Comparison of pretreatment strategies of sugarcane baggase: experimental design for citric acid production

Improving dietary citric acid production by the wild-type Aspergillus niger ASP26 strain isolated from date by-product

This research investigates citric acid (CA) synthesis using the indigenous strain Aspergillus niger ASP26, which was isolated from date by-products. The study initially involved isolating fungi capable of CA production and identifying the most potent strain based on its characteristic enzymatic activity. A. niger ASP26 was acknowledged in a previous study for its remarkable ability to produce extracellular enzymes, such as cellulase and amylase, which enable it to degrade organic materials effectively. After the identification phase, these isolates were screened for CA production using a modified Czapek-Dox medium. The research identified significant factors affecting CA production in submerged fermentation, including pH, carbon source, inoculum size, and fermentation time. Optimal conditions were determined for A. niger ASP26, resulting in a maximum CA yield of 16.89 g/L. These conditions included a 2.5% spore suspension at 2 × 107 spores/mL, an initial glucose concentration of 125 g/L, and incubation at 30°C for 144 h. Notably, A. niger ASP26 demonstrated the ability to produce CA under stress conditions as well. Citric acid is essential for various biological processes, such as cellular respiration, and is naturally present in citrus fruits. It also serves as a preservative and flavor enhancer in processed foods and beverages. The ability of A. niger ASP26 to produce CA from agricultural residues positions it as a viable candidate for sustainable CA production, harnessing the value from organic waste materials.

Waste valorization as low-cost media engineering for auxin production from the newly isolated Streptomyces rubrogriseus AW22: Model development

Indole-3-acetic acid (IAA) represents a crucial phytohormone regulating specific tropic responses in plants and functions as a chemical signal between plant hosts and their symbionts. The Actinobacteria strain of AW22 with high IAA production ability was isolated in Algeria for the first time and was characterized as Streptomyces rubrogriseus through chemotaxonomic analysis and 16 S rDNA sequence alignment. The suitable medium for a maximum IAA yield was engineered in vitro and in silico using machine learning-assisted modeling. The primary low-cost feedstocks comprised various concentrations of spent coffee grounds (SCGs) and carob bean grounds (CBGs) extracts. Further, we combined the Box-Behnken design from response surface methodology (BBD-RSM) with artificial neural networks (ANNs) coupled with the genetic algorithm (GA). The critical process parameters screened via Plackett-Burman design (PBD) served as BBD and ANN-GA inputs, with IAA yield as the output variable. Analysis of the putative IAA using thin-layer chromatography (TLC) and (HPLC) revealed Rf values equal to 0.69 and a retention time of 3.711 min, equivalent to the authentic IAA. AW 22 achieved a maximum IAA yield of 188.290 ± 0.38 μg/mL using the process parameters generated by the ANN-GA model, consisting of L-Trp, 0.6%; SCG, 30%; T°, 25.8 °C; and pH 9, after eight days of incubation. An R² of 99.98%, adding to an MSE of 1.86 × 10^-5 at 129 epochs, postulated higher reliability of ANN-GA-approach in predicting responses, compared with BBD-RSM modeling exhibiting an R² of 76.28%. The validation experiments resulted in a 4.55-fold and 4.46-fold increase in IAA secretion, corresponding to ANN-GA and BBD-RSM models, respectively, confirming the validity of both models.

Advances in sustainable approaches utilizing orange peel waste to produce highly value-added bioproducts

Orange peel waste (OPW), a discarded part of orange fruit, is a rich source of essential constituents that can be transformed into highly value-added bioproducts. OPW is being generated in million tonnes globally and returns to the environment without complete benefit. Thus, a high volume of annually produced OPW in the industry requires effective valorization. In this regard, limited data is available that summarizes the broader spectrum for the sustainable fate of OPW to produce value-added bioproducts. The main objective of this treatise is to explore the sustainable production of bioproducts from OPW. Therefore, this review covers all the aspects of OPW, from its production to complete valorization. The review encompasses the extraction technologies employed for extracting different valuable bioactive compounds, such as: essential oil (EO), pectin, and carotenoids, from OPW. Furthermore, the suitability of bioconversion technologies (digestion/fermentation) in transforming OPW to other useful bioproducts, such as: biochemicals (lactic acid and succinic acid), biopolysaccharides (xanthan and curdlan gum), and bioenergy (biomethane and bioethanol) is discussed. Also, it includes the concept of OPW-based biorefineries and their development that shall play a definite role in future to cover demands for: food, chemicals, materials, fuels, power, and heat. Lastly, this review focuses on OPW-supplemented functional food products such as: beverages, yogurts, and extruded products. In conclusion, insights provided in this review maximize the potential of OPW for commercial purposes, leading to a safe, and waste-free environment.

