Biodegradation of phenol by immobilized Aspergillus awamori NRRL 3112 on modified polyacrylonitrile membrane

Abstract

Covalent immobilization of Aspergillus awamori NRRL 3112 was conducted onto modified polyacrylonitrile membrane with glutaraldehyde as a coupling agent. The polymer carrier was preliminarily modified in an aqueous solution of NaOH and 1,2-diaminoethane. The content of amino groups was determined to be 0.58 mgeq g(-1). Two ways of immobilization were used-in the presence of 0.2 g l(-1) phenol and without phenol. The capability of two immobilized system to degrade phenol (concentration-0.5 g l(-1)) as a sole carbon and energy source was investigated in batch experiments. Seven cycles of phenol biodegradation were conducted. Better results were obtained with the immobilized system prepared in the presence of phenol, regarding degradation time and phenol biodegradation rate. Scanning electron micrographs of the polyacrylonitrile membrane/immobilized Aspergillus awamori NRRL at the beginning of repeated batch cultivation and after the 7th cycle were compared. After the 7th cycle of cultivation the observations showed large groups of cells. The results from the batch experiments with immobilized system were compared to the results produced by the free strain. Phenol biodegradation experiments were carried out also in a bioreactor with spirally wound membrane with bound Aspergillus awamori NRRL 3112 in a regime of recirculation. 10 cycles of 0.5 g l(-1) phenol biodegradation were run consecutively to determine the degradation time and rate for each cycle. The design of the bioreactor appeared to be quite effective, providing large membrane surface to bind the strain.

Enhanced degradation of phenol by Pseudomonas sp. CP4 entrapped in agar and calcium alginate beads in batch and continuous processes

“…FG03 immobilized in PVA degraded 95% of 800 mg l -1 phenol within 35 h (Liu et al 2009). A. awamori NRRL 3112 immobilized in polyacrylonitrile with glutaraldehyde as coupling agent showed better degradation rates than by free mycelia (Yordanova et al 2009). Under optimal conditions P. putida ATCC 11172 immobilized in Ca-alginate degraded phenol at a maximum rate of 250 mg l -1 h -1 (Hannaford and Kuek 1999).…”

“…A number of microorganisms have been shown to utilize phenol and its derivatives as sole sources of carbon and energy at varying concentrations, under aerobic conditions. They include several bacterial cultures (Agarry et al 2008;Babu et al 1995b;Chung et al 2003;El-Sayed et al 2003;Feitkenhauer et al 2003;Karigar et al 2006;Kumar et al 2005;Liu et al 2009;Ma et al 2010;Mordocco et al 1999;Prieto et al 2002;Shetty et al 2007), a few yeast strains (Agarry et al 2008;Fialova et al 2004;Yan et al 2005) and mycelial fungi (Agarry et al 2008;Anselmo et al 1989;Santos et al 2003;Yordanova et al 2009). Removal of phenol also has been carried out using activated sludge systems for the last several years (Amor et al 2005;Marrot et al 2008).…”

“…Ca-alginate has been used as the gel matrix in several studies for encapsulating strains of bacteria, yeasts, and mycelial fungi (Abd-El-Haleem et al 2003;Bandhyopadhyay et al 1999;Bettmann and Rehm 1984;Chung et al 2003;Dursun and Tepe 2005;Hannaford and Kuek 1999;Kapoor et al 1998;Karigar et al 2006;Keweloh et al 1989;Lakhwala et al 1992;Mordocco et al 1999;Santos et al 2003). Other polymers which were occasionally used for immobilizing phenol-degrading microorganisms were agar, polyacrylamide (PAA), polyacrylamide hydrazide (PAAH), polyvinyl alcohol (PVA), polysulfone hollow fiber membrane, and modified polyacrylonitrile membrane (Bettmann and Rehm 1985;Chen et al 2002;Juárez-Ramírez et al 2001;Karigar et al 2006;Liu et al 2009;Loh et al 2000;Yordanova et al 2009). All the phenol-degrading strains exhibited improved ability, to varying degrees, in the immobilized systems than as freely suspended cells.…”

Simultaneous Biodegradation of Phenol and n-Hexadecane by Cryogel Immobilized Biosurfactant Producing Strain Rhodococcus wratislawiensis BN38

“…For example, immobiliza tion technique could lead to the accomplishment of quite effective technological processes for bioreme diation of contaminated sites (Yordanova et al, 2009). The advantages of the process based on immobilized biomass include enhancing microbial cell stability, allowing continuous process of operation and avoid ing the biomassliquid separation requirement.…”

“…Many bacterial strains have been isolated with the abilities to degrade nhexadecane and phenol sepa rately, which are often used to represent the aliphatic and aromatic pollutant (Yordanova et al, 2009; Abdel Megeed et al, 2010;Tambekar et al, 2012). However, few strains have been reported to have the dual abilities (Sun et al, 2012).…”