Salt Medium Research Articles

Prospective use of a cell‐free supernatant from the biosurfactant‐producing marine Planococcus maritimus SAMP MCC 3013 for oil removal and enhanced oil recovery

AbstractThe cell‐free supernatant (CFS) of the biosurfactant (BS) producing pure strain of Planococcus maritimus SAMP MCC 3013 was used for enhanced oil recovery (EOR). An indigenous marine culture of P. maritimus was grown in mineral salt medium (MSM) supplemented with glucose (1%) (w/v) (30°C, 120 rpm, 7 days). CFS was used to demonstrate its application for oil recovery through three assays: pumice stone, saturated gravel, and the glass beads‐packed column. The recovery of light paraffin oil was ∼40% in the pumice stone assay and ∼43% in the oil‐saturated gravel assay, respectively. The glass bead column demonstrated ∼42% of additional 2T engine oil recovery by CFS. Our study showed that BS containing CFS from P. maritimus SAMP MCC 3013 has the ability to recover oil in its crude form without using any sophisticated purification techniques. All three methods operated by us are harmonizing with each other with respect to the findings. Those methods can be employed in large scale operations for the bio‐recovery of oils using an environmentally friendly approach through the functional properties of BS. This is most likely the first report describing the use of a glass bead pack column for EOR applications particularly from Planococcus sp. These results are symbolic of prospective applications of BS containing CFS from indigenous P. maritimus SAMP MCC 3013 under ex‐situ conditions.

Ternary molten salt-assisted lignin pyrolysis for the co-production of monophenols and value-added carbon materials

In this paper, the ternary molten salt (Li2CO3-Na2CO3-K2CO3) was introduced into the lignin pyrolysis process for the co-production of monophenols and value-added carbon materials. The effect of lignin/molten salt ratios (i.e., 3:1, 1:1, and 1:3) on lignin pyrolysis behaviour was investigated herein. The pyrolytic products were characterized by gas chromatography–mass spectrometry, ultimate analyses, scanning electron microscopy, nitrogen adsorption analyses, and Raman analyses. Results showed that molten salt media can promote the conversion of bulky phenolic oligomers into mono-phenols by enhancing the cracking and deoxygenation reactions. P-type phenols (49.76 %) were produced when the lignin/molten salt mass ratio was 1:3. The porosity and aromaticity of biochar were regulated in-situ using molten salt. The possible catalytic effect of molten salt on lignin pyrolysis was proposed. This study provides a case reference for lignin waste resource utilization.

Expanding Pseudomonas taiwanensis VLB120's acyl-CoA portfolio: Propionate production in mineral salt medium.

As one of the main precursors, acetyl-CoA leads to the predominant production of even-chain products. From an industrial biotechnology perspective, extending the acyl-CoA portfolio of a cell factory is vital to producing industrial relevant odd-chain alcohols, acids, ketones and polyketides. The bioproduction of odd-chain molecules can be facilitated by incorporating propionyl-CoA into the metabolic network. The shortest pathway for propionyl-CoA production, which relies on succinyl-CoA catabolism encoded by the sleeping beauty mutase operon, was evaluated in Pseudomonas taiwanensis VLB120. A single genomic copy of the sleeping beauty mutase genes scpA, argK and scpB combined with the deletion of the methylcitrate synthase PVLB_08385 was sufficient to observe propionyl-CoA accumulation in this Pseudomonas. The chassis' capability for odd-chain product synthesis was assessed by expressing an acyl-CoA hydrolase, which enabled propionate synthesis. Three fed-batch strategies during bioreactor fermentations were benchmarked for propionate production, in which a maximal propionate titre of 2.8 g L-1 was achieved. Considering that the fermentations were carried out in mineral salt medium under aerobic conditions and that a single genome copy drove propionyl-CoA production, this result highlights the potential of Pseudomonas to produce propionyl-CoA derived, odd-chain products.