Overview of lignocellulolytic enzyme systems with special reference to valorization of lignocellulosic biomass

Lignocellulosic biomass, one of the most valuable natural resources, is abundantly present on earth. Being a renewable feedstock, it harbors a great potential to be exploited as a raw material, to produce various value-added products. Lignocellulolytic microorganisms hold a unique position regarding the valorization of lignocellulosic biomass as they contain efficient enzyme systems capable of degrading this biomass. The ubiquitous nature of these microorganisms and their survival under extreme conditions have enabled their use as an effective producer of lignocellulolytic enzymes with improved biochemical features crucial to industrial bioconversion processes. These enzymes can prove to be an exquisite tool when it comes to the eco-friendly manufacturing of value-added products using waste material. This review focuses on highlighting the significance of lignocellulosic biomass, microbial sources of lignocellulolytic enzymes and their use in the formation of useful products.

Sequential process of solid-state cultivation with fungal consortium and ethanol fermentation by Saccharomyces cerevisiae from sugarcane bagasse

Solid-state cultivation (SSC) is the microbial growth on solid supports, producing a nutrient-rich solution by cell enzymes that may be further used as a generic microbial medium. "Second-generation" ethanol is obtained by fermentation from mainly the acid hydrolysates of lignocellulosic wastes, generating several microbial growth inhibitors. Thus, this research aimed at evaluating the feasibility of ethanol fermentation from sugarcane bagasse hydrolysate after SSC with vinasse as the impregnating solution by a consortium of A. niger and T. reesei as opposed to the conventional method of acid hydrolysis. Fermentation of the hydrolysate from SSC leading to the yield of 0.40 g g^-1, i.e., about 78% of maximum stoichiometric indicating that the nonconventional process allowed the use of two by-products from sugarcane processing in addition to ethanol production from glucose release.

Solid-State Cultivation of Aspergillus niger-Trichoderma reesei from Sugarcane Bagasse with Vinasse in Bench Packed-Bed Column Bioreactor

Solid-state cultivation (SSC) is microbial growth on solid supports under limited water conditions. Citric acid is a microbial aerobic metabolic product with several industrial applications, with production potential that can be obtained by SSF. Several wastes from agro-industries are used in SSF, such as sugarcane bagasse and vinasse. Cultures of mixed fungi or co-cultures are used in this SSF in order to complement the inoculum's xylanolytic enzymes for action on the lignocellulosic material (bagasse). Thus, this study aims to evaluate the effect of inoculum (Aspergillus niger and Trichoderma reesei consortium) in the production of citric acid from sugarcane bagasse impregnated with vinasse using bench packed-bed reactors (PBR). The results show the importance of T. reesei and A. niger in inoculum at a ratio of 50:50 and 25:75, suggesting the use of solid support due to the complementation of the hydrolytic enzymes. The highest concentration of citric acid, approximately 1000 mg L^-1, was obtained for 100 mm of bed height in 48 and 72 h, with maximum glucose yield in citric acid (2.2 mg _{citric acid} mg _glucose^-1). k_La indicates that maintaining solid moisture and liquid film thickness is important to keep the oxygen transfer in SSC.

Impacts of Chemical-Assisted Thermal Pretreatments on Methane Production from Fruit and Vegetable Harvesting Wastes: Process Optimization

