Gellan Gum Production Research Articles

Recent advances in gellan gum production and modification for enhanced applicability in food printing and bioactive delivery applications

The importance of Gellan gum has been increasing gradually and its unique characteristics are suitable for various advanced food technologies. This review outlines recent developments in gellan gum production, modification, and newer applications focusing on food printing and bioactive delivery applications, in the last three years. The yield and production condition of gellan gum is a major factor that affects the cost and its applications. Moreover, modified Gellan gum has been shown to have superior characteristics and functionality as compared to native one. The viscosifying, thermosensitive, gelling etc. characteristics of gellan gum makes it an crucial ingredient in case of preparation of 3D printing ink. Further, gellan gum is also found to be important wall material in case of bioactive delivery application through encapsulation. Optimized methods of production, sustainable feedstock, and stress conditions are critical for the desired functionality and yield of the Gellan gum.

Sustainability in the Production of Gellan Gum From Sphingomonas Species by Using the Best Optimum Conditions: Review

AbstractMultiple exo-polysaccharides derived from microorganisms have been documented within the previous decade, encompassing their distinct structural and functional characteristics. Gellan gum represents one of these emerging biopolymers, exhibiting versatile properties. However, the production of gellan gum is hindered by low yields, costly downstream procedures, and an overwhelmingly high market demand, rendering it a material of elevated expense. Consequently, it is advantageous to comprehend the diverse approaches available for the development of a cost-effective bioprocess specifically tailored for gellan gum. This comprehensive analysis centers on elucidating the intricacies of the upstream and downstream methodologies employed in gellan gum production, adopting an industrial standpoint. An exhaustive examination of the functional disparities between the two variants of gellan gum is undertaken, focusing on aspects such as hydration, gelation, stability, and texture. This research investigates the quantities of gellan gum generated from various species ofSphingomonasbacteria, while also examining the optimal conditions through the utilization of agricultural waste as substitutes for the production medium, with the aim of enhancing the output of the product and subsequently diminishing the production expenses.

Characterization and optimization of gellan gum production by natural Sphingomonas sp. SM2

Gellan is one of the most important industrial microbial exopolysaccharides used for a wide range of applications in food, pharmaceutical, and oil. In this study, a native strain of Sphingomonas producing gellan gum was identified from rice roots. Various factors, including carbon and nitrogen sources, pH levels, fermentation duration, and aeration, were investigated to enhance the production of gellan by Sphingomonas sp. SM2. The highest efficiency in gum production was achieved by a medium composed of 30 g/L glucose. When the carbon-to-nitrogen ratio was 30, organic nitrogen caused this increase. By incorporating all relevant factors, the optimized fermentation process can yield a gum concentration of 8.64 ± 0.34 g/L. The total carbohydrate content of the native gum was found to be 52.62 ± 0.52%. The existence of mucilage surrounding the bacterial cells was verified by scanning electron microscopy images. The extracted gellan gum was characterized using FTIR, 1H NMR, and HPLC analyses. The structure of the gum was confirmed by comparing it with the standard gellan gum. The production of gellan gum by Sphingomonas sp. SM2 using the utilization of diverse carbon sources suggests its immense potential as a gellan producer.

Sugarcane juice is an effective feedstock for the production of gellan gum: process development and characterization

Sugarcane juice is an effective feedstock for the production of gellan gum: process development and characterization

Mutagenesis enhances gellan gum production by a novel Sphingomonas spp.: upstream optimization, kinetic modeling, and structural and physico-functional evaluation.