Characterization of bacteriocin produced by Brevibacillus laterosporus Tk3 isolated from ‘tatwakhar’ – a flour prepared from seeds of Aesculus indica in remote areas of Himachal Pradesh India

Bacteriocin producing strain Brevibacillus laterosporus TK3, was isolated from ‘Tatwakhar’- a flour prepared from seeds of Indian Horse Chestnut (Aesculus indica). Bacterial strain Brevibacillus laterosporus TK3 identified by morphological, biochemical techniques followed by 16S rRNA gene sequencing. The 16S rRNA sequence of bacteriocin producer was deposited in NCBI GenBank under accession no. KP861913.1. Bacteriocin of Brevibacillus laterosporus TK3 showed strong antagonistic activity against food spoiling/pathogenic bacteria viz. Listeria monocytogenes, Staphylococcus aureus and Clostridium perfringens. Bacteriocin production by Brevibacillus laterosporus TK3 was enhanced by optimizing production time, pH of the medium, inoculum size and incubation temperature. Maximum bacteriocin activity (6000 AU/ml) was recorded/obtained in basal salt medium of pH 5.5 with an inoculum size of 1.5 OD at 10% and incubation period of 24h at 35 °C. The bacteriocin was purified by single step gel exclusion chromatography. Molecular weight of active bacteriocin from Brevibacillus laterosporous TK3 was found to be 6 kDa according to SDS PAGE. The molecular mass of purified bacteriocin was confirmed as 5953.89 Da by MALDI TOF analysis. The purified bacteriocin was found desirable/suitable for food preservation as it showed wide spectrum of antimicrobial activity, resistance to high temperature, wide pH range and sensitivity to proteolytic enzymes thus, making it safe for human consumption.

Bioaugmentation of a novel bacterial consortium in cotton-planted soil for degradation of lambda-cyhalothrin

Extensive use of lambda-cyhalothrin (LC) for agricultural and domestic pest control leads to the accumulation of its residues in soil and water, which poses a serious threat to the environment. Remediation of LC at the point source is the most effective way to avoid its spread and harmful effects. Therefore, this study was planned to investigate the potential of indigenously isolated bacteria for the remediation of LC in cotton-vegetated soil. Three potent LC-degrading bacteria, Brucella intermedia Halo1, Alcaligenes faecalis CH1S, and Aquamicrobium terrae CH1T, were isolated from pyrethroid-contaminated soil. A consortium CHST comprising these strains was found to exhibit a higher potential for LC degradation as compared to the individual strains. The degradation of LC by CHST was optimized for four varying factors, i.e., pH, inoculum density (ID), carbon source (CS), and initial LC concentrations (PC), by applying the Taguchi design of experiments (DOE). The contribution of each factor to the biodegradation of LC was found in the order: pH > CS > PC > ID. The enhanced degradation of LC (84%) was attained at pH 7.0 in minimum salt medium (MSM) containing 10 mg/L LC and 3% inoculum. The consortium CHST was also augmented in sterilized and un-sterilized soil microcosms at three initial LC concentrations, i.e., 2, 5, and 10 mg/Kg. After 21 days of incubation, complete LC degradation was achieved at 2 mg/Kg initial concentration in sterilized as well as un-sterilized soil, whereas at higher concentrations, the extent of degradation was comparatively less. At 5 mg/Kg, 88 and 96% LC-degradation was observed in sterilized and un-sterilized soil respectively, compared to 79 and 90% degradation at 10 mg/Kg. During biodegradation, the major metabolite of LC, i.e., 3-phenoxybenzoic acid (3-PBA), was formed and further degraded. In the cotton-planted soil spiked with 10 mg/Kg LC, the consortium degraded 91.8% LC as well as improved the agronomic parameters of the cotton plant. In a nutshell, the consortium CHST was found to be a promising candidate for the remediation of LC contaminants at the point source.

