Optimization Of Physicochemical Parameters Research Articles

Present Scenario and Future Landscape of Payloads for ADCs: Focus on DNA-Interacting Agents

ADCs have emerged as a promising class of therapeutics, combining the targeting specificity of monoclonal antibodies with the cytotoxic potency of small-molecule drugs. Although the majority of approved ADCs are still based on microtubule binder payloads, the recent success of topoisomerase I inhibitors has revitalized interest in the identification of novel agents overcoming present limitations in the field including narrow therapeutic window and chemoresistance. The success of DNA binders as payload for ADCs has been very limited, up to now, due, among other factors, to high hydrophobicity and planar chemical structures resulting in most cases in ADCs with a strong tendency to aggregate, poor plasma stability, and limited therapeutic index. Some of these molecules, however, continue to be of interest due to their favorable properties in terms of cytotoxic potency even in chemoresistant settings, bystander and immunogenic cell death effects, and known combinability with approved drugs. We critically evaluated several clinically tested ADCs containing DNA binders, focusing on payload physicochemical properties, cytotoxic potency, and obtained clinical results. Our analysis suggests that further exploration of certain chemical classes, specifically anthracyclines and duocarmycins, based on the optimization of physicochemical parameters, reduction of cytotoxic potency, and careful design of targeting molecules is warranted. This approach will possibly result in a novel generation of payloads overcoming the limitations of clinically validated ADCs.

Production and characterization of bacteriocin from lactic acid bacteria isolated from fermented food products

Bacteriocin is a natal antimicrobial which can be exploited to evade the inevitability of adding chemical preservatives to food products. This study is aimed at the production and characterization of bacteriocin from Lactic acid bacteria (LAB) isolated from fermented food products. Sixteen (16) samples of various fermented food products (abacha, fufu, ogi and yoghurt) were screened for the presence of bacteriocin producing LAB using agar well diffusion method. The strain designated C6 was selected for further studies due to its broad inhibitory effect on the growth of all tested organisms (Enterococcus faecalis ATCC 33090, Pseudomonas aeruginosa MN 515053, Listeria innocua ATCC 2127, Staphylococcus aureus, Escherichia coli, Candida spp and Aspergillus terrus MN907795). Molecular characterization spotted C6 isolated from yoghurt as Lactobacillus fermentum (accession no. MN907811). Purification of the antimicrobial substance was achieved using High performance liquid chromatography (HPLC) with nisin as Standard which revealed it to be bacteriocin a proteinaceous antimicrobial that is stable to heat and organic solvents. Effect of substrate level on the growth of Lactobacillus fermentum and optimization of physicochemical parameters on bacteriocin production revealed optimum condition of 1.0 % glucose, 0.5 % sodium nitrate, pH of 6.0, incubation temperature of 35°C for 72h. This makes Lactobacillus fermentum and its bacteriocin a good antagonistic agent for exploitation in pharmaceutical and food processing industries as well as in the field of biotechnology.

Microbial production of docosahexaenoic acid (DHA): biosynthetic pathways, physical parameter optimization, and health benefits.

Omega-3 fatty acids, including docosahexaenoic acid (DHA), eicosapentaenoic acid (EPA), and α-linolenic acid (ALA), are essential polyunsaturated fatty acids with diverse health benefits. The limited conversion of dietary DHA necessitates its consumption as food supplements. Omega-3 fatty acids possess anti-arrhythmic and anti-inflammatory capabilities, contributing to cardiovascular health. Additionally, DHA consumption is linked to improved vision, brain, and memory development. Furthermore, omega-3 fatty acids offer protection against various health conditions, such as celiac disease, Alzheimer's, hypertension, thrombosis, heart diseases, depression, diabetes, and certain cancers. Fish oil from pelagic cold-water fish remains the primary source of omega-3 fatty acids, but the global population burden creates a demand-supply gap. Thus, researchers have explored alternative sources, including microbial systems, for omega-3 production. Microbial sources, particularly oleaginous actinomycetes, microalgae like Nannochloropsis and among microbial systems, Thraustochytrids stand out as they can store up to 50% of their dry weight in lipids. The microbial production of omega-3 fatty acids is a potential solution to meet the global demand, as these microorganisms can utilize various carbon sources, including organic waste. The biosynthesis of omega-3 fatty acids involves both aerobic and anaerobic pathways, with bacterial polyketide and PKS-like PUFA synthase as essential enzymatic complexes. Optimization of physicochemical parameters, such as carbon and nitrogen sources, pH, temperature, and salinity, plays a crucial role in maximizing DHA production in microbial systems. Overall, microbial sources hold significant promise in meeting the global demand for omega-3 fatty acids, offering an efficient and sustainable solution for enhancing human health.