The increasing population creates excess pressure on the plantation and production of fruits and vegetables across the world. Consumption demand during the whole year has made production compulsory in the covered production system (greenhouse). Production, harvesting, processing, transporting, and distribution chains of fruit and vegetables have resulted in a huge amount of wastes as an alternative source to produce biofuels. In this study, optimization of two pretreatment processes (NaOH and HCl assisted thermal) was investigated to enhance methane production from fruit and vegetable harvesting wastes (FVHW) that originate from greenhouses. NaOH concentration (0–6.5%), HCl concentration (0–5%), reaction temperature (60–100 °C), solid content (1–5%), time of reaction (1–5 h), and mixing speed (0–500 rpm) were chosen in a wide range of levels to optimize the process in a broad design boundary and to evaluate the positive and negative impacts of independent variables along with their ranges. Increasing NaOH and HCl concentrations resulted in higher COD solubilization but decreased the concentration of soluble sugars that can be converted directly into methane. Thus, the increasing concentrations of NaOH and HCl in the pretreatments have resulted in low methane production. The most important independent variables impacting COD and sugar solubilization were found to be chemical concentration (as NaOH and HCl), solid content and reaction temperature for the optimization of pretreatment processes. The high amount of methane productions in the range of 222–365 mL CH₄ gVS⁻¹ was obtained by the simple thermal application without using chemical agents as NaOH or HCl. Maximum enhancement of methane production was 47–68% compared to raw FVHW when 5% solid content, 1-hour reaction time and 60–100 °C reaction temperature were applied in pretreatments.

Evaluation of Oxalobacter formigenes DSM 4420 biodegradation activity for high oxalate media content: An in vitro model

Oxalate is a common component of many foods typically present as a salt of oxalic acid, which will be excreted in the urine. Hyperoxaluria is known to be a considerable risk factor for urolithiasis, and formation of oxalate kidney stone. Oxalate degradation by the probiotic anaerobic bacterium Oxalobacter formigenes DSM 4420 has high yield and efficiency both in the human colon helping to prevent hyperoxaluria and disorders such as the development of kidney stones and as a novel approach in reducing the high concentration of foodstuff oxalate content such as tea, coffee, and nuts. For determining the effective factors to enhance high concentration oxalate biodegradation activity of Oxalobacter formigenes DSM 4420 Plackett-Burman screening design was applied to evaluate the impact of 10 process variables. After determining the main factors by screening design, a response surface methodology was used to find suitable treatment combination for oxalate biodegradation by this probiotic. A second-order quadratic model estimated that the highest biodegradation of 60.2% was achieved in presence of 1.35 (g/L) inulin, 36.56 (g/L) glucose, 26 (mmol/L) ammonium oxalate, and pH 6. In other word, the optimum point showed that in the above condition the high concentration of ammonium oxalate content of 26 mmoL/L will reach to 9.95 mmoL/L. Reconfirmation experiment showed the validity of predicted optimum conditions. A surface model using the RSM and optimizing this model using the GA technique, resulted in a useful method of finding an optimal set of process parameters.

Optimization of fermentation conditions through response surface methodology for enhanced antibacterial metabolite production by Streptomyces sp. 1-14 from cassava rhizosphere

Streptomyces species 1-14 isolated from cassava rhizosphere soil were evaluated for their antibacterial efficacy against Fusarium oxysporum f.sp. cubense race 4 (FOC4). Of the 63 strains tested, thirteen exhibited potent antibacterial properties and were further screened against eight fungal pathogens. The strain that showed maximum inhibition against all of the test pathogens was identified by 16S rDNA sequencing as Streptomyces sp. 1-14, was selected for further studies. Through the propagation of Streptomyces sp. 1-14 in soil under simulated conditions, we found that FOC4 did not significantly influence the multiplication and survival of Streptomyces sp. 1-14, while indigenous microorganisms in the soil did significantly influence Streptomyces sp. 1-14 populations. To achieve maximum metabolite production, the growth of Streptomyces 1-14 was optimized through response surface methodology employing Plackett-Burman design, path of steepest ascent determinations and Box-Behnken design. The final optimized fermentation conditions (g/L) included: glucose, 38.877; CaCl2•2H2O, 0.161; temperature, 29.97°C; and inoculation amount, 8.93%. This optimization resulted in an antibacterial activity of 56.13% against FOC4, which was 12.33% higher than that before optimization (43.80%). The results obtained using response surface methodology to optimize the fermentation medium had a significant effect on the production of bioactive metabolites by Streptomyces sp. 1-14. Moreover, during fermentation and storage, pH, light, storage temperature, etc., must be closely monitored to reduce the formation of fermentation products with reduced antibacterial activity. This method is useful for further investigations of the production of anti-FOC4 substances, and could be used to develop bio-control agents to suppress or control banana fusarium wilt.