Application of bio-metal-organic framework-based magnetic dispersive solid phase extraction for the extraction of polycyclic aromatic hydrocarbons from pasteurized milk

This work describes the development of a magnetic dispersive solid phase extraction method based on using bio–metal–organic framework (prepared from vitamin B3 and cobalt salt in water medium) as an efficient sorbent for the extraction of polycyclic aromatic hydrocarbons from milk samples. Briefly, the synthesized sorbent at mg–level is added to the supernatant phase after precipitating the proteins of milk sample and the mixture is vortexed. In the presence of magnetic field, the supernatant is removed and the sorbent particles containing the adsorbed analytes are eluted by using an appropriate organic solvent. The eluted analytes are more enriched using a magnetic ionic liquid–based dispersive liquid–liquid microextraction. After back–extraction of the analytes into n–hexane, the analytes are determined using gas chromatography–mass spectrometry. The experimental variables influencing the suggested method efficiency such as zinc sulfate solution concentration and volume, and vortexing time in proteins precipitating step, sorbent amount, adsorption time, ionic strength, elution solvent type and volume, desorption time, extraction solvent type and volume, and back–extraction solvent type, volume and time in extraction procedure were optimized by one parameter at a time strategy. Under the optimum conditions, low limits of detection (38–78 ng L−1) and quantification (130–260 ng L−1), high extraction recoveries (58–82%) and enrichment factors (145–205), and good precision (relative standard deviations ≤6.1%) were obtained. Finally, the developed method was effectively employed for quantification of polycyclic aromatic hydrocarbons in pasteurized milk samples.

Isolation, Characterization and Screening of Potential Lambda-Cyhalothrin-Degrading Bacteria from Cultivated Soil in Moro, Kwara State, Nigeria

The indiscriminate use of Lambda Cyhalothrin (LC), one of the commonly used synthetic pyrethroids (SPs) insecticides in agriculture, has led to the contamination of different environments with potentially serious impacts on the health of humans and animals. This study investigated the presence of LC-degrading bacteria in cultivated soils. Bacteria were isolated from agricultural soil on mineral salt medium (MSM) using an enrichment technique. They were characterized and identified. Their growth in different concentrations (50 mg/L, 75 mg/L, 100 mg/L, and 125 mg/L) of LC was studied, Potential to degrade LC was assessed by the growth of the bacteria in a mineral salts medium containing LC as the sole carbon source over 14 days. Five bacteria able to grow in MSM with LC as the sole source of carbon and on nutrient agar enriched with 100mg/L of LC were isolated. Their growth (turbidity and viable counts of the bacterial cells) increased from the third day till the sixth day, after which it declined till the 14th day. The Lambda Cyhalothrin-degrading bacterial isolates (LCDB) were tentatively identified as Bacillus species, Klebsiella species, Pseudomonas species, and Lysinibacillusspecies. These results indicated that these bacterial isolates are potentially able to degrade LC and can be useful for the remediation of SPs-contaminated agricultural soils.

Characterizing Atrazine Degradation by Molybdenum-reducing Pseudomonas sp.

The most feasible and economical technique for removal of toxic compounds in the polluted environment is bioremediation. This technique surpasses other physicochemical methods in recent time for being effective particularly at a lower concentration of the toxicant. In this study, seven (7) previously isolated molybdenum-reducing bacteria were screened for their potential to degrade atrazine herbicide as sole carbon source for growth. Bacterial colony count on mineral salt medium supplemented with atrazine was used for the screening, while the effects of incubation time, concentration, temperature, pH, inoculum size and heavy metals on atrazine biodegradation was used in characterizing the candidate isolate. Of the seven isolates, an isolate identified as Pseudomonas sp. that grew best with a count of 195 CFU/mL was chosen. The optimum conditions supporting atrazine degradation by Pseudomonas sp. were found to be temperature 35 °C, pH 7.0, incubation time 48 hours and 400 µL inoculum. The use of atrazine as carbon and electron donor source for molybdenum reduction, poorly support molybdenum blue (Mo-blue) production. At a concentration (2 ppm), heavy metals such as lead and copper did not significantly (p>0.05) affect atrazine biodegradation relative to control, iron and silver shows a relative stimulatory effect to the process, while mercury and zinc showed significant (p<0.05) inhibitory effect when compared to control. The ability of the isolate to degrade atrazine makes it an important instrument for bioremediation of this herbicide.