Gellan gum (GG) has gained tremendous attention owing to its diversified applications. However, its high production and hence market cost are still a bottleneck in its widespread utilization. In the present study, high GG producing mutant of Sphingomonas spp. was developed by random mutagenesis using ethyl methylsulphonate (EMS) for industrial fermentation and identified as Sphingomonas trueperi after 16S rRNA and matrix-assisted laser desorption/ionization-time of flight mass spectrometry (MALDI-TOF-MS) analysis. The fermentation conditions such as pH, temperature, and inoculum ratio were optimized by one factor at a time (OFAT) followed by screening of medium components by the Plackett-Burman statistical design. The most critical nutrients were further optimized by response surface methodology for maximizing GG production. The effect of dissolved oxygen tension in bioreactor on cell growth, substrate consumption, GG production, and batch productivity was elucidated. The highest GG titer (23 ± 2.4g/L) was attained in optimized medium at 10% inoculum (6.45 ± 0.5 log cfu/mL) under controlled fermentation conditions of pH (7), temperature (30°C), agitation (300-600rpm), and aeration (0.5-2.0 SLPM) at 22 ± 2% dissolved oxygen tension in a 10-L bioreactor. Kinetic modeling of optimized batch process revealed that logistic growth model could best explain biomass accumulation, while GG formation and substrate consumption were best explained by Luedeking-Piret and exponential decay model, respectively. Structural and physico-functional features of GG produced by mutant Sphingomonas spp. were characterized by HPLC, FTIR, NMR, DSC, TGA, GPC, SEM, and rheological analysis. The higher productivity (0.51g/L/h) under optimized fermentation conditions suggests potential consideration of mutant and process for commercial utilization.

Effects of organic and inorganic nitrogen sources on the transcriptome of gellan gum biosynthesis by Sphingomonas paucimobilis.

Investigate the effects of different nitrogen sources on the metabolic characteristics of Sphingomonas paucimobilis during gellan gum (GG) production was helpful for developing optimized conditions that are widely applicable to all GG production processes. We compared the effects of organic nitrogen (ON) and inorganic nitrogen (IN) sources during GG production using transcriptome sequencing. Our results showed that compared with the IN source, the ON source effectively improved the cell number and GG production of S. paucimobilis during fermentation. There were significant differences in gene transcription levels between the ON and IN groups at different fermentation times. The transcriptional levels of multiple genes in the pathways from α-D-glucose-1P to glyceraldehyde-3P were reduced in the ON group, whereas those of multiple genes in the pathways from glyceraldehyde-3P to acetyl-CoA were significantly enhanced in the ON group after 12 h of fermentation. The transcription levels of multiple genes participating in the citrate cycle and upstream of fatty acid metabolism pathways were significantly enhanced in the ON group after 12 h of fermentation. Except for the transcripts per million (TPMs) of pgm and rfbA genes in ON, which were significantly higher than those in IN at 12 h after fermentation, the TPMs of the majority of genes in ON were significantly lower than those in IN. The transcription levels of genes participating in the transformation of N-acetyl-D-glucosamine (GlcNAc) to UDP-N-acetyl-alpha-D-glucosamine (UDP-GlcNAc) were enhanced in the ON group during the fermentation process.

Gellan gum biopolymer- A review

Gellan gum is an anionic polysaccharide produced by the bacterium Sphingomonas paucimobilis. Kaneko and Kang discovered the biopolymer in the laboratory of the Kelco Division of Merck and Co., California, USA. It is composed of tetrasaccharide repeating units of two residues of D-glucose, one of D-glucuronic and one of L-rhamnose. The functional properties of gellan gum make it one of the industrially useful exopolysaccharides. Sphingomonas paucimobilis ATCC 31461 is the bacterium used for the industrial production of gellan gum. The gellan gum has potential applications in food, pharmaceutical, biomedical and other industries. The gellan gum finds uses in the bioremediation field. Bioaugmentation of contaminated aquifers, biodegradation of hydrocarbons and the removal of dyes from wastewater are a few of its applications. This review provides an overview of the characteristics, production of gellan gum and recent bioremediation applications.

