Encapsulation of Pannonibacter phragmitetus LSSE-09 in alginate–carboxymethyl cellulose capsules for reduction of hexavalent chromium under alkaline conditions

Abstract

Cr(VI) was efficiently reduced to Cr(III) by Pannonibacter phragmitetus LSSE-09 encapsulated in liquid-core alginate-carboxymethyl cellulose capsules under alkaline conditions. Taking into account the physical properties of the capsules, the activity of encapsulated cells, and total Cr(III) concentration in the supernatant, optimal conditions (0.5% w/v sodium alginate; 2% w/v sodium carboxymethyl cellulose; 0.1 M CaCl₂; 30-min gelation time) for LSSE-09 encapsulation were determined. At optimal conditions, a relatively high reduction rate of 4.20 mg g ((dry weight))⁻¹ min⁻¹ was obtained. Total Cr(III) concentration in the supernatant was significantly decreased after reduction, because 63.7% of the formed soluble organo-Cr(III) compounds compared with those of free cells were captured by the relatively smaller porous structure of alginate capsules. The optimal pH value (9.0) for Cr(VI) reduction was not changed after encapsulation. In addition, encapsulated LSSE-09 showed no appreciable loss in activity after eight repeated cycles at 37°C, and 85.7% of its initial activity remained after 35-day storage at 4°C. The results suggest that encapsulated LSSE-09 in alginate-carboxymethyl cellulose capsules has potential biotechnological applications for the detoxification of Cr(VI)-contaminated wastewater.

Controlled root targeted delivery of fertilizer using an ionically crosslinked carboxymethyl cellulose hydrogel matrix

“…This control over fertilizer release is possible due to CMC hydrogels being able to encapsulate a wide variety of bioactive molecules, both hydrophobic and hydrophilic, such as glucose oxidase, aldicarb (a carbamate insecticide), and bovine serum albumin (Wu and Choi 2004Kok et al 1999Zhang et al 2001Kulterer et al 2012). Even microorganisms such as Pannonibacter phragmitetus may be encapsulated by CMC materials (Xu et al 2011). …”

Genomic insights of Pannonibacter phragmitetus strain 31801 isolated from a patient with a liver abscess

“…Thus, type IV secretion systems significantly facilitate the adaptation to dramatic environmental changes which confer the spread of antibiotic resistance among microorganisms (Zechner, Lang, & Schildbach, ). Other highlights from these regions are the presence of several genes that are involved in detoxification of heavy metals including arsenic transporters, manganese transporter, zinc transporter ZitB, lead/cadmium/zinc, and mercury transporting ATPase and copper oxidase, which agrees that P. phragmitetus has good heavy metal resistance (Xu et al., ; Shi et al., ).…”

“…Pannonibacter phragmitetus survives in extreme environments including hot springs (Bandyopadhyay, Schumann, & Das, ; Coman, Druga, Hegedus, Sicora, & Dragos, ), alkaline environments (pH 7.0–11.0), zero to high salinity (no NaCl as well as up to 5% [w/v] NaCl) (Borsodi et al., ). Currently, the studies on P. phragmitetus mainly focused on its bioremediation potentials including reduction of heavy metal chromium and detoxification of polycyclic aromatic compounds (PAHs) under extreme conditions (Borsodi et al., ; Xu et al., ; Shi et al., ; Wang et al., ; Wang, Jin, Zhou, & Zhang, ). For example, Shi et al.…”

Reduction of hexavalent chromium by Pannonibacter phragmitetus LSSE-09 coated with polyethylenimine-functionalized magnetic nanoparticles under alkaline conditions

“…This Gram-negative bacteria showed a strong potential to reduce Cr (VI) to Cr (III) aerobically and anaerobically under alkaline conditions [10]. We have evaluated the capability of strain LSSE-09 encapsulated in alginate capsules for reducing Cr (VI) along with organo-Cr (III) removal [37]. However, due to the lower diffusional limitations and steric hindrance, the Cr (VI)-reduction rate of encapsulated cells was lower than that of free cells.…”