Degradation of DDT by a Novel Bacterium, Arthrobacter globiformis DC-1: Efficacy, Mechanism and Comparative Advantage

A novel bacterium, Arthrobacter globiformis DC-1, capable of degrading DDT as its sole carbon and energy source, was isolated from DDT-contaminated agricultural soil. The bacterium can degrade up to 76.3% of the DDT at a concentration of 10 mg/L in the mineral salt medium (MSM) within 1 day of incubation. The effects of various environmental conditions, such as the concentration of DDT, temperature, pH and additional carbon sources, on its growth and biodegrading capacity of DDT were investigated in the MSM. The A. globiformis DC-1 strain could efficiently grow and degrade DDT at a wide range of concentrations, with the maximum growth and degradation rate at 10 mg/LDDT, followed by inhibitory effects at higher concentrations (20 and 30 mg/LDDT). Mesophilic temperatures (25–30 °C) and a pH of 7–7.5 were the most suitable conditions for the growth and biodegradation. The presence of carbon sources significantly increased the growth of the DC-1 strain; however, degradation was inhibited in the present of glucose, sucrose and fructose, and peptone was determined to be the most appropriate carbon source for A. globiformis DC-1. The optimal DDT degradation (84.2%) was observed at 10 mg/LDDT, peptone as carbon source in pH 7.5 at 30 °C with 1 day of incubation. This strain could also degrade DDE, DDD and DDT simultaneously as the sole carbon and energy source, with degradation rates reaching 70.61%, 64.43% and 60.24% in 10 days, respectively. The biodegradation pathway by A. globiformis DC-1 revealed that DDT was converted to DDD and DDE via dechlorination and dehydrochlorination, respectively; subsequently, both DDD and DDE transformed to DDMU through further dechlorination, and finally, after ring opening, DDMU was mineralized to carbon dioxide. No intermediate metabolites accumulation was observed during the GC/MS analysis, demonstrating that the A. globiformis DC-1 strain can be used for the bioremediation of DDT residues in the environment.

Effect of salinity on the toxicity of diclofenac, ibuprofen and naproxen toward cyanobacterium Synechocystis salina

Aquatic species are continuously exposed to pharmaceuticals and changeable water conditions simultaneously, which can induce changes in the toxicity of pollutants. Cyanobacterium are an organism for which less ecotoxicological tests have been performed compared to green algae. In this study, we decided to check how selected non-steroidal anti-inflammatory drugs (NSAID) affect the grow of Synechocystis salina, picocyanobacterium isolated from the Baltic Sea, with salinity as potential modulator of toxicity. S. salina was exposed to diclofenac (DCF), ibuprofen (IBF) and naproxen (NPX) (nominal 100 mg L−1) in BG11 medium and sea salt supplemented BG11 medium (38 PSU) over 96 h in continuous light at 23 °C. No acute toxicity was found in both tested salinity levels. The comparable grow rate in exposed culture compared to control culture over 4 days indicate lack of stress for several generations which need to be overcome with substantial energy consumption. S. salina was found to be halotolerant and can be species for ecotoxicology test where salinity in an additional stressor. Furthermore, resistant of S. salina to target NSAIDs provide a competitive advantage over other phytoplankton species.

Pseudomonas aeruginosa based concurrent degradation of beta-cypermethrin and metabolite 3-phenoxybenzaldehyde, and its bioremediation efficacy in contaminated soils