Solar light assisted degradation of Rhodamine B dye by chemically synthesized silver nanoparticles

Utilization of dyes and dyestuff is increasing day by day, which affects environmental health and sustainability. Rhodamine B (RhB) is a synthetic xanthene class of dye that has a major application in cosmetic, painting, printing, and textile industries. The toxicity of RhB has been reported in animals, insects as well as humans in parts per billion (ppb) concentration. Exposure to this dye causes skin irritation, nervous system issues, and developmental changes. Therefore, the remediation of the dye is a crucial factor. The aim of this study was solar-assisted photocatalytic degradation of RhB. Synthesis of silver nanoparticles (AgNPs) was carried out with chemical reduction method, and characterization with the X-ray diffraction (XRD). The photocatalytic activity was checked with 1000 mL wastewater in which 10 ppm dye was added. Optimization of physicochemical parameters was performed by one-factor-at-a-time (OFAT) method. Maximum 99.32 % decolourization was observed at 2 g/L catalyst concentration, pH = 6, and 10 ppm dye concentration in 50 min irradiation time at 0.19 mg/L/min rate of decolourization. The initial degradation was confirmed based on chemical oxygen demand (COD) reduction; 89.25 % COD removal at a 0.17 mg/L/min rate was observed. The confirmation of degradation was carried out with UV-visible spectrophotometer and high-performance thin-layer chromatography (HPTLC) analysis. AgNPs were the efficient catalyst for the degradation of RhB. The toxicity study proved that, after degradation of RhB with AgNPs, the degraded products were less toxic than the original ones.

Process intensification for the enhancement of growth and chlorophyll molecules of isolated Chlorella thermophila: A systematic experimental and optimization approach

In our current work, we have optimized six physicochemical parameters (light intensity, light period, pH, inoculum size, culture period, and salt concentration) toward growth and chlorophyll synthesis using isolated fresh water microalgae Chlorella thermophila [contains ∼6% (w/w on dry biomass basis) chlorophyll]. Here, both experimental and computational [Taguchi orthogonal array (TOA), artificial neural network (ANN), and genetic algorithm (GA)] approaches were employed for the process intensification. Results revealed that the content of biomass and chlorophyll were enhanced by 118% and 95%, respectively, with productivity enhancement of 30% for biomass and 61% for chlorophyll from the optimization of physicochemical parameters. Further, optimum light intensity was found to be 128 µmol m−2 s−1 after conducting experiments in optimized chemical and physicochemical conditions, contributing to the enhancement of productivity of 46% for biomass and 106% for chlorophyll. Urea was found to be the most effective nitrogen source with an increase of 70% and 160% biomass and chlorophyll productivity, respectively. Moreover, sucrose as a carbon source contributed to an increase of 97% and 264% biomass and chlorophyll productivity.

Screening of Cellulolytic Bacteria from Various Ecosystems and Their Cellulases Production under Multi-Stress Conditions

