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Abstract: Conidiation and lytic enzyme production by Trichoderma viride at different solids concentration of pre-treated municipal wastewater sludge was examined in a 15-L fermenter. The maximum conidia concentration (5.94×107 CFUmL−1 at 96h) was obtained at 30gL−1 suspended solids. The maximum lytic enzyme activities were achieved around 12–30h of fermentation. Bioassay against a fungal phytopathogen, Fusarium sp. showed maximum activity in the sample drawn around 96h of fermentation at 30gL−1 suspended solids concentration. Entomotoxicity against spruce budworm larvae showed maximum value ≈17290SBUμL−1 at 30gL−1 suspended solids concentration at the end of fermentation (96h). Plant bioassay showed dual action of T. viride, i.e., disease prevention and growth promotion. The rheological analyses of fermentation sludges showed the pseudoplastic behaviour. In order to maintain required dissolved oxygen concentration ≥30%, the agitation and aeration requirements significantly increased at 35gL−1 compared to 30 and 25gL−1. The oxygen uptake rate and volumetric oxygen mass transfer coefficient, k L a at 35gL−1 did not increase in comparison to 30gL−1 due to rheological complexity of the broth during fermentation. Thus, the successful fermentation operation of the biocontrol fungus T. viride is a rational indication of its potential for mass-scale production for agriculture and forest sector as a biocontrol agent. [Copyright &y& Elsevier]

Pulp and paper solid waste (PPSW) originating from paper industry, was experimented for the production of fumaric acid (FA) through submerged and solid state fermentation by utilizing the filamentous fungus Rhizopus oryzae 1526 . Physicochemical characterization, pH and moisture content analysis of PPSW was carried out. Pre-treatment of PPSW by size reduction resulted in particles of different size ranges (1.7 mm < x ≤ 3.35 mm, 850 μm < x ≤ 1.7 mm, 300 μm < x ≤ 850 μm, 75 μm < x ≤ 300 μm and 33 μm < x ≤ 75 μm). In submerged fermentation with all particle size ranges, a maximum of 23.47 ± 0.70 g/L of FA was obtained with 33 μm < x ≤ 75 μm under the fermentation conditions of 30 °C, 200 rpm, 5% pre-cultured inoculum ( v/v ) and at 48 h. Viscosity measurement and analysis of by-product of the fermented broths were performed. Microwave-phosphoric acid mediated hydrolysis of 33 μm < x ≤ 75 μm particle size produced hydrolysate with maximum glucose (11.2 ± 0.8 g/L) and xylose (20.22 ± 0.85 g/L) contents. Submerged fermentation with this hydrolysate confirmed the utilization of xylose for both FA production and fungal growth. Solid state fermentation with 75 μm < x ≤ 300 μm particle size resulted in highest FA production (41.45 g/kg dry weight) after 21 days. Scanning electron microscopy revealed the morphological features of the fungus grown on the particles. The results of the present study confirmed the utilization of PPSW as a source of carbon and trace elements by the fungus R. oryzae 1526 and also the bioconversion into FA during fermentation. FA being a high value platform chemical, its bioproduction from the low cost PPSW, is a value addition approach. [ABSTRACT FROM AUTHOR]

The present research account deals with the bioproduction of fumaric acid (FA) from apple pomace ultrafiltration sludge (APUS) and apple pomace (AP) through fermentation. The filamentous fungus Rhizopus oryzae 1526 was used as a biocatalyst and its morphological impact on FA production was analysed in detail. For submerged fermentation, 40 g L −1 of total solids concentration of APUS, pH 6.0, 30 °C, 200 rpm flask shaking speed and 72 h of incubation were found to be optimum for FA production (25.2 ± 1.0 g L −1 , 0.350 g (L −1 h −1 )). Broth viscosity (cP), residual reducing sugar (g L −1 ) and ethanol (g L −1 ) produced as by-product, were also analysed. Plastic trays were used for solid state fermentation and at optimized level of moisture and incubation period, 52 ± 2.67 g FA per kg dry weight of AP was obtained. Changes in the total phenolic content (mg g −1 dry weight of AP) were monitored at regular intervals. Utilization of APUS and AP for the directed synthesis of the high-value platform chemical FA by the fungal strain R. oryzae 1526 was an excellent display of fungal physiological and morphological control over a fermentative product. [ABSTRACT FROM AUTHOR]

Summary Submerged citric acid (CA) bioproduction was carried out by Aspergillus niger NRRL-567 using various industrial wastes, such as brewery spent liquid (BSL), lactoserum and starch industry water sludge. CA bioproduction was carried out by varying the temperature (25-35 °C), pH (3-5), addition of inducers, incubation time and supplementation with different proportions of apple pomace ultrafiltration sludge (APS). The results indicated that under the best conditions with 3% (v/v) methanol, the optimal concentration of 11.34 g L−1 CA was recorded using BSL at pH 3.5 and temperature 30 °C after 120-h incubation period. Supplementation of methanol resulted in an increase of 56% CA production. Meanwhile, under similar conditions, higher concentration of 18.34 g L−1 CA was reported with the supplementation of BSL with 40% (v/v) APS having suspended solids concentration of 30 g L−1. The present study demonstrated the potential of BSL supplemented with APS as an alternative cheap substrate for CA fermentation. [ABSTRACT FROM AUTHOR]

Abstract: Ever-growing demand for citric acid (CA) and urgent need for alternative sources has served as a driving force for workers to search for novel and economical substrates. Submerged fermentation was conducted using apple (Malus domestica) pomace ultrafiltration sludge as an inexpensive substrate for CA bioproduction, using Aspergillus niger NRRL567. The crucial parameters, such as total suspended solids and inducer concentration, were optimised by response surface methodology for higher CA production. The optimal CA concentrations of 44.9g/100g and 37.9g/100g dry substrate were obtained with 25g/l of initial total solids and 3% (v/v) methanol and 25g/l of total solids and 3% (v/v) ethanol concentration, respectively, after the 144h of fermentation. Results indicated that total solids concentration, and methanol as an inducer, were effective with respect to higher CA yield and also indicated the possibility of using apple pomace sludge as a potential substrate for economical production of CA. [Copyright &y& Elsevier]

Abstract: In view of ever growing demand of citric acid, there is an urgent need to look for inexpensive and novel substrates for feasible production of citric acid. In this context, the present study was carried out to evaluate the potential of different agro-industrial wastes for hyper production of citric acid through solid-state and submerged fermentation by Aspergillus niger NRRL 567 and NRRL 2001. It was found that among all the solid substrates utilized, apple pomace with 66.0±1.9g/kg of dry substrate proved to be an excellent substrate for citric acid production by A. niger NRRL 567 at 72h of incubation. A. niger NRRL 2001 resulted in slightly lower citric acid concentration of 61.0±1.9g/kg of dry substrate at the same incubation time. APS-1 (apple pomace ultrafiltration sludge-1) gave highest citric acid production rate of 9.0±0.3g/l and 8.9±0.3g/l of substrate by A. niger NRRL 567 and NRRL 2001 by submerged fermentation, respectively. Further study with apple pomace and apple pomace ultrafiltration sludge-1 by A. niger NRRL 567 was carried out. Addition of 3% (v/w) ethanol and 4% (v/w) methanol to apple pomace gave significantly higher citric acid values of 127.9±4.3g/kg and 115.8±3.8g/kg of dry substrate by A. niger NRRL 567 