourea, ascorbic acid, dithiothreitol, and SDS. R. ferrugineus PPO is a catechol oxidase di-phenol: O2 oxidoreductase. Based on the toxicological studies of various botanical extracts, the IC50 ranged from 20 to 90 mg/ml. The enzyme completely inhibited by 50 mg/ml Cinnamomum camphora. Gallic acid, the major phenolic compound, has IC50 0.8 mM and competitively inhibited the enzyme with Ki 0.54 mM. C. camphora could be a useful natural RPW-controlling agent and used as integral part in IPM programs. This interpretation can be validated in future through an in vivo investigation.

Production of laccase enzyme from Curvularia lunata MY3: purification and characterization.

Laccase-producing fungus (MY3) was successfully isolated from soil samples collected from Mansoura Governorate, Egypt. This fungal isolate has shown a high laccase production level over other isolated fungi. The identity of this isolate was determined by the molecular technique 18SrRNA as Curvularia lunata MY3. The enzyme purification was performed using ammonium sulfate precipitation followed by Sephacryl S-200 and DEAE-Sepharose column chromatography. The denatured enzyme using SDS-PAGE had a molar mass of 65 kDa. The purified laccase had an optimum temperature at 40 °C for enzyme activity with 57.3 kJ/mol activation energy for 2,2'-azino-bis-3-ethylbenzothiazoline-6-sulfonic acid (ABTS) oxidation. The enzyme had an optimum pH of 5.0, and it has shown a high stability at the acidic range (4.5 to 5.5). Mn2+ and Mg2+ ions enhanced the enzyme activity, while most of the enzyme activity was inhibited by Hg2+. Some compounds such as 2-mercaptoethanol, L-cysteine, and sodium azide at a concentration of 10 mmol/L had shown a high suppression effect on the enzyme activity. The enzyme strongly oxidized ABTS and syringaldazine and moderately oxidized DMP and guaiacol. The antimicrobial activity of the purified enzyme towards three pathogenic strains (Escherichia coli ATCC-25922, Staphylococcus aureus NRRLB-767, and Candida albicans ATCC-10231) was evaluated for the potential use as an antimicrobial therapeutic enzyme.

Production of a novel α-amylase by Bacillus atrophaeus NRC1 isolated from honey: Purification and characterization.

Different bacterial isolates with amylolytic activity were insulated from various honey samples. The most active isolate was identified by the molecular 16SrRNA sequence technique as Bacillus atrophaeus NRC1. The bacterium showed maximum amylase production under optimum culture conditions at pH 6.0, 40 °C and after 24 h incubation. Two amylase isoenzymes (AmyI and AmyII) from Bacillus atrophaeus NRC1 have been purified to homogeneity by using ammonium sulfate precipitation, Sephacryl S-200 and DEAE-Sepharose chromatography. The major isoenzyme, AmyI, had a specific activity 4635 U/mg proteins with molecular weight of 61 kDa using SDS-PAGE electrophoresis. The maximum activity of AmyI against starch was determined at pH 6.0 and 50 °C. AmyI was stable up to 50 °C after incubation for 30 min, retained 65 and 23% of its activity at 60 and 70 °C, respectively. Pre-incubation with Ca2+, Mg2+ and Ba2+ cations for 30 min enhanced the enzyme activity; while it was completely inhibited by Hg2+. Varied inhibition degree of the enzyme activity was determined with K+, Ni2+, Zn2+, Na2+ and Cu2+ ions. AmyI was inhibited by EDTA, PMSF and SDS, while it was activated by l-Cysteine-HCl and DTT. AmyI had the ability to degrade starch, amylopectin, glycogen, amylose and lacked the affinity towards ß-1,4-linked xyloses.

Purification and characterization of acetylcholinesterase in Rhynchophorus ferrugineus (Olivier) (Coleoptera: Curculionidae).

Red palm weevil (RPW), Rhynchophorus ferrugineus, is one of the most destructive pests of cultivated palm trees. The application of synthetic insecticides is currently a main strategy for RPW control. In this study we estimated the distribution of acetylcholinesterase (AChE), as a detoxifying enzyme and the target site of inhibition by insecticides, using ASChI as substrate in different organs of the pest including whole gut, cuticle, fat body, head and haemolymph. The activity ranged from 314.9 to 3868 U in individual organs while the specific activity ranged from 99 to 340.8 U/mg proteins; the cuticle had the highest enzyme level. During larval development, the 11th instar larvae had the highest enzyme content with 5630 U in the cuticle, with a specific activity of 140 U/mg protein. The two major AChE isoenzymes were purified by chromatography on gel filtration and ion exchange columns. They had specific activities of 3504.3 and 2979 U/mg protein, molecular weights of 33 and 54 kDa and activation energies of 8.3 and 4.4 kcal/mol, respectively. Both isoenzymes had monomeric forms, optimum activity at pH 8.0 and 40 °C, were completely inhibited by Hg2+ and Cu2 and showed similar trends towards the inhibitors eserine, BW284C51 and iso-OMPA. The catalytic properties were compared with those previously recorded for different insect species. This work will pave the way for more studies for improving the understanding of insecticide resistance and developing the field application of synthetic insecticides for controlling R. ferrugineus to ensure successful application.