Cellulose represents the most abundant component of plant biomass on earth; it is degraded by cellulases, specific enzymes produced by microorganisms. However, cellulases of bacterial origin attract more interest due to their natural diversity and ability to inhabit a variety of niches, allowing the selection of cellulolytic strains resistant to environmental stresses. The screening of the cellulolytic activity of 398 bacteria isolated from various ecosystems in Algeria (cave, ruins, chott, thermal station, and rhizosphere of arid and semi-arid regions) was performed by the appearance of a hydrolysis zone on carboxymethylcellulose (CMC) medium. The cellulase activity on CMC (1%) broth allowed to select 26 strains among which 12 had the best activity (0.3 U/mL to 2.2 U/mL). Optimization of physicochemical parameters (salinity: 0–1 M NaCl; pH: 3, 4, 7, 9, and 11; temperature: 30, 45, and 50 °C; PEG8000: 0 and 30%) involved in growth and cellulose production showed that the majority of strains were mesophilic, neutrophilic, or alkali- tolerant and tolerant to 30% of PEG8000. The cellulase activity and stability under different stress allowed to retain five strains, which the most efficient. Based on the 16S-rRNA sequencing results, they belonged to the genus Bacillus. The physicochemical properties of cellulases (crude extract) showed a CMCase active over a wide range of pH (4 to 11), optimal at 50 °C and 60 °C. The inhibiting salinity effect on the activity was not detected and was negligible on the enzymatic stability. The residual CMCase activity remained between 40 and 70% in a temperature range between 40 and 70 °C, was stable over a wide range of saline concentrations (0–2000 mM), and was weakly affected at 30% of PEG8000. The crude enzyme extract was able to hydrolyze both soluble and insoluble cellulosic substrates. The evaluation of the hydrolysis capacity of lignocellulosic waste revealed the ability of tested strains to degrade wheat bran, barley bran, and corncob. In addition, the enzyme showed significant multi-stress resistance on solid and liquid media. By these characteristics, these cellulolytic bacteria could be attractive to be used in various industrial and biotechnology applications.

Optimization of physicochemical parameters and characterization laccase enzyme produced by a novel strain of Fomes fomentarius through solid-state fermentation

Optimization of physicochemical parameters and characterization laccase enzyme produced by a novel strain of Fomes fomentarius through solid-state fermentation

Biohythane as a high potential fuel from anaerobic digestion of organic waste: A review

Recently, the bio-transformation of organic wastes to value-added products has gained huge interest due to problems related to waste disposal and fossil fuel depletion. Gaseous fuels such as biohydrogen and biomethane generation from biomass has been researched extensively and is well developed. Currently, biohythane, a gaseous mixure of biohydrogen and biomethane, with hydrogen composition of approximately 10–30% is gaining more attention due to its superior characteristics over other biofuels. The co-production of hydrogen and methane in two-stage process improves the total energy recovery up to 100% and 30% respectively compared to single-stage process. The optimal conditions for biohythane production are pH 5.5–6.5, 37 °C for 1–3 d during first stage, and pH 7–7.5, 37 °C for 10–15 d during second stage. Hythane with 10% and 20% (v v−1) hydrogen has achieved reduced NOx emission of 45% and 50% respectively in comparison with the methane fueled vehicles, whereas hythane with 30% (v v−1) hydrogen has achieved reduced CO2 emission of 69 g km−1. Although biohythane technology has high value as a vehicular fuel, its potential applications are yet to be explored. Enhanced biohythane quality and production rate can be obtained by selecting the most feasible substrates, controlling the microbial growth, using metabolically engineered strains and optimizing the bioreactor design. This review comprehensively discusses the mechanism of biohythane production; and its enhancement strategies such as pretreatment, co-digestion, optimization of physicochemical parameters and process integration to improvise the biohythane productivity. Finally, the techno-economic aspect for large scale biohythane production has also been addressed. In specific, this article discusses the latest achievements, their constraints and future prospects for lucrative biohythane generation.

Chryseobacterium aquifrigidense FANN1 Produced Detergent-Stable Metallokeratinase and Amino Acids Through the Abasement of Chicken Feathers

