Fermentation optimization, characterization and bioactivity of exopolysaccharides from Funalia trogii

Bioflocculation of pollutants in wastewater using flocculant derived from Providencia huaxiensis OR794369.1

BACKGROUND

Water pollution has become a major environmental and health concern due to increasing population and industrialisation. Microbial flocculants are promising agents for treatment of contaminated water owing to their effectiveness, eco-friendliness, and high biosafety levels. In this study, culture conditions of Providencia huaxiensis OR794369.1 were optimised and its bioflocculant was extracted, characterised and used to treat wastewater.

RESULTS

The maximum flocculating activity of 92% and yield of 3.5 g/L were obtained when cultivation conditions were: 3% inoculum size, starch, casein, initial pH of 6, cultivation temperature of 30 oC and 72 h of fermentation. The bioflocculant is an amorphous glycoprotein biomolecule with 37.5% carbohydrates, 27.9% protein, and 34.6% uronic acids. It is composed of hydroxyl, amino, alkanes, carboxylic acid and amines groups as its main functional structures. It was found to be safe to use as it demonstrated non-cytotoxic effects on bovine dermis and African green monkey kidney cells, illustrating median inhibitory concentration (IC50) values of 180 and > 500 µg/mL on both cell lines, respectively. It demonstrated the removal efficiencies of 90% on chemical oxygen demand (COD), 97% on biological oxygen demand (BOD) and 72% on Sulphur on coal mine wastewater. It also revealed the reduction efficacies of 98% (COD) and 92% (BOD) and 70% on Sulphur on domestic wastewater.

CONCLUSION

The bioflocculant was effective in reducing pollutants and thus, illustrated potential to be used in wastewater treatment process as an alternative.

Isolation and Optimisation of Culture Conditions for a Marine Bioflocculant-Producing Bacterium and Application of Its Bioflocculant in Wastewater Treatment

The application of bioflocculants has become an alternative to that of chemical flocculants in wastewater treatment due to their environmental friendliness and non-toxic effects. This study aimed at isolating a bioflocculant-producing bacterium from marine water, optimisation of its culture conditions, and investigation of the removal efficiency of its bioflocculant on pollutants in wastewater. The bacterium was identified by 16S rRNA gene analysis. Optimal carbon and nitrogen sources, inoculum size, temperature, pH, and time were determined by the one-factor-at-a-time assay. The cytotoxicity of the bioflocculant was assessed on African green monkey kidney and bovine dermis cells using a tetrazolium-based columetric (MTT) method. Its removal efficiencies on chemical oxygen demand (COD), biological oxygen demand (BOD) and sulphur were determined using the Jar test method. The bacterial isolate was identified as Ochrobactrum oryzae AB84113. A maximum flocculating activity of 92% and a yield of 3.768 g/L were obtained when a 1% (v/v) inoculum size was used in the presence of starch and yeast extract at pH 7, 30 °C, and after 72 h of cultivation. The bioflocculant demonstrated non-cytotoxic effects on bovine dermis and African green monkey kidney cells. The bioflocculant removed 98% COD, 91% BOD and 86% of Sulphur. The bioflocculant has potential for pollutant removal from industrial wastewater.

Haploid Genome Analysis Reveals a Tandem Cluster of Four HSP20 Genes Involved in the High-Temperature Adaptation of Coriolopsis trogii

Coriolopsis trogii is a typical thermotolerant basidiomycete fungus, but its thermotolerance mechanisms are currently unknown. In this study, two monokaryons of C. trogii strain Ct001 were assembled: Ct001_29 had a genome assembly size of 38.85 Mb and encoded 13,113 genes, while Ct001_31 was 40.19 Mb in length and encoded 13,309 genes. Comparative intra- and interstrain genomic analysis revealed the rich genetic diversity of C. trogii, which included more than 315,194 single-nucleotide polymorphisms (SNPs), 30,387 insertion/deletions (indels), and 1,460 structural variations. Gene family analysis showed that the expanded families of C. trogii were functionally enriched in lignocellulose degradation activities. Furthermore, a total of 14 allelic pairs of heat shock protein 20 (HSP20) genes were identified in the C. trogii genome. The expression profile obtained from RNA sequencing (RNA-Seq) showed that four tandem-duplicated allelic pairs, HSP20.5 to HSP20.8, had more than 5-fold higher expression at 35°C than at 25°C. In particular, HSP20.5 and HSP20.8 were the most highly expressed HSP20 genes. Allelic expression bias was found for HSP20.5 and HSP20.8; the expression of Ct29HSP20.8 was at least 1.34-fold higher than that of Ct31HSP20.8, and that of Ct31HSP20.5 was at least 1.5-fold higher than that of Ct29HSP20.5. The unique structural and expression profiles of the HSP20 genes revealed by these haplotype-resolved genomes provide insight into the molecular mechanisms of high-temperature adaptation in C. trogii. IMPORTANCE Heat stress is one of the most frequently encountered environmental stresses for most mushroom-forming fungi. Currently available fungal genomes are mostly haploid because high heterozygosity hinders diploid genome assembly. Here, two haplotype genomes of C. trogii, a thermotolerant basidiomycete, were assembled separately. A conserved tandem cluster of four HSP20 genes showing allele-specific expression was found to be closely related to high-temperature adaptation in C. trogii. The obtained haploid genomes and their comparison offer a more thorough understanding of the genetic background of C. trogii. In addition, the responses of HSP20 genes at 35°C, which may contribute to the growth and survival of C. trogii at high temperatures, could inform the selection and breeding of elite strains in the future.