Beta-cypermethrin is one of the widely used pyrethroid insecticides, and problems associated with the accumulation of its residues have aroused public attention. Thus, there is an urgent need to effectively remove the beta-cypermethrin that is present in the environment. Biodegradation is considered a cost-effective and environmentally friendly method for removing pesticide residues. However, the beta-cypermethrin-degrading microbes that are currently available are not optimal. In this study, Pseudomonas aeruginosa PAO1 was capable of efficiently degrading beta-cypermethrin and its major metabolite 3-phenoxybenzaldehyde in water/soil environments. Strain PAO1 could remove 91.4% of beta-cypermethrin (50 mg/L) in mineral salt medium within 120 h. At the same time, it also possesses a significant ability to metabolize 3-phenoxybenzaldehyde—a toxic intermediate of beta-cypermethrin. The Andrews equation showed that the maximum substrate utilization concentrations of beta-cypermethrin and 3-phenoxybenzaldehyde by PAO1 were 65.3558 and 49.6808 mg/L, respectively. Box–Behnken design-based response surface methodology revealed optimum conditions for the PAO1 strain-based degradation of beta-cypermethrin as temperature 30.6 °C, pH 7.7, and 0.2 g/L inoculum size. The results of soil remediation experiments showed that indigenous micro-organisms helped to promote the biodegradation of beta-cypermethrin in soil, and beta-cypermethrin half-life in non-sterilized soil was 6.84 days. The bacterium transformed beta-cypermethrin to produce five possible metabolites, including 3-phenoxybenzyl alcohol, methyl 2-(4-hydroxyphenoxy)benzoate, diisobutyl phthalate, 3,5-dimethoxyphenol, and 2,2-dimethyl-1-(4-phenoxyphenyl)propanone. Among them, methyl 2-(4-hydroxyphenoxy)benzoate and 3,5-dimethoxyphenol were first identified as the intermediate products during the beta-cypermethrin degradation. In addition, we propose a degradation pathway for beta-cypermethrin that is metabolized by strain PAO1. Beta-cypermethrin could be biotransformed firstly by hydrolysis of its carboxylester linkage, followed by cleavage of the diaryl bond and subsequent metabolism. Based on the above results, P. aeruginosa PAO1 could be a potent candidate for the beta-cypermethrin-contaminated environmental bioremediation.

Biodegradation of Petroleum Sludge by Methylobacterium sp. Strain ZASH.

A bacterium was isolated from sludge-contaminated soil in a petroleum refinery and tested for its ability to degrade aliphatic hydrocarbon compounds present in petroleum sludge. The isolate was grown on minimal salt media agar supplemented with 1% (w/v) petroleum sludge. The isolate was tentatively identified as Methylobacterium s p. s t rain ZASH based on the partial 16s rDNA molecular phylogeny. The bacterium grew optimally between the temperatures of 30°C and 35°C, pH 7 and 7.5, 0.5% and 1.5% (v/v) Tween 80 as the surfactant, and between 1% and 2% (w/v) peptone as the nitrogen source. The constants derived from the Haldane equation were μmax = 0.039 hr-1, Ks = 0.385% (w/v) total petroleum hydrocarbons (TPH) or 3,850 mg/L TPH, and Ki =1.12% (w/v) TPH or 11,200 mg/L. The maximum biodegradation rate exhibited by this strain was 19 mg/L/hr at an initial TPH concentration of 10,000 mg/L. Gas chromatography analysis revealed that after 15 days the strain was able to degrade all aliphatic n-alkanes investigated with different efficiencies. Shorter n-alkanes were generally degraded more rapidly than longer n-alkanes with 90% removal for C-12 compared to only 30% removal for C-36. The addition of sawdust did not improve bacterial degradation of petroleum hydrocarbons, but it assisted in the removal of remaining undegraded hydrocarbons through adsorption.

Organic Leachate and Biogas Utilization in Outdoor Microalgae Cultivation Under Alkaline Conditions at Pilot-Scale