Microbial keratinases’ versatility in the beneficiation of keratinous waste biomass into high-value products prompts their application in diverse spheres hence, advancing green technology and the bioeconomy. Consequently, a feather-degrading Chryseobacterium aquifrigidense FANN1 (NCBI: MW169027) was used to produce keratinase, and its biochemical properties were determined. The optimization of physicochemical parameters and analysis of the free amino acid constituents of the feather hydrolysate were also carried out. FANN1 showed a maximum keratinase yield of 1,664.55 ± 42.43 U/mL after 72 h, at optimal process conditions that included initial medium pH, incubation temperature, inoculum size, and chicken feather concentration of 8, 30°C, 4% (v/v), and 15 (g/L), respectively. Analysis of degradation product showed 50.32% and 23.25% as the protein value and total free amino acids, respectively, with a relatively high abundance of arginine (2.25%) and serine (2.03%). FANN1 keratinase was optimally active at pH 8.0 and relatively moderate to high temperature (40–50°C). EDTA and 1,10-phenanthroline inhibited the keratinase activity, and that suggests a metallo-keratinase. The enzyme showed remarkable stability in the presence of chemical agents, with residual activity 141 ± 10.38%, 98 ± 0.43%, 111 ± 1.73%, 124 ± 0.87%, 104 ± 3.89%, 107 ± 7.79%, and 112 ± 0.86% against DTT, H2O2, DMSO, acetonitrile, triton X-100, tween-80, and SDS, respectively. The residual activity of FANN1 keratinase was enhanced by Sunlight (129%), Ariel (116%), MAQ (151%), and Surf (143%) compared to the control after 60 min preincubation. Likewise, the enzyme was remarkably stable in the presence Fe3+ (120 ± 5.06%), Ca2+ (100 ± 10.33%), Na+ (122 ± 2.95%), Al3+ (106 ± 10.33%); while Co2+ (68 ± 8.22%) and Fe2+ (51 ± 8.43%) elicited the most repressive effect on keratinase activity. The findings suggest that C. aquifrigidense FANN1 is a potential candidate for keratinous wastes bio-recycling, and the associated keratinase has a good prospect for application in detergent formulation.

Optimization of Growth Medium and Physicochemical Parameters for High-Yield Biomass Production and Active Metabolites from Aspergillus terreus

The selection of a nutrient medium and optimization of physicochemical parameters play a crucial role in the growth enhancement and production of bioactive secondary metabolites of fungi. The current study was to evaluate the influence of cultural conditions and physicochemical parameters affecting the growth and biomass production of Aspergillus terreus. Nutrient medium ((Potato dextrose broth, Czapek’s Dox broth, Sabouraud dextrose broth, Potato Carrot broth and malt extract broth) in conjunction with physicochemical parameters such as temperature, pH, nitrogen sources, carbon sources, and salinity were assessed for optimal biomass production. The growth rate of the fungus was measured by determining the mycelial dry weight, and enhancement of antioxidant activity through DPPH scavenging potency in the culture broth. The highest growth rate of the fungus was observed in potato dextrose broth (PDB) compared to the other nutrient media at a significant level (p< 0.05). The present study demonstrated that PDB supplemented with cellulose and urea as carbon and nitrogen sources with a pH of 5.5 and 4% salinity at 28°C are the suitable conditions for maximal growth and biomass production. However, the antioxidants activity was at its peak level in PDA enriched with sucrose and ammonium sulphate at pH 5.5, and 7% salinity at 28°C. Thus, culture conditions, including nutrient components and physicochemical parameters play an important role in the growth rate A. terreus, to exploit the maximum yield for various biomedical applications.

Bioethanol Production from Sugarcane Molasses an Industrial Waste Product

Due to recent increase in price hike of petroleum products, different efforts are being done throughout the world in search of an alternative source of fuel. For this reason, various agricultural countries are trying to produce their own fuel from plant based materials. Different types of biofuels like bioethanol, biodiesel, biohydrogen, biogas etc. are being investigated throughout the world. The type of the biofuel being produced depends upon the availability of the substrate. This review mainly focused on sugar industry waste called molasses, which is rich in fermentable sugars. The easiest form of the fuel that can be produced from sugar rich substrate is bioethanol, thus the review mainly focused on different methods of bioethanol production from molasses and the challenges related to this process. There are several factors that can affect the production of bioethanol that includes the type of substrate, the fermenting microorganisms, optimization of physicochemical parameters like pH, temperature, and the nutrient requirements of fermenting microbes for the conversion of sugar rich substrate into bioethanol. Moreover, the current scenario of the utilization of bioethanol as a fuel in various countries throughout the world was also discussed in this review.