Optimization of cultural conditions of gellan gum production from recombinant Sphingomonas paucimobilis ATCC 31461 and its characterization

Optimization of cultural conditions of gellan gum production from recombinant Sphingomonas paucimobilis ATCC 31461 and its characterization

Grape pomace as a promising source for gellan gum production

The aim of the present study was to determine the potential use of grape pomace, local agricultural waste, as a sole carbon source in the production of gellan gum. For this purpose, optimization of fermentation conditions of Sphingomonas paucimobilis (ATCC 31461) to produce gellan gum with the maximum yield was studied. This study clearly confirmed that gellan yield depended on carbon source concentration, bacterial inoculum volume and mixing rate. Maximum yield was found as 12.08 g/L at 5% carbon ratio, 4% inoculum volume and mixing rate at 300 rpm. The conversion ratio of waste product into gellan gum was identified as 0.24 gellan gum/grape pomace (g/g). Commercial gellan gum samples had glucose:rhamnose:glucuronic acid ratio as around 2.6:1.15:1, while biosynthesized gellan gum had 2.6:0.5:1 which indicated the effect of carbon source on chemical composition of gelllan gum. The molecular weights of biosynthesized and commercial gellan were determined as 6.88 × 105, 1 × 106, respectively. FTIR and 1H NMR spectral analysis were applied for the purpose of clarifying structures of polymers. Regarding the rheological properties, Herschel–Bulkley model better described the flow behavior of the gum solutions. The commercial gellan gum showed higher viscosity than the biosynthesized gellan. Rheological properties of polymer were affected by changes in the acyl substitution. The biosynthesized gellan from grape pomace showed better stability against temperature changes than commercial gellan gum.

Cloning and expression of gellan gum biosynthetic genes gelQ, gelB, gelL and gel K of Sphingomonas paucimobilis, production and characterization of the recombinant gellan gum

Abstract Gellan gum, a linear exopolysaccharide produced by Sphingomonas paucimobilis, is one of the most multifunctional polymers used in food, cosmetics and pharmaceutical industries. In the present study, for the first time, the gellan gum biosynthetic genes gel Q, gel B, gel L and gel K of Sphingomonas paucimobilis were cloned and successfully expressed in the same bacterium using the vector, pBBR122. The recombinant proteins were purified using Ni-NTA column chromatography and the molecular weight was predicted using SDS-PAGE. The biomass and gellan gum production of the strains harboring the expressed genes were analyzed in a laboratory fermentor and the production was higher with recombinant gel Q gene (Biomass: 7.03 ± 0.1 g/l; Gellan gum: 11.71 ± 0.2 g/l) compared to recombinant strains expressed with gel B, gel K and gel L genes. The optimum gellan gum production was obtained at 30 °C, pH 6.5, 400 rpm agitation speed, 90% Dissolved oxygen level and carbon-nitrogen ratio 3. The viscosity of polymer decreased with an increased shear rate which substantiates the use of this exopolysaccharide as a better gelling and thickening agent. The glucose: glucuronic acid: rhamnose ratio of the recombinant polymer was around 2:1:1 which is similar to the structural property of its native gellan. Different shapes like disc, membrane, fibres, particles and beads of gellan were made which may have wide applications in tissue engineering and drug delivery. The water holding capacity of the gellan gum gel was maximum in 100 mM calcium and minimum in gel with 5 mM Ca2+at 60 min. Compression test results illustrated that there was no significant change in the textural property of the recombinant gellan for different storage intervals compared to native gellan.

Production of gellan gum using milk skin residue (MSR)—a tea shop waste: statistical optimization and downstream processing

In this work, the production and downstream processing of gellan gum obtained from milk skin residue (MSR) as a carbon source was investigated. The different medium variables, namely shaking speed, inoculum size, and nitrogen source, on gellan gum production were studied. The suitable medium variables were found to be shaking speed (150 rpm); inoculum size (5% v/v), and nitrogen source (yeast extract, YE). The production of gellan gum was compared for various carbon sources, namely fructose, sucrose, glucose, lactose, and MSR. In order to obtain higher gellan gum concentration, response surface methodology was employed for optimizing MSR to glucose ratio, initial pH, and yeast extract concentration. The maximum gellan gum concentration of 8.98 ± 0.42 g/L was obtained at the following optimum conditions: ratio of MSR and glucose = 1:0.743, initial pH (7.5), and yeast extract concentration 8 g/L. The concentration of gellan gum was increased by 2.73-fold than un-optimized medium. The various factors influencing the recovery of gellan gum, namely screening of solvents, ratio of solvent to supernatant (v/v), and incubation time for precipitation, were also studied. The purified gellan gum was characterized by thermogravimetric analysis (TGA/DSC), Fourier transform infrared spectroscopy, scanning electron microscope, and X-ray diffraction analysis.