The performance of an outdoor pilot-scale system consisting of a high rate algal pond interconnected to an absorption bubble column and seeded with a microalgal-bacterial consortium is presented. Biogas and organic leachate (from food waste anaerobic hydrolysis) were used as sources of CO2 and nutrients for the consortium, respectively. The removal efficiencies for CO2 and H2S from biogas were 80.0% and 99.9%, respectively, provoking a methane content in the utilized biogas of approximately 55 vol% for anaerobically-produced biogas and 90 vol% for a prepared gaseous mixture. The molecular oxygen produced by microalgae photosynthesis induced undesirable cumulation of O2 in utilized biogas up to 5%vol. The organic leachate was diluted in an alkaline mineral medium (15:1 v/v), and this rich-nutrient mixture was fed to the system at a hydraulic retention time of 138 d. The biomass productivity applying organic leachate and anaerobically-produced biogas was 2.6 g m−3 d−1, nine times lower than biomass productivity achieved when only mineral salt medium was fed, suggesting the existence of limited nutrient bioavailability. Microalgal-bacterial community shifts evaluated through molecular and morphological methods showed that a robust and stable photosynthetic population was maintained throughout the entire operation of the system, formed mainly by Picochlorum sp., Pseudanabaena sp., Spirulina sp., and Nitzschia sp., as well as heterotrophic bacteria and some microalgae predators. The valued by-products after waste utilization were clean and highly calorific biogas besides microalgae biomass, where the commercialization of the latter would determine the economic viability of biogas and leachate utilization.Graphical

Synthetic bacterial consortia enhanced the degradation of mixed priority phthalate ester pollutants

Dimethyl phthalate (DMP), diethyl phthalate (DEP), di-n-butyl phthalate (DBP), butyl benzyl phthalate (BBP), bis(2-ethylhexyl) phthalate (DEHP), and di-n-octyl phthalate (DOP) are hazardous chemicals listed as priority pollutants that disrupt endocrine systems. According to available reports, these six priority phthalate esters (PAEs) are considered the most polluting; however, no studies have been conducted on the efficient remediation of these PAEs. We therefore designed and constructed a synthetic bacterial consortium capable of the simultaneous and efficient degradation of six priority PAEs in minimal inorganic salt medium (MSM) and soil. The consortium comprised Glutamicibacter sp. ZJUTW, which demonstrates priority for degrading short-chain PAEs; Cupriavidus sp. LH1, which degrades phthalic acid (PA) and protocatechuic acid (PCA), intermediates of the PAE biodegradation process; and Gordonia sp. GZ-YC7, which efficiently degrades long-chain priority PAEs, including DEHP and DOP. In MSM containing the six mixed PAEs (250 mg/L each), the ZJUTW + YC + LH1 consortium completely degraded the four short-chain PAEs within 48 h, and DEHP (100%) and DOP (62.5%) within 72 h. In soil containing the six mixed PAEs (DMP, DEP, BBP, and DOP, 400 mg/kg each; DBP and DEHP, 500 mg/kg, each), the ZJUTW + YC + LH1 consortium completely degraded DMP, DEP, BBP, and DBP within 6 days, and 70.84% of DEHP and 66.24% of DOP within 2 weeks. The consortium efficiently degraded the six mixed PAEs in both MSM and soil. We thus believe that this synthetic microbial consortium is a strong candidate for the bioremediation of environments contaminated with mixed PAE pollutants.

Impact of thermal oxidation parameters on micro-hardness and hot corrosion of Ti-6Al-3Mo-2Nb-2Sn-2Zr-1.5Cr alloy

Protective oxide layers on Ti-6Al-3Mo-2Nb-2Sn-2Zr-1.5Cr (TC21) alloy with equiaxed microstructure considerably influence micro-hardness and hot corrosion resistance. The present work’s thermal oxidation of TC21 alloy was performed at 600, 700, and 800 °C for 5, 20, and 50 h durations. Hot corrosion methods in NaCl and NaCl + Na2SO4 salt media were applied to raw (unoxidized) and oxidized samples at 600 and 800 °C for 50 h. Hot corrosion was conducted at 600 °C for 5 cycles with 10-h steps. The best oxide layer thickness was observed at 800 °C, which increased with increased oxidation time and temperature. The surface hardness of the oxide layer at 800 °C was 900 ± 60 HV0.05 owing to the formation of TiO2 and Al2O3 phases. Raw material hardness was 342 ± 20 HV0.05, increasing threefold due to thermal oxidation. In the case of NaCl, weight loss dominated all samples except at 800 °C for 5 h. In the case of NaCl + Na2SO4, weight gain occurred at 600 and 800 °C for 5 h. Weight loss occurred for the raw samples and those processed at 800 °C for 20 and 50 h, where the oxide layer flaked off. Surface hardness increased upon hot corrosion testing because of the formation of brittle phases, such as TiO2 and Na4Ti5O12. Samples that oxidized at 800 °C for 5 h had the highest hardness and corrosion resistance.