Impact of redox-mediators in the degradation of olsalazine by marine-derived fungus, Aspergillus aculeatus strain bpo2: Response surface methodology, laccase stability and kinetics

The indiscriminate disposal of olsalazine in the environment poses a threat to human health and natural ecosystems because of its cytotoxic and genotoxic nature. In the present study, degradation efficiency of olsalazine by the marine-derived fungus, Aspergillus aculeatus (MT492456) was investigated. Optimization of physicochemical parameters (pH. Temperature, Dry weight) and redox mediators {(2,20-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt (ABTS), p-Coumaric acid and 1-hydroxybenzotriazole (HOBT)} was achieved with Response Surface Methodology (RSM)-Box-Behnken Design (BBD) resulting in 89.43% removal of olsalazine on 7th day. The second-order polynomial regression model was found to be statistically significant, adequate and fit with p < 0.0001, F value=41.87 and correlation coefficient (R2=0.9826). Biotransformation was enhanced in the redox mediator-laccase systems resulting in 99.5% degradation of olsalazine. The efficiency of ABTS in the removal of olsalazine was more pronounced than HOBT and p-Coumaric acid in the laccase-mediator system. This is attributed to the potent nature of the electron transfer mechanism deployed during oxidation of olsalazine. The pseudo-second-order kinetics revealed that the average half-life (t1/2) and removal rates (k1) increases with increasing concentrations of olsalazine. Michaelis-Menten kinetics affirmed the interaction between laccase and olsalazine under optimized conditions with maximum removal rate, Vmax=111.11 hr-1 and half-saturation constant, Km=1537 mg L-1. At the highest drug concentration (2 mM); 98%, 95% and 93% laccase was remarkably stabilized in the enzyme-drug degradation system by HOBT, ABTS and p-Coumaric acid respectively. This study further revealed that the deactivation of laccase by the redox mediators is adequately compensated with enhanced removal of olsalazine.

Optimization of Physicochemical Parameters during the Electrocoagulation Cadmium Elimination

The increased use of fertilizers from phosphates in agriculture generates water pollution by heavy metals contained in these phosphates at levels higher than the standards. In our study, we used a cadmium nitrate Cd(NO3)2 solution to simulate artificially polluted water, whose decontamination efficiency will be evaluated by an electrocoagulation/flotation process. During this work, we aimed to optimize the electrocoagulation process according to the following factors: initial pH of the solution, density of the electrolysis current, cell time, and nature of the supporting electrolyte and its concentration. The criteria adopted during the optimization of the process are relatively different from those used in similar studies. Indeed, we have tried to achieve maximum efficiency and also seeking to minimize costs and facilitate implementation. We achieved a 98% Cd removal efficiency from the solution at pH = 7, J = 6.25 A/m2, t = 10 min, and [K2SO4] = 0.01 M. In addition, during the characterization of the flocs obtained as a supernatant, we first highlighted the presence of Cd in this gelatinous body and then the relatively easy volatility of Cd as well as that of aluminum oxide (Al2O3).

Biomimetic Synthesis of Silver Nanoparticles from Aqueous Extract of Saraca indica and its Profound Antibacterial Activity

The present findings were focused on green synthesis of silver nanoparticles through an aqueous extract of Saraca indica. The stability of the nanoparticle was achieved through the optimization of physico-chemical parameters. The sharp UV-visible absorption maximum at 400 was observed for biological synthesized silver nanoparticles. The spectroscopic analysis was thus used to assess the formation of silver nanoparticles. The AFM analysis did analyze the morphology of the nanocomposite, which was further confirmed through TEM micrograph. The electron micrograph image discloses that silver nanoparticles were polydispersed and dominantly as spherical with size ranges from 40nm to 100nm. The average size distribution was 49nm. The chemical reductions of Ag+ ions were further confirmed through FTIR. The biogenic silver nanoparticle and their drug formulation showed profound antibacterial activity against pathogenic bacteria. The flavonoids rich binding of silver nanoparticle showed great medicinal potential and can be used for the treatment of several harmful infectious diseases. Hence, plant-based metal nanoparticles meet the demand for less toxic formulation during drug development and its delivery.

