Enhanced production of amylase, pyruvate and phenolic compounds from glucose by light-driven Aspergillus niger-CuS nanobiohybrids.

BACKGROUND: The demand for value-added compounds such as amylase, pyruvate and phenolic compounds produced by biological methods has prompted the rapid development of advanced technologies for their enhanced production. Nanobiohybrids (NBs) make use of both the microbial properties of whole-cell microorganisms and the light-harvesting efficiency of semiconductors. Photosynthetic NBs were constructed that link the biosynthetic pathways of Aspergillus niger with CuS nanoparticles. RESULTS: In this work, NB formation was confirmed by negative values of the interaction energy, i.e., 2.31 × 108 to -5.52 × 108 kJ mol-1 for CuS-Che NBs, whereas for CuS-Bio NBs the values were -2.31 × 108 to -4.62 × 108 kJ mol-1 for CuS-Bio NBs with spherical nanoparticle interaction. For CuS-Bio NBs with nanorod interaction, it ranged from -2.3 × 107 to -3.47 × 107 kJ mol-1 . Further, the morphological changes observed by scanning electron microscopy showed the presence of the elements Cu and S in the energy-dispersive X-ray spectra and the presence of CuS bonds in Fourier transform infrared spectroscopy indicate NB formation. In addition, the quenching effect in photoluminescence studies confirmed NB formation. Production yields of amylase, phenolic compounds and pyruvate amounted to 11.2 µmol L-1, 52.5 µmol L-1 and 28 nmol µL-1, respectively, in A. niger-CuS Bio NBs on the third day of incubation in the bioreactor. Moreover, A niger cells-CuS Bio NBs had amino acids and lipid yields of 6.2 mg mL-1 and 26.5 mg L-1, respectively. Furthermore, probable mechanisms for the enhanced production of amylase, pyruvate and phenolic compounds are proposed. CONCLUSION: Aspergillus niger-CuS NBs were used for the production of the amylase enzyme and value-added compounds such as pyruvate and phenolic compounds. Aspergillus niger-CuS Bio NBs showed a greater efficiency compared to A. niger-CuS Che NBs as the biologically produced CuS nanoparticles had a higher compatibility with A. niger cells. © 2022 The Authors. Journal of Chemical Technology and Biotechnology published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry (SCI).

Light driven Aspergillus niger-ZnS nanobiohybrids for degradation of methyl orange.

Inorganic-microbial hybrid systems have potential to be sustainable, efficient and versatile chemical synthesis platforms by integrating the light-harvesting properties of semiconductors with microbial cells. Here, we demonstrate light-driven photocatalytic semiconducting Aspergillus niger cells-ZnS nanoparticles for enhanced removal of the dye methyl orange. Chemically synthesized ZnS nanoparticles exhibited a zinc blende pattern in X-ray diffraction, had a dimension of 20-90 nm with a band gap (Ebg) of 3.4 eV at 1.83 × 1018 photons/second. Biologically synthesized ZnS nanoparticles of 40-90 nm showed a hexagonal pattern in the X-ray powder diffraction spectra with an Ebg 3.7 eV at 1.68 × 1018 photons/second. At a methyl orange (MO) concentration of 100 mg/L, dosage of 0.5 × 105 mol catalyst and pH 4, a 97.5% and 98% removal efficiency of MO was achieved in 90 min and 60 min for, respectively, chemically and biologically synthesized ZnS nanobiohybrids in the presence of UV-A light. The major degradation products of photocatalysis for chemically synthesized ZnS nanobiohybrids were naphtholate (C10H7O m/z 143) and hydroquinone (C9H5m/z 113). For the biologically synthesized ZnS nanobiohybrids, the degradation products were hydroquinone (C9H5m/z 113) and 2-phenylphenol (C12H10O m/z 170).

Enhanced removal of hydrocarbons BTX by light-driven Aspergillus niger ZnS nanobiohybrids.

Benzene, toluene, and xylene (BTX) are volatile aromatic compounds used in industries, however, they are hazardous when released into the environment. BTX degradation by Aspergillus niger cells combined with semiconducting zinc sulfide (ZnS) nanoparticles was explored in batch systems. Experiments were conducted individually for benzene, toluene, and xylene as well as in binary and trinary mixtures using A. niger cells-ZnS nanobiohybrids. The mechanism governing the removal of BTX by both A. niger cells and A. niger cells-ZnS nanobiohybrids were elucidated. Complete BTX degradation was achieved in 75 min and 60 min, respectively, by nanobiohybrids composed of chemical and biological ZnS nanoparticles in the presence of UV-A light at 1.83 * 1018 photons/second and 1.68 * 1018 photons/second, respectively. The removal efficiency was in the order of the molecular weight for A. niger cells, whereas for the light-driven A. niger-ZnS nanobiohybrids, the removal efficiency was according to the methyl group number. Further, the respiratory coefficient and volumetric mass transfer coefficient (Ka) values are higher for A. niger cells compared to the light-driven A. niger-ZnS nanobiohybrids.