Biodegradation characteristics of mixed phenol and p-cresol contaminants from a swine farm using bacteria immobilized in calcium alginate beads

Phenol and p-cresol, major odorous gases in swine farms, pose significant health risks and require efficient elimination. This study screened biofilm-derived bacteria from a local swine farm for effective phenol and p-cresol degradation. Isolated bacteria were exposed to 1000 ppm of phenol and p-cresol and cultivated in Mineral salts medium (MSM). Morphology, degradation characteristics, and 16S rRNA analysis were employed for identification. The isolate Proteobacteria and Actinobacteria, completely degraded phenol and p-cresol in water, up to 500 ppm, within 12 h. The mixtures of Proteobacteria and Actinobacteria eliminated 500 ppm of each compound within 28 h. Additionally, immobilized bacteria in calcium alginate beads exhibited reusable degradation activity for at least 5 cycles, with no decline in performance or bacterial loss. and no bacterial loss. This study highlights the potential of these bacterial strains and immobilization technique for effective VOC degradation in swine farm environments, improving odor control and environmental well-being.

Isolation of lignocellulolytic bacteria from oil palm mesocarp waste

In the present investigation, the bacterial strains were isolated from oil palm mesocarp waste dumped soil by serial dilution and pour plate method. The highest lignocellulolytic index was produced by bacterial isolate OPMW 6 (1.5 mm) followed by OPMW 5 (1.2 mm), OPMW 1 (0.83 mm), OPMW3 and OPMW 4 (0.71 mm). Changes in methylene blue color supplemented in nutrient broth from blue to light green or yellow were observed by three bacterial isolates (OPMW1, OPMW 3 and OPMW5), and rest of the bacterial isolatesrecorded less decolourization as the cultures were incubated between 24 and 48 hours respectively with highest percentage of dye decolourization produced by bacterial isolate i.e. OPMW5 (83.3%) and lowest rate ofdecolourization by bacterial isolate OPMW 6 (13.54%) as inoculated in nutrient broth supplemented with methylene blue dye. Utilization of gallic acid as supplemented in minimal salt media recorded positive reactionfor 4 bacterial isolates (OPMW 2, OPMW 5, OPMW 6 and OPMW 8) by the formation of dark colouration and addition ofa-naphthol in MSM inoculated broth culturesshowed formation of purple blue colour due to productionof laccase activity. Among the 4 best isolates having the highest indices, two isolates of bacteria (OPMW5 and OPMW6) had the best lignocellulolytic activity. Based on enzyme biosynthesis ability, the OPMW5 and OPMW6were selected as the best isolates as it can synthesie cellulase and ligninase enzymes. These enzymes are known to accelerate the degradation of oil palm mesocarp fibre substrate.

Size-Dependent Protein Adsorption on a Nanoparticle.

This study presents the mechanism of adsorption of a model protein within an electrical double layer (EDL) of a charged silica NP in an aqueous salt medium. In contrast to previous works, the charge regulation model analyzes the surface chemistry and electrostatic charge within the EDL by considering polarization, morphology, topography, and protonation/deprotonation. This model is coupled with the three protein adsorption models, such as Classical Langmuir (CLM), Extended Langmuir (ELM), and Two-State (TSM). By this means, surface curvature, conformational changes, and size- and pH-dependent characteristics of protein adsorption are allowed to be observed together in the present numerical model. For a parametric investigation, ionic concentration and pH of the solution, surface charge density, initial protein concentration, electrostatic charge of the protein, and the diameter of the NP are varied systematically. The validation studies with the experimental data agree well with the literature. The size-dependent protein adsorption is simulated and revealed with the current numerical model. Space charge density, chemistry, and morphology of NP's surface profoundly influence adsorption characteristics.