Improved gellan gum production by a newly-isolated Sphingomonas azotifigens GL-1 in a cheese whey and molasses based medium

Gellan gum is a water-soluble exopolysaccharide, it has applications in the food, pharmaceutical and chemical industries. In this study, a gellan gum producing strain was isolated from rice root, and this strain was identified be the species of Sphingomonas azotifigens. The Plackett-Burman design was applied to investigate the main factors affecting gellan gum production by S. azotifigens GL-1 in a molasses and cheese whey based medium; the medium compositions were optimized by response surface methodology. The optimum cheese whey based medium consisted of cheese whey 68.34 g/L, Na2HPO4 14.58 g/L and KH2PO4 7.66 g/L, and the maximum gellan gum production that using this medium was 33.75 ± 1.55 g/L. 14.75 ± 0.65 g/L gellan gum was obtained with an optimized molasses medium, which consisted of molasses 50 g/L, Na2HPO4 9.71 g/L and KH2PO4 5.92 g/L. The molecular weight of gellan gum obtained from two medias were 1.06 × 106 and 0.89 × 106 Da, respectively. The cheese whey-derived gellan gum showed a higher rhamnose, lower glucuronic acid and higher glycerate content compared to the molasses-derived gellan gum. S. azotifigens GL-1 has a high gellan gum production capacity in a cheap medium suggesting it has great potential as an industrial gellan gum producer.

The mechanism of improved gellan gum production by two-stage culture of Sphingomonas paucimobilis.

A two-stage culture (with controlled sucrose concentrations and temperatures) of Sphingomonas paucimobilis for gellan gum production has been previously investigated. Herein, the mechanism of a two-stage culture favoring gellan gum overproduction was revealed by analysing the cell-membrane permeability and the proteomics for gellan gum biosynthesis. The two-stage culture, resulted in 79.8% increased content of unsaturated fatty acids, and 3.95% increased ratio of unsaturated to saturated fatty acids in the cell membrane. Moreover, cell membrane permeability increased and thus further enhanced gellan gum biosynthesis. Proteomic analysis results indicated that 13 identified protein spots were involved in energy generation, glycogen biosynthesis, and glycolysis. These findings revealed that two-stage culture impellel carbon flux flow toward gellan gum biosynthesis.

Cost-effective optimization of gellan gum production by Sphingomonas paucimobilis using corn steep liquor

Gellan gum, produced by Sphingomonas paucimobilis, is increasingly used in food and pharmaceutical industries as stabilizing, emulsifying, texturing and gelling agents. However, its high production costs may limit its full commercial potential. Therefore, in this study, we investigated ways to reduce gellan gum production costs and improve yields. We first revealed corn steep liquor (CSL) as a cost-effective nutrient source that can improve gellan gum yields. We then systematically optimized culture conditions even further, and revealed that the addition of Triton X-100 surfactant and selected inorganic nitrogen sources improved gellan gum production. Under our optimized conditions (glucose 33.75 g/L, CSL 10 g/L, urea 2.5 g/L, MgSO4 1.08 g/L, KH2PO4 3.24 g/L, K2SO4 1 g/L and Triton X-100 0.75 g/L), we yielded a maximum concentration of 14.41 g/L, which was about 1.5-fold higher than non-optimized CSL-based medium. Our findings highlight the use of CSL as a cost effective and promising nutrient source for industrial production of gellan gum.

A Carotenoid- and Poly-β-Hydroxybutyrate-Free Mutant Strain of Sphingomonas elodea ATCC 31461 for the Commercial Production of Gellan.

Gellan gum is a microbial exopolysaccharide, produced after aerobic fermentation using the Gram-negative bacterium strain Sphingomonas elodea ATCC 31461. Due to its unique structure and excellent physical characteristics, gellan gum has a broad range of applications in food, pharmaceutical, and other industries where it is used for stabilizing, emulsifying, thickening, and suspending. During the fermentative production of gellan, strain ATCC 31461 also accumulates large amounts of the metabolic by-products yellow carotenoid pigments and poly-β-hydroxybutyrate (PHB), which is decreasing the gellan production and increasing processing costs. A pigment PHB-free mutant was obtained by knocking out the phytoene desaturase gene (crtI) in the carotenoid biosynthetic pathway and the phaC gene, encoding a PHB synthase for the polymerization of PHB. Unfortunately, the double gene knockout mutant produced only 0.56 g liter-1 gellan. Furthermore, blocking PHB and carotenoid synthesis resulted in the accumulation of pyruvate, which reduced gellan production. To elevate gellan production, combined UV irradiation and ethyl methanesulfonate (EMS) mutagenesis treatment were used. A mutant strain with the same level of pyruvate as that of the wild-type strain and higher gellan production was isolated (1.35 g liter-1, 132.8% higher than the double gene knockout mutant and 14.4% higher than the wild-type strain ATCC 31461). In addition, a new gellan gum recovery method based on the new mutant strain was investigated, in which only 30% isopropanol was required, which is twice for the wild-type strains, and the performance of the final product was improved. Thus, the mutant strain could be an ideal strain for the commercial production of gellan.IMPORTANCE A carotenoid- and PHB-free double gene knockout strain mutant was constructed to simplify the purification steps normally involved in gellan production. However, the production of gellan gum was unexpectedly reduced. A mutant with 14.4% higher gellan production than that of the wild-type strain was obtained and isolated after employing UV and EMS combined mutagenesis. Based on this high-yield and low-impurity-producing mutant, a new recovery method requiring less organic solvent and fewer operating steps was developed. This method will effectively reduce the production costs and improve the economic benefits of large-scale gellan production.

Phyre 2 and I-Tasser web portal for Protein modeling, Prediction and Validation of gel Q and gel K genes from gellan gum producing bacterial strain Sphingomonas paucimobilis ATCC 31461

Gellan gum, an anionic, high-molecular-weight, hetero exo-polysaccharide produced by Sphingomonas paucimobilis ATCC 31461 has potential applications in food and pharmaceutical industries, as a gelling agent, a highly-viscous biogum, a stabilizing agent etc. Three dimensional structure of a protein encoded by a gene could be useful to identify the function of the gene. This study investigates about the 3-D structure prediction of gel Q and gel K protein of Sphingomonas paucimobilis ATCC 31461 using two different protein modeling tools, Phyre2 and I-Tasser. Amplified gel Q and gel K genes were sequenced and the template protein structure identification was carried out using BLASTp with PDB. Superpositioning of the model with the template was analyzed with PyMol. Structure Validation servers of RAMPAGE, PROSA, Verify 3D, ERRAT and Qmean endorsed the 3D structure. The Phyre2 and I-Tasser model of gel Q protein showed best probability conformation with 94.3% and 80.7% residue respectively in the core region of Ramachandran plot showing greater accuracy of model prediction compared to gel K protein with 92.3% and 78.6% residue for Phyre2 and ITasser models respectively. Phyre2 server generated a finer prediction, analysis and validation for gel Q and gel K protein structure than the I-Tasser server. The results generated using Expasy tool also suggested that glycosyl transferase protein, encoded by the genes gel Q and gel K in the gel cluster may be directly involved in the fourth sugar addition of the repeating unit and in the incorporation of GlcA from UDP-glucuronic acid, into glucosyl-α-pyrophosphorylpolyprenol intermediate respectively. In order to develop a recombinant Sphingomonas paucimobilis ATCC 31461, gel Q and gel K gene might be a powerful successor for the overexpression of the gene to enhance gellan gum production.

Production of Gellan Gum by Sphingomonas paucimobilis on Crude Sweet Whey Using Different Bioreactor Feeding Strategies

Aims: Production of gellan gum by Sphingomoas paucimobilis from whey was optimized by different fermentation techniques.
 Study Design: Study the growth behavior of Sphingomoas paucimobilis was cultivated on 40% sweet whey medium in the bioreactor as a batch, fed batch and continuous culture and effect of aeration and agitation speed on gellan production.
 Place and Duration of Study: Microbiology Dept., Fac. of Agriculture, Ain Shams Univ., Cairo, Egypt, 2016/ 2017.
 Methodology: Using Sphingomoas paucimobilis on sweet whey in the bioreactor as a batch, fed batch (pulsed & continuous) and continuous culture. Among the four levels of air saturation and four levels of agitation speeds.
 Results: Using the continuous feeding of sugar sweet whey at 1.53 gl-1h-1during 12 h was favorable than pulsed feeding for gellan production in fed-batch culture. In continuous culture addition of 40% SW at 0.055 h-1 dilution rate (110 ml h-1), the values of gellan parameters recorded by Sphingomoas paucimobilis were 24.34%, 26.54% & 0.337 gl-1h-1 for gellan yield, conversion coefficient and gellan productivity during 24 h. At 28ºC. This technique increments the gellan production (gl-1h-1) by 3.3 & 2.2-2.5 and 1.5- 1.6 fold as compared to that produced by using batch & fed- batch pulsed and fed-batch continuous techniques respectively. The emulsifying capability of the partially purified gellan was 100% whereas it was 95% for xanthan gum, as well as its high flocculating activity than xanthan. A tough worm-like gel or firm gel were formed when 10% calcium chloride solution or 0.5 g sodium chloride were added to gellan solution.
 Conclusion: The maximum gellan yield and lower fermentation period were obtained with air saturation of 60% at 750 rpm agitation speed. The continuous feeding at 1.53 gl-1h-1 was favorable than pulsed feeding for gellan production in fed-batch culture, while the maximum gellan productivity was obtained by using a continuous culture technique at 0.055 h-1 dilution rate.

Production of gellan gum, an exopolysaccharide, from biodiesel-derived waste glycerol by Sphingomonas spp.

In the present study, biodiesel-derived waste glycerol (WG) was used for the isolation and production of gellan, an exopolysaccharide, on media containing WG as the main carbon source. Two bacterial isolates showed gellan producing potential which were identified as Sphingomonas pseudosanguinis (Accession No. GI:724472387) and Sphingomonas yabuuchiae (GI:724472388) by 16S rRNA gene sequencing. To maximize gellan production by S. pseudosanguinis and S. yabuuchiae, media optimization was performed at different pHs and glycerol concentrations. Morphological observations through microscopic images showed the production of gellan from these isolates. Simple linear regression showed better utilization of WG by S. pseudosanguinis than S. yabuuchiae at pH 6 and pH 7. Though, both the strains showed reverse trend at pH 8. Both the strains were able to produce high amounts of gellan gum (51.6 and 52.6g/l, respectively) using WG (80g/l) as the sole carbon source, in a minimal medium. This is the first report on the efficient degradation of WG and low-cost production of gellan. Owing to these characteristics, S. pseudosanguinis and S. yabuuchiae demonstrate great potential for use in the commercial production of gellan and in the bioremediation of WG.

Bacterial Production of Gellan Gum as a Do-It-Yourself Alternative to Agar.

Lack of access to reagents and equipment can make performing microbiology experiments difficult in K-12 classrooms and do-it-yourself (DIY) science settings. We demonstrate how the bacterium Sphingomonas paucimobilis can be used to synthesize gellan gum, an alternative to agar, with materials available to DIY scientists and educators. The method involves microwaving cultures of S. paucimobilis after a two-step growth procedure, supplementing them with additional media components as necessary, and then pouring plates. Gellan gum produced in the S. paucimobilis culture acts as a solidifying agent and provides a resilient surface that supports growth of microbes, including Escherichia coli and Saccharomyces cerevisiae. This procedure offers a unique opportunity to experiment with microbial production of an extracellular polysaccharide and to cheaply and sustainably source a reagent for research.

Biovalorization of Olive Mill Waste Water for the Production of Gellan Gum from Sphingomonas paucimobilis

Biovalorization of Olive Mill Waste Water for the Production of Gellan Gum from Sphingomonas paucimobilis