Reuse of Immobilized Weissella cibaria PN3 for Long-Term Production of Both Extracellular and Cell-Bound Glycolipid Biosurfactants

Abstract

Lactic acid bacteria (LABs) are generally recognized as safe (GRAS), and therefore, LAB biosurfactants are beneficial with negligible negative impacts. This study aims to maintain the biosurfactant producing activity of an LAB strain, Weissella cibaria PN3, by immobilizing the bacterial cells on a commercial porous carrier. For biosurfactant production, 2% soybean oil was used as the carbon source. After 72 h, immobilized cells were reused by replacing production medium. The extracellular and cell-bound biosurfactants were extracted from the resulting cell-free broth and cell pellets, respectively. SEM images of used immobilizing carriers showed increased surface roughness and clogged pores over time. Thus, the immobilizing carriers were washed in PBS buffer (pH 8.0) before reuse. To maintain biosurfactant production activity, immobilized cells were reactivated every three production cycles by incubating the washed immobilizing carriers in LB medium for 48 h. The maximum yields of purified extracellular (1.46 g/L) and cell-bound biosurfactants (1.99 g/L) were achieved in the 4th production cycle. The repeated biosurfactant production of nine cycles were completed within 1 month, while only 2 g of immobilized cells/L were applied. The extracellular and cell-bound biosurfactants had comparable surface tensions (31 – 33 mN/m); however, their CMC values were different (1.6 and 3.2 g/L, respectively). Both biosurfactants had moderate oil displacement efficiency with crude oil samples but formed emulsions well with gasoline, diesel, and lavender, lemongrass and coconut oils. The results suggested that the biosurfactants were relatively hydrophilic. In addition, the mixing of both biosurfactants showed a synergistic effect, as seen from the increased emulsifying activity with palm, soybean and crude oils. The biosurfactants at 10 – 16 mg/mL showed antimicrobial activity toward some bacteria and yeast but not filamentous fungi. The molecular structures of these biosurfactants were characterized by FTIR as different glycolipid congeners. The biosurfactant production process by immobilized Weissella cibaria PN3 cells was relatively cheap given that two types of biosurfactants were simultaneously produced and no new inoculum was required. The acquired glycolipid biosurfactants have high potential to be used separately or as mixed biosurfactants in various products, such as cleaning agents, food-grade emulsifiers and cosmetic products.

Copper and chromium removal from industrial sludge by a biosurfactant-based washing agent and subsequent recovery by iron oxide nanoparticles

“…Biosurfactants, including glycolipids, lipopeptides, and phospholipids, were produced by Weissella cibaria PN3 and Brevibacterium casei NK8. Glycolipids were produced by Weissella cibaria PN3 with 2% (v/v) soybean oil as a substrate as described in Subsanguan et al 7 . This bacterium produced glycolipids in the form of extracellular and cell-bound molecules.…”

“…The bacterium was cultured under alkaline conditions to allow the utilization of 5% (w/w) coconut oil cake as a substrate following Khondee et al 8 . Crude PN3 and NK8 biosurfactants were extracted from cell-free broth containing biosurfactant molecules using solvents according to Subsanguan et al 7 and Khondee et al 8 , respectively. The stock solution of biosurfactant was prepared by dissolving crude biosurfactant in phosphate buffer solution (PBS, pH 8.0) to the required concentration.…”

“…The washing procedure is simple, cost-effective, and fast; however, the washing agent should be environmentally friendly, biodegradable, and inexpensive to prevent secondary environmental pollution 6 . In this study, biosurfactant-based washing agents were formulated by mixing biosurfactants from 2 bacteria, Weissella cibaria PN3 and Brevibacterium casei NK8, which have different molecular structures and properties 7 , 8 . Each biosurfactant has been investigated for its potential application in environmental remediation and agricultural enhancement 8 , 9 , however, the mixing of these two biosurfactants has never been conducted.…”

“…The sludge contained high concentrations of Cu (> 4500 mg/kg) and Cr (> 5000 mg/kg) and had been produced in large amounts annually. Biosurfactants from Weissella cibaria PN3 and Brevibacterium casei NK8 were selected based on their different molecular structures and potential cost reduction when using food and agro-industrial wastes as substrates 7 , 8 . The nontoxic and recyclable Fe 3 O 4 nanoparticles were synthesized by a simple coprecipitation method, and the effect of residual biosurfactant and pH in the washing agent on the activity of nanoparticles was investigated.…”

Extraction, purification and applications of biosurfactants based on microbial-derived glycolipids and lipopeptides: a review

“…This is an innovative use of soil flushing that also supports sustainability. The reuse of biosurfactants after washing allows the economical use of these surfactants (Subsanguan et al 2020). The oil recovery from an oil spill can be highly enhanced with the help of biosurfactants produced from various microbial strains (Ravindran et al 2020).…”