Effect of Cell-to-matrix Ratio in Polyvinyl Alcohol Immobilized Pure and Mixed Cultures on Atrazine Degradation

Abstract

Atrazine biodegradation by immobilized pure and mixed cultures was examined. A pure atrazinedegrading culture, Agrobacterium radiobacter J14a (J14a), and a mixed culture (MC), isolated from an atrazine-contaminated crop field, were immobilized using phosphorylated-polyvinyl alcohol (PPVA). An existing cell immobilization procedure was modified to enhance PPVA matrix stability. The results showed that the matrices remained mechanically and chemically stable after shaking with glass beads over 15 days under various salt solutions and pH values.The immobilization process had a slight effect on cell viability. With the aid of scanning electron microscopy, a suitable microstructure of PPVA matrices for cell entrapment was observed. There were two porous layers of spherical gel matrices, the outside having an encapsulation property and the inside containing numerous pores for bacteria to occupy. J14a and MC were immobilized at three cell-to-matrix ratios of 3.5, 6.7, and 20 mg dry cells/mL matrix. The atrazine biodegradation tests were conducted in an aerobic batch system, which was inoculated with cells at 2,000 mg/L. The tests were also conducted using free (non-immobilized) J14a and MC for comparative purpose. The cell-to-matrix ratio of 3.5 mg/mL provided the highest atrazine removal efficiency of 40-50% in 120 h for both J14a and MC. The free cell systems, for both cultures, presented much lower atrazine removal efficiencies compared to the immobilized cell systems at the same level of inoculation.

Ethanol production potential from fermented rice noodle wastewater treatment using entrapped yeast cell sequencing batch reactor

“…This could be from limitation of substrate diffusion in the entrapped cell systems leading to lower treatment efficiencies. Similar situation also reported in previous studies (Kim et al 2001;Song et al 2005;Siripattanakul et al 2008). However in later cycles (3-5), ECSBR (removal of 75 ± 10%) significantly performed superior over SBR (removal of 51.5 ± 11.5%).…”

“…A previous publication reviewed adsorption ability of entrapment matrices which was commonly found at the early stage of matrix utilization (Siripattanakul and Khan, 2010). In case of the entrapped cell reutilization, no or less adsorption would be observed (Siripattanakul et al 2008). It was clear that the entrapped yeast cell systems successfully reduced glucose by matrix adsorption (glucose immobilization) and biodegradation (glucose bioconversion) but the main process was biodegradation.…”

Effects of cell entrapment on growth rate and metabolic activity of pure cultures commonly found in biological wastewater treatment

“…Similar results were observed with mixed cultures [14]. Several studies reported that high amounts of cells inside the matrix lower the space for the diffusion of substrate and other necessary elements and in turn reduce and q [23,33,34]. In addition, the entrapped cells had less space to grow at higher initial cell concentrations (cell-to-matrix ratios).…”

“…PVA beads were found to be very durable against abrasion and pH variation and no recognizable destruction of bead appearance was observed during several months of operation in previous studies [23,24]. Alginate beads exhibit less durability than PVA beads and stabilization may be necessary to maintain its long-term operational efficiency [1,25,26].…”

Cryogels for Biotechnological Applications

“…Entrapment of spores were also used when Humicola lutea was immobilized in PVA crosslinked via N,N 0 -methylenebisacrylamide with or without added PEG. It Mixed culture Diesel-contaminated soil PVA-cryogel [33] Basic study Atrazine in water PVA-cryogel [34] Analytical applications Glucose analysis Glucose oxidase Enzyme immobilized in albumin/chitosan gel [22] Pseudomonas putida Detection of phenol Clark electrode used for detection [35] Pseudomonas sp.…”