Simultaneous saccharification and aerobic fermentation of high titer cellulosic citric acid by filamentous fungus Aspergillus niger

Simultaneous saccharification and fermentation (SSF) is the most efficient operation in biorefining conversion, but aerobic SSF under high solids loading significantly faces the serious oxygen transfer limitation. This study took the first insight into an aerobic SSF by high oxygen demanding filamentous fungi in highly viscous lignocellulose hydrolysate. The results show that oxygen requirement in the aerobic SSF by Aspergillus niger was well satisfied for production of cellulosic citric acid. The record high citric acid titer of 136.3 g/L and the overall conversion yield of 74.9% of cellulose were obtained by the aerobic SSF. The advantage of SSF to the separate hydrolysis and fermentation (SHF) on citric acid fermentation was compared based on the rigorous Aspen Plus modeling. The techno-economic analysis indicates that the minimum citric acid selling price (MCSP) of $0.603 per kilogram by SSF was highly competitive with the commercial citric acid from starch feedstock.

Production of Aspergillus niger biomass on sugarcane distillery wastewater: physiological aspects and potential for biodiesel production

Background

Sugarcane distillery waste water (SDW) or vinasse is the residual liquid waste generated during sugarcane molasses fermentation and alcohol distillation. Worldwide, this effluent is responsible for serious environmental issues. In Reunion Island, between 100 and 200 thousand tons of SDW are produced each year by the three local distilleries. In this study, the potential of Aspergillus niger to reduce the pollution load of SDW and to produce interesting metabolites has been investigated.

Results

The fungal biomass yield was 35 g L⁻¹ corresponding to a yield of 0.47 g of biomass/g of vinasse without nutrient complementation. Analysis of sugar consumption indicated that mono-carbohydrates were initially released from residual polysaccharides and then gradually consumed until complete exhaustion. The high biomass yield likely arises from polysaccharides that are hydrolysed prior to be assimilated as monosaccharides and from organic acids and other complex compounds that provided additional C-sources for growth. Comparison of the size exclusion chromatography profiles of raw and pre-treated vinasse confirmed the conversion of humic- and/or phenolic-like molecules into protein-like metabolites. As a consequence, chemical oxygen demand of vinasse decreased by 53%. Interestingly, analysis of intracellular lipids of the biomass revealed high content in oleic acid and physical properties relevant for biodiesel application.

Conclusions

The soft-rot fungus A. niger demonstrated a great ability to grow on vinasse and to degrade this complex and hostile medium. The high biomass production is accompanied by a utilization of carbon sources like residual carbohydrates, organic acids and more complex molecules such as melanoidins. We also showed that intracellular lipids from fungal biomass can efficiently be exploited into biodiesel.

Electronic supplementary material

The online version of this article (10.1186/s40694-018-0045-6) contains supplementary material, which is available to authorized users.

Effect of probiotics on patulin removal from synbiotic apple juice

BACKGROUND

Studies have reported the occurrence of the mycotoxin patulin in apple products. The aim of this study was to produce synbiotic apple juice and investigate the detoxification of patulin by Lactobacillus acidophilus and Lactobacillus plantarum as probiotic strains. The impact of seven process variables on efficiency of toxin removal was investigated using Plackett-Burman design and presence of the surface-layer proteins as binding site of probiotics to patulin was confirmed during 6 weeks of cold storage.

RESULTS

Results showed that the removal of patulin by probiotic bacteria from apple juice depends significantly (P < 0.05) on the fructooligosaccharide content (as a prebiotic), concentration of patulin and the addition of ascorbic acid. Sodium dodecyl sulfate polyacrylamide gel electrophoresis of cell surface proteins of probiotic strains revealed that surface layer proteins have an important role in patulin removal from apple juice. In the best conditions, 91.23% of initial patulin concentration was removed from juice during 6 weeks refrigerated storage. No significant difference was observed in organoleptic properties of the synbiotic apple juice and raw sample.

CONCLUSION

In the best condition reported in this study, contaminated synbiotic apple juice by patulin will be safe for consumers after the first day of probiotic inoculation. © 2016 Society of Chemical Industry.

Fermentative production of high titer citric acid from corn stover feedstock after dry dilute acid pretreatment and biodetoxification

The aim of this work is to study the citric acid fermentation by a robust strain Aspergillus niger SIIM M288 using corn stover feedstock after dry dilute sulfuric acid pretreatment and biodetoxification. Citric acid at 100.04g/L with the yield of 94.11% was obtained, which are comparable to the starch or sucrose based citric acid fermentation. No free wastewater was generated in the overall process from the pretreatment to citric acid fermentation. Abundant divalent metal ions as well as high titer of potassium, phosphate, and nitrogen were found in corn stover hydrolysate. Further addition of extra nutrients showed no impact on increasing citric acid formation except minimum nitrogen source was required. Various fermentation parameters were tested and only minimum regulation was required during the fermentation. This study provided a biorefining process for citric acid fermentation from lignocellulose feedstock with the maximum citric acid titer and yield.

Preparation and characterization of amine-functionalized sugarcane bagasse for CO2 capture

A low-cost solid amine adsorbent for CO2 capture was prepared by using sugarcane bagasse (SB), a dominant agro-industrial residue in the sugar and alcohol industry as raw materials. In this preparation process, acrylamide was grafted on SB, and the grafted fiber was then aminated with different type of amine reagents to introduce primary and secondary amine groups onto the surface of SB fibers. The graft and amination conditions were optimized. The prepared solid amine adsorbent showed remarkable CO2 adsorption capacity and the adsorption capacity of the solid amine adsorbent could reach 5.01 mmol CO2/g at room temperature. The comparison of adsorption capacities of amine fibers aminated with various amination agents demonstrated that fibers aminated with triethylenetetramine would obtain higher adsorption capacities and higher amine efficiency. These adsorbents also showed good regeneration performance, the regenerated adsorbent could maintain almost the same adsorption capacity for CO2 after 10 recycles.

Effectiveness of biostimulation through nutrient content on the bioremediation of phenanthrene contaminated soil

Bioremediation has shown its applicability for removal of polycyclic aromatic hydrocarbons (PAHs) from soil and sediments. In the present study, the effect of biostimulation on phenanthrene removal from contaminated soil via adding macro and/or micronutrients and trace elements was investigated. For these purposes three macro nutrients (as N, P and K), eight micronutrients (as Mg, S, Fe, Cl, Zn, Mn, Cu and Na) and four trace elements (as B, Mo, Co and Ni) in 11 mineral salts (MS) as variables were used. Placket-Burman statistical design was used to evaluate significance of variables (MS) in two levels of high and low. A consortium of adapted microorganisms with PAHs was used for inoculation to the soil slurry which was spiked with phenanthrene in concentration of 500 mg/kg soil. The optimal reduction resulted when a high level of macro nutrient in the range of 67-87% and low level of micro nutrient in the range of 12-32% were used with the nitrogen as the dominant macronutrient. The Pareto chart showed that NH4NO3 was the most effective variable in this experiment. The effect of elements on phenanthrene biodegradation showed following sequence as N > K > P > Cl > Na > Mg. Effectiveness of the other elements in all runs was less than 1%. The type and concentration of nutrient can play an important role in biodegradation of phenanthrene. Biostimulation with suitable combination of nutrient can enhance bioremediation of PAHs contaminated soils.

The encapsulation of flavourzyme in nanoliposome by heating method

The main objective of this study was to use heating method (HM) to prepare liposome without employing any chemical solvent or detergent. Plackett-Burman design (PBD) was applied for the screening of significant process variables including the lecithin proportion, the cholesterol/lecithin ratio, the pH of solution for liposome preparation, the enzyme/lecithin ratio, the stirring time, the process temperature, the speed of stirrer, the ratio of stirrer to the tank diameter, the application of homogenization, the method of adding enzyme and centrifugation conditions on the encapsulation efficiency (EE %) of liposome and the activity of liposomal Flavourzyme (LAPU(-1)) (P < 0.05). Then, the response surface methodology based on the central composite design (CCD) was applied for the evaluation of the impacts of the significant mentioned variables on the EE (%) and the activity of the liposomal Flavourzyme. The results indicated that the lecithin proportion and the stirring time were the major influential variables for both responses. The most suitable formulation of the Flavourzyme-loaded liposome is 4.5 % lecithin, 45 °C temperature, 5 % Flavourzyme/lecithin ratio, 30 min stirring time and medium pH of 6. Under suitable operating conditions, the EE of liposome and the activity of the liposomal Flavourzyme were achieved as 26.5 % and 9.96 LAPU ml(-1), respectively. AFM technique and size distribution clearly showed the diameter of 189 nm for the spherical shape of the Flavourzyme- loaded nanoliposome.

Comparative secretome analysis of Trichoderma asperellum S4F8 and Trichoderma reesei Rut C30 during solid-state fermentation on sugarcane bagasse

BACKGROUND

The lignocellulosic enzymes of Trichoderma species have received particular attention with regard to biomass conversion to biofuels, but the production cost of these enzymes remains a significant hurdle for their commercial application. In this study, we quantitatively compared the lignocellulolytic enzyme profile of a newly isolated Trichoderma asperellum S4F8 strain with that of Trichoderma reesei Rut C30, cultured on sugarcane bagasse (SCB) using solid-state fermentation (SSF).

RESULTS

Comparison of the lignocellulolytic enzyme profiles of S4F8 and Rut C30 showed that S4F8 had significantly higher hemicellulase and β-glucosidase enzyme activities. Liquid chromatography tandem mass spectrometry analysis of the two fungal secretomes enabled the detection of 815 proteins in total, with 418 and 397 proteins being specific for S4F8 and Rut C30, respectively, and 174 proteins being common to both strains. In-depth analysis of the associated biological functions and the representation of glycoside hydrolase family members within the two secretomes indicated that the S4F8 secretome contained a higher diversity of main and side chain hemicellulases and β-glucosidases, and an increased abundance of some of these proteins compared with the Rut C30 secretome.

CONCLUSIONS

In SCB SSF, T. asperellum S4F8 produced a more complex lignocellulolytic cocktail, with enhanced hemicellulose and cellobiose hydrolysis potential, compared with T. reesei Rut C30. This bodes well for the development of a more cost-effective and efficient lignocellulolytic enzyme cocktail from T. asperellum for lignocellulosic feedstock hydrolysis.

Improvement of recombinant endoglucanase produced in Pichia pastoris KM71 through the use of synthetic medium for inoculum and pH control of proteolysis

The long lag time in basal salts medium (BSM) and an occurrence of proteolysis are major problems for recombinant protein production in Pichia pastoris KM71. In this study, optimal conditions were explored for fed-batch cultivation of recombinant fungal endoglucanase in P. pastoris KM71. It was found that lag and process times were much reduced when the synthetic FM22 medium was used for the inoculum compared with enriched buffered glycerol complex (BMGY) medium. The highest endoglucanase activity was obtained at 30°C which was more than 10 fold higher than that produced from shake flask. At 30°C, the specific endoglucanase activity was dependent on culture pH and a higher specific activity was observed at pH 5.0 than at pH 6.0. The higher activity was likely due to lower rate of proteolysis, since a truncated protein species was apparent at pH 6.0, but not pH 5.0. Thus, production of endoglucanase at 30°C and pH 5.0 is the optimal condition suitable for economical production in large scale. The combination of using synthetic FM22 medium for inoculum and proteolysis control by growth at lower pH could be applied for production of other recombinant proteins in P. pastoris.

Low cost CaCl₂ pretreatment of sugarcane bagasse for enhancement of textile dyes adsorption and subsequent biodegradation of adsorbed dyes under solid state fermentation

Pretreatments to sugarcane bagasse (SCB) such as CaCl2, alkali, ammonia, steam and milling showed 91%, 46%, 47%, 42% and 56% adsorption of Solvent Red 5B (SR5B); 92%, 57%, 58%, 56% and 68% adsorption of simulated dyes mixture (SDM), and 86%, 45%, 49%, 44% and 56% adsorption of a real textile effluent (RTE), respectively. However, the untreated SCB showed 32%, 38% and 30% adsorption of SR5B, SDM and RTE, respectively. Adsorption of SR5B on CaCl2 pretreated SCB follows pseudo-second order kinetics. SEM and FTIR analysis reveals the delignification of CaCl2 pretreated SCB. SR5B, SDM and RTE adsorbed on CaCl2, alkali, ammonia, steam and milling pretreated SCB were decolorized under solid state fermentation using isolated Providencia staurti strain EbtSPG. Tray bioreactor study showed 86% American Dye Manufacturers Institute (ADMI) removal of RTE in 72h. Biodegradation of adsorbed SR5B was confirmed using FTIR, HPLC and HPTLC.