Preparation of a novel and highly stable Al-Fe loaded sepiolite catalyst for the CWPO of methyl orange: Optimization of physicochemical parameters, kinetics and thermodynamics studies

Al-Fe loaded sepiolite catalysts with different active metal ratio have been synthesized using a Turkish sepiolite sample from Eskişehir region. Liquid phase catalytic oxidation of methyl orange azo dye has been carried out over Al-Fe/sepiolite catalysts using hydrogen peroxide as oxidant. The catalytic studies are performed in a glass reactor under atmospheric pressure by semi-batch operation. The effects of several parameters such as catalyst amount, metal loading, calcination temperature, pH, H2O2 concentration, reaction temperature and time on the methyl orange elimination have been examined. The elimination rate of 90.68% was achieved when studied with the catalyst with 8% active metal ratio (SepAlFe8) at pH 3.7 and 25°C. Kinetics studies show the degradation of methyl orange over the SepAlFe8 catalyst could be expressed by the pseudo-first-order reaction kinetics (k1 = 0.0049 min-1 at 25°C). The activation energy (Ea) of the reaction over this catalyst is foundas 29.48 kJ mol-1. It was also found that the catalytic oxidation process is endothermic (ΔH = 26.99 kJ mol-1) and nonspontaneous (ΔG = 96.72 kJ mol-1 at 25°C). The catalyst is chemically stable and reusable with low release of iron.

Studies on Biodegradation of 4-Chlorophenol and 4-Nitrophenol by Isolated Pure Cultures

Metabolically versatile pure cultures were isolated from textile dye effluent and petrochemical industry which were able to utilize 150 mg/l of 4-Chlorophenol and 85 mg/l of 4-Nitrophenol as the sole carbon and energy source respectively. Phylogenetic analysis based on 16 S rRNA gene sequence reveals that the strains were found to be phylogenetically close to Bacillus cereus HWB1 and Pseudomonas taiwanensis ECAe22 respectively. Optimization of physicochemical parameters was performed with Change of one variable at a time (COVT) approach. Optimized physical parameters for degradation by Bacillus cereus HWB1 was found to be 30 0C, pH 7 and 150 rpm whereas for Pseudomonas taiwanensis ECAe22 it was found to be 30 0C, pH 8.5 and 150 rpm. Supplementation of an additional substrate such as yeast extract was found to increase the rate of 4-Chlorophenol and 4-Nitrophenol degradation owing to the increase in biomass production resulting in enhanced biodegradation. Biodegraded samples of these phenolic compounds showed negligible phytotoxicity as compared to the untreated samples thereby proving that employing these pure cultures can help in mitigating environmental contamination by phenolic compounds in the near future.Keywords: Biodegradation, 4-Chlorophenol,4-Nitrophenol, pure cultures,16S rRNA, phylogenetic analysisAbbreviation: 4-CP: 4-Chlorophenol; 4-NP: 4-Nitrophenol; AU: Absorbance Unit; MSM: MinimalSalt Media

Potential of Carica papaya Waste for the Production of Alginic Acid by Fermentation

The commercially available alginic acid is mainly extracted from sea weeds. Owing to the growing demand and variation in composition of alginate extracted from different species, there is rising interest in synthesis of alginate by bacteria. Therefore, present research was designed with the aim to check the potential of different papaya wastes like peels, seeds and decayed pulp for alginate production by Azotobacter vinelandii. Optimization of physico-chemical parameters was also done. Highest amount of the biopolymer was reported on fermentation of papaya peel at 72 hours of incubation period with inoculum size of 6% (v/v), at pH 7.0, 300C and agitation intensity of 200 rpm. Among different carbon and nitrogen sources tested, sucrose and peptone increased the yield of biopolymer (5.34 g/L). Alginate obtained was 98% pure in comparison to the standard. The present research is the first report on utilization of cheap papaya waste for alginate production and will be helpful to save the foreign exchange.

Optimization of physicochemical parameters in the biofabrication of gold nanoparticles using marine macroalgae Padina tetrastromatica and its catalytic efficacy in the degradation of organic dyes