Production and characterization of a novel poly amino acid from a thermophilic bacterium, and preliminary testing of its coagulating potential for imminent wastewater treatment application

The increasing demand for biopolymers across diverse fields, such as food, medicine, cosmetics, and environmental applications, has prompted researchers to explore novel molecules with enhanced functionalities that meet these demands. In this study, a thermophilic strain of Bacillus licheniformis was employed to produce a unique polyamino acid. This thermophilic isolate exhibited rapid growth at 50 °C in a sucrose mineral salts medium, resulting in a biopolymer concentration of 7.4 g/L. Interestingly, the biopolymer produced at different temperatures exhibited varying glass-transition temperatures (ranging from 87.86 °C to 104.11 °C) and viscosities (7.5 cP to 16.3 cP), suggesting that the fermentation temperature significantly influenced the degree of polymerization. Furthermore, the biopolymer was characterized using various techniques, including Thin Layer Chromatography (TLC), Fourier Transform Infrared (FTIR) spectroscopy, Liquid Chromatography-Electrospray Ionization-Mass Spectroscopy (LC-ESI MS), Nuclear Magnetic Resonance (NMR), and Differential Scanning Calorimetry-Thermogravimetric Analysis (DSC-TGA). The results revealed that the obtained biopolymer was a poly amino acid, with poly-γ-glutamic acid as the major monomeric component in the polymer backbone with a few appendages of aspartic acid residues in its side chain. Finally, the biopolymer demonstrated significant coagulation potential for water treatment applications, as evidenced by coagulation studies conducted under varying pH conditions using kaolin-clay as a model precipitant.

Effects of Salinity Stress on Growth and Physiological Parameters and Related Gene Expression in Different Ecotypes of Sesuvium portulacastrum on Hainan Island.

We conducted a study to examine the growth and physiological changes in 12 different ecotypes of Sesuvium portulacastrum collected from Hainan Island in China. These ecotypes were subjected to different concentrations (0, 200, 400, and 600 mmol/L) of sodium chloride (NaCl) salt stress for 14 days. We also analyzed the expression of metabolic genes related to stress response. Under low salt stress, indicators such as plant height in region K (0 mmol/L: 45% and highest at 200 mmol/L: 80%), internode length (0 mmol/L: 0.38, 200 mmol/L: 0.87, 400 mmol/L: 0.25, and 600 mmol/L: 1.35), as well as leaf area, relative water content, fresh weight, and dry weight exhibited an overall increasing trend with the increase in salt concentration. However, as the salt concentration increased, these indicators showed a decreasing trend. Proline and malondialdehyde contents increased with higher salt concentrations. When the NaCl concentration was 400 mmol/L, MDA content in the leaves was highest in the regions E (196.23%), F (94.28%), J (170.10%), and K (136.08%) as compared to the control group, respectively. Most materials demonstrated a significant decrease in chlorophyll a, chlorophyll b, and total chlorophyll content compared to the control group. Furthermore, the ratio of chlorophyll a to chlorophyll b (Rab) varied among different materials. Using principal component analysis, we identified three ecotypes (L from Xinglong Village, Danzhou City; B from Shuigoupo Village, Lingshui County; and J from Haidongfang Park, Dongfang City) that represented high, medium, and low salt tolerance levels, respectively, based on the above growth and physiological indexes. To further investigate the expression changes of related genes at the transcriptional level, we employed qRT-PCR. The results showed that the relative expression of SpP5CS1, SpLOX1, and SpLOX1 genes increased with higher salt concentrations, which corresponded to the accumulation of proline and malondialdehyde content, respectively. However, the relative expression of SpCHL1a and SpCHL1b did not exhibit a consistent pattern. This study contributes to our understanding of the salt tolerance mechanism in the true halophyte S. portulacastrum, providing a solid theoretical foundation for further research in this field.