Production, characterization, and bioactivities of exopolysaccharides from the submerged culture of Ganoderma cantharelloideum M. H. Liu

In this study, the submerged culture conditions for exopolysaccharide (EPS) production by Ganoderma cantharelloideum M. H. Liu were screened and optimized, and the physicochemical and biological properties of EPS were investigated. Results showed that the glucose and tryptone were the best C and N sources for the maximum EPS production, respectively. Under the optimal culture conditions, the EPS production achieved 1.60 g/L at day 6 in a 5 L stirred tank reactor. Two purified fractions (i.e., Fr-I and Fr-II) were obtained from the G. cantharelloideum EPS by gel permeation chromatography. Fr-II had a higher yield (87.54%), carbohydrate (95.86%), and protein (3.07%) contents and lower molecular weight (74.56 kDa) than that of Fr-I. Both Fr-I and Fr-II were polysaccharide-protein complexes with different monosaccharide compositions and chemical structures. Fr-II also exhibited stronger radical scavenging abilities, antioxidant capacities, and α-amylase and α-glycosidase inhibitory activities in vitro than that of Fr-I. Therefore, Fr-II obtained from G. cantharelloideum EPS might be explored as potential natural functional components or supplements for applications in food, medicine, and cosmetics.

Bacteria-assisted biogreen synthesis of radical scavenging exopolysaccharide-iron complexes: an oral nano-sized nutritional supplement with high in vivo compatibility

Microbial exopolysaccharides (EPSs) have recently served as an efficient substrate for the production of biocompatible metal nanoparticles (NPs) given their favorable stabilizing and reducing properties due to the presence of polyanionic functional groups in their structure. In the present work, Pantoea sp. BCCS 001 GH was used to produce EPS-stabilized biogenic Fe NPs as a complex through a novel biosynthesis reaction. Physicochemical characterization of the EPS-Fe complex was performed, indicating high thermal stability, desirable magnetic properties due to the uniform distribution of the Fe NPs with the average size of ∼10 nm and spherical shape within the EPS matrix. In addition, the in vivo toxicity of the EPS-stabilized Fe NPs was evaluated to investigate their potential for the treatment of iron deficiency anemia. Biological blood parameters and organ histology studies confirmed very high safety of the biosynthesized composite, making EPS-Fe a suitable candidate with an economical and environment friendly synthesis method for a wide spectrum of potential fields in medicine.

Exopolysaccharides from Basidiomycota: Formation, isolation and techno-functional properties

This Mini Review gives an overview of and respective references for the production and properties of exopolysaccharides from Basidiomycota in submerged cultivation. Media and conditions that are usually applied in laboratory culture are summarized, and the lack of studies related to up-scaling is addressed. Procedures for isolation and purification of the exopolysaccharides from the fermentation media are reviewed, and challenges related to exopolysaccharide quantification are discussed. Finally, the techno-functional properties of the respective exopolysaccharides, and potential applications in foods are addressed.

Optimization of EPS Production and Characterization by a Halophilic Bacterium, Kocuria rosea ZJUQH from Chaka Salt Lake with Response Surface Methodology

With the rising awareness of microbial exopolysaccharides (EPSs) application in various fields, halophilic microorganisms which produce EPSs have received broad attention. A newly identified Kocuria rosea ZJUQH CCTCC M2016754 was determined to be a moderate halobacterium on account of its successful adaption to the environment containing 10% NaCl. The optimal combination of fermentation medium compositions on EPS production was studied. In this work, a fractional factorial design was adopted to investigate the significant factors that affected EPS production. The factors of KCl and MgSO₄ were found to have a profound impact on EPS production. We utilized central composite design and response surface methodology to derive a statistical model for optimizing the submerged culture medium composition. Judging from these experimental results, the optimum culture medium for producing EPSs was composed of 0.50% casein hydrolysate, 1.00% sodium citrate, 0.30% yeast extract, 0.50% KCl, 0.50% peptone, and 5.80% MgSO₄ (initial pH 7.0). The maximal EPS was 48.01 g/L, which is close to the predicted value (50.39 g/L). In the validation experiment, the highest concentration of 70.64 g/L EPSs was obtained after 120 h under the optimized culture medium in a 5-L bioreactor. EPS from this bacterium was also characterized by differential scanning calorimetry (DSC) and Fourier transform infrared analysis (FT-IR). The findings in this study imply that Kocuria rosea ZJUQH has great potential to be exploited as a source of EPSs utilized in food, the pharmaceutical and agriculture industry, and in the biotreatment of hypersaline environments.

Effect of Tween 80 and Acetone on the Secretion, Structure and Antioxidant Activities of Exopolysaccharides from Lentinus tigrinus

In this study, the effects of the addition of Tween 80 and acetone on secretion, structure and antioxidant activities of Lentinus tigrinus exopolysaccharides (EPS) were investigated. It was found that Tween 80 and acetone displayed a stimulatory effect on EPS secretion. The EPS obtained by the addition of Tween 80 (EPS-T), acetone (EPS-A) and control (EPS--C) were purified by Sepharose CL-6B gel filtration chromatography and molecular mass of purified fractions was estimated to be 22.1, 137 and 12 kDa, respectively. Monosaccharide composition analysis indicated that EPS-T, EPS-A and EPS-C were mainly composed of glucose and mannose. Congo Red test indicated that EPS-T and EPS-A had a highly ordered conformation of triple helix, while EPS-C had a random coil conformation. Furthermore, EPS-A exhibited higher DPPH scavenging and antiproliferative activities than EPS--C and EPS-T, which might be attributed to the molecular mass.

Implications for public health demands alternatives to inorganic and synthetic flocculants: bioflocculants as important candidates

Chemical flocculants are generally used in drinking water and wastewater treatment due to their efficacy and cost effectiveness. However, the question of their toxicity to human health and environmental pollution has been a major concern. In this article, we review the application of some chemical flocculants utilized in water treatment, and bioflocculants as a potential alternative to these chemical flocculants. To the best of our knowledge, there is no report in the literature that provides an up‐to‐date review of the relevant literature on both chemical flocculants and bioflocculants in one paper. As a result, this review paper comprehensively discussed the various chemical flocculants used in water treatment, including their advantages and disadvantages. It also gave insights into bioflocculants production, challenges, various factors influencing their flocculating efficiency and their industrial applications, as well as future research directions including improvement of bioflocculants yields and flocculating activity, and production of cation‐independent bioflocculants. The molecular biology and synthesis of bioflocculants are also discussed.

Evaluation of flocculating performance of a thermostable bioflocculant produced by marine Bacillus sp

This study assessed the bioflocculant (named MBF-W7) production potential of a bacterial isolate obtained from Algoa Bay, Eastern Cape Province of South Africa. The 16S ribosomal deoxyribonucleic acids gene sequence analysis showed 98% sequence similarity to Bacillus licheniformis strain W7. Optimum culture conditions for MBF-W7 production include 5% (v/v) inoculum size, maltose and NH4NO3 as carbon and nitrogen sources of choice, medium pH of 6 as the initial pH of the growth medium. Under these optimal conditions, maximum flocculating activity of 94.9% was attained after 72 h of cultivation. Chemical composition analyses showed that the purified MBF-W7 was a glycoprotein which was predominantly composed of polysaccharides 73.7% (w/w) and protein 6.2% (w/w). Fourier transform infrared spectroscopy revealed the presence of hydroxyl, carboxyl and amino groups as the main functional groups identified in the bioflocculant molecules. Thermogravimetric analyses showed the thermal decomposition profile of MBF-W7. Scanning electron microscopy imaging revealed that bridging played an important role in flocculation. MBF-W7 exhibited excellent flocculating activity for kaolin clay suspension at 0.2 mg/ml over a wide pH range of 3-11; with the maximal flocculation rate of 85.8% observed at pH 3 in the presence of Mn(2+). It maintained and retained high flocculating activity of over 70% after heating at 100°C for 60 min. MBF-W7 showed good turbidity removal potential (86.9%) and chemical oxygen demand reduction efficiency (75.3%) in Tyume River. The high flocculating rate of MBF-W7 makes it an attractive candidate to replace chemical flocculants utilized in water treatment.

Bacillus toyonensis strain AEMREG6, a bacterium isolated from South African marine environment sediment samples produces a glycoprotein bioflocculant

A bioflocculant-producing bacteria, isolated from sediment samples of a marine environment in the Eastern Cape Province of South Africa demonstrated a flocculating activity above 60% for kaolin clay suspension. Analysis of the 16S ribosomal deoxyribonucleic acid (rDNA) nucleotide sequence of the isolate in the GenBank database showed 99% similarity to Bacillus toyonensis strain BCT-7112 and it was deposited in the GenBank as Bacillus toyonensis strain AEMREG6 with accession number KP406731. The bacteria produced a bioflocculant (REG-6) optimally in the presence of glucose and NH4NO3 as the sole carbon and nitrogen source, respectively, initial medium pH of 5 and Ca2+ as the cation of choice. Chemical analysis showed that purified REG-6 was a glycoprotein mainly composed of polysaccharide (77.8%) and protein (11.5%). It was thermally stable and had strong flocculating activity against kaolin suspension over a wide range of pH values (3-11) with a relatively low dosage requirement of 0.1 mg/mL in the presence of Mn2+. Fourier transform infrared spectroscopy (FTIR) revealed the presence of hydroxyl, carboxyl and amide groups preferred for flocculation. Scanning electron microscopy (SEM) revealed that bridging was the main flocculation mechanism of REG-6. The outstanding flocculating performance of REG-6 holds great potential to replace the hazardous chemical flocculants currently used in water treatment.

Immune activity of sweet potato (Ipomoea batatas L.) glycoprotein after enzymatic and chemical modifications

Immune activity of SPG-1 after its protein or carbohydrate portions modified by enzymatic or chemical treatments. Note: a and b: P < 0.01 and 0.05 compared with NC group, respectivily; c and d: P < 0.01 and 0.05 compared with untreated group, respectivily.

Extraction optimization and bioactivities of an extracellular polysaccharide produced by Aspergillus fumigatus

Aspergillus fumigatus produces an extracellular polysaccharide, AFEPS, when grew in NaOH solution pretreated rice-straw medium. A three-level, three-factor Box-Behnken design (BBD) response surface methodology (RSM) was applied to optimize the extraction parameters of AFEPS. RSM analysis indicated good correspondence between experimental and predicted values. The optimal conditions for polysaccharide were: precipitation time 10.9h, pH 5.2 and ethanol concentration 90%. AFEPS was composed of arabinose, xylose and glucose in a molar ratio of 1.05:5.36:10.83, its average molecular weight was estimated to be about 36.2kDa. Evaluation of the antioxidant activity in vitro suggested that AFEPS had high scavenging activity for superoxide anion and hydroxyl radicals. AFEPS exhibited excellent antitumor activities both in vitro and in vivo while showing no damage to normal cells.

Production of bioactive compounds with antitumor activity against sarcoma 180 by Pleurotus sajor-caju

This work studied the influence of culture medium composition and pH on exopolysaccharide (EPS) production by Pleurotus sajor-caju and validates the antitumor activity of the produced EPSs and of the mycelial biomass (intracellular polysaccharides [IPSs]) against Sarcoma 180 (S180) cells. The effect of the initial concentrations of (NH₄)₂SO₄, yeast extract and soy peptone on EPS production by P. sajor-caju was studied in shake flasks. A bioreactor was used to evaluate the pH values and the initial CaCO₃ and glucose concentrations. Extracts of EPSs (PE1) and IPSs obtained through two different separation processes (PM1 and PM2) were tested on mice inoculated with S180 cells. A medium containing 2.5, 1.0, and 1.0 g/L of (NH₄)₂SO₄, yeast extract and soy peptone, respectively, provided the highest EPS concentration (0.6 g/L). The use of pH 4.0, 1.0 g/L CaCO₃ and 20 g/L initial glucose concentration enhanced EPS productivity (3.84 g/L per hour). The PE1 extract promoted the highest reduction of S180 growth (86%), followed by the PM2 extract (80%); growth reduction was dose-independent for both substances. This work provides information about culture medium and conditions that enhanced the production of extracellular polysaccharides by P. sajor-caju. The results can contribute to the search for new bioactive products bringing novel aspects to the medical and pharmaceutical areas.