Green synthesis of metallic nanoparticles by means of renewable bioresources has emerged as a new trend in current nanotechnology research with improved environmental safety. In the current study, monodispersed gold nanoparticles (AuNPs) with excellent stability were prepared in a completely green and cost effective manner using aqueous extract of marine macroalgae-Padina tetrastromatica. The influence of reaction conditions such as the quantity of seaweed extract, temperature, precursor metal ion concentration, reaction time and pH on the biosynthesis of nanoparticle was evaluated spectroscopically and also with the help of high resolution transmission electron microscopy (HR-TEM). These physicochemical parameters not only affected the rate of formation but also the size and morphology of resultant nanoparticles. Optimum conditions resulted in the generation of nearly spherical AuNPs having an average particle size of 11.4 nm. The high crystallinity of the biogenic AuNPs was confirmed from characteristic diffraction peaks in XRD profile, clear lattice fringes in the HR-TEM image and bright circular spots in the SAED pattern. The presence of metallic gold was evidenced from EDAX profile. FTIR study revealed the role of secondary metabolites in the bioreduction as well as stabilization of AuNPs. The study also highlights the spectroscopic investigation on the catalytic efficacy of the biosynthesized AuNPs in the reduction reactions of hazardous organic dyes, eosin yellow and Congo red using sodium borohydride, which have a pseudo-first order kinetics. Thus, the biosynthesized metal nanoparticles using renewable marine resources like seaweeds act as promising materials for the application in environmental protection.Graphical abstract

Decolourization and biodegradation of azo dye methyl red by Rhodococcus strain UCC 0016

ABSTRACTIn the present study, locally isolated Rhodococcus strains were attempted as biological tools for methyl red removal, a mutagenic azo dye posing threat to the environment if left untreated. Rhodococcus strain UCC 0016 demonstrated superior methyl red-decolourizing activity of 100% after 24 h at static condition in comparison to Rhodococcus strain UCC 0008 which recorded 65% decolourization after 72 h. Optimization of physicochemical parameters at 30°C, pH 7 and supplementing glucose as the carbon source resulted in improved methyl red-decolourizing activity at static condition and reduced the time taken to achieve complete decolourization by 80%. Higher concentration of methyl red (5 g/L) was able to be decolourized completely within 10 h by adopting the technology of immobilization. The encapsulated cells of Rhodococcus strain UCC 0016 demonstrated higher substrate affinity (Km = 0.6995 g/L) and an accelerated rate of disappearance of methyl red (Vmax = 0.3203 g/L/h) compared to the free cells. Furthermore, the gellan gum beads could be reused up to nine batches without substantial loss in the catalytic activity indicating the economic importance of this protocol. Analysis of methyl red degradation products revealed no germination inhibition on Triticum aestivum and Vigna radiata demonstrating complete toxicity removal of the parent dye after biological treatment. The occurrence of new and altered peaks (UV–Vis and FTIR) further supported the notion that the removal of methyl red by Rhodococcus strain UCC 0016 was indeed through biodegradation. Therefore, this strain has a huge potential as a candidate for efficient bioremediation of wastewater containing methyl red.

Two factor at a time approach by response surface methodology to aggrandize the Bacillus subtilis KLP2015 surfactin lipopeptide to use as antifungal agent

A Gram’s positive, rod shaped and endospores-forming ‘bacterial isolate KLP15′ was identified as Bacillus subtilis (Accession number KT459335) by the biochemical tests and 16S rRNA based sequencing. Lipopeptide(s) production from B. subtilis KLP2015 increased from 200.0 to 547.0 mg/l after the optimization of physico-chemical parameters like choice of nitrogen source, fermentation time, fermentation temperature and broth pH by ‘One Factor at a Time’ (OFAT) approach. Further, the yield of lipopeptide(s) increased to 985 mg/l from an earlier value of 547 mg/l when a “Two Factors at a Time (TFAT) approach using Response Surface Methodology (RSM) was attempted. The extracted crude lipopeptide fraction from the cell-free fermentation broth of B. subtilis KLP2015 was purified and characterized by High Performance Liquid Chromatography (HPLC), Thin Layer Chromatography (TLC), UV-Visible Spectrophotometry (UV-vis), Fourier Transform Infrared (FTIR) and MALDI-TOF studies. HPLC and TLC results confirmed the purity of the lipopeptide preparation and its Surfactin-type nature. The FTIR and MALDI-TOF spectra of the purified lipopeptide were found to be similar to that of an authentic Surfactin molecule. The purified lipopeptide showed potent 75.1% and 41.9% antifungal activity against Mucor sp. and Aspergillus niger, respectively on the basis of zone of inhibition of growth of these fungal strains. Moreover, the purified lipopeptide preparation of B. subtilis KLP2015 was most effective against the growth of Mucor sp. as reflected by the recorded MIC values of 6.25 µg/ml while MIC of lipopeptide for the A. niger was 12.5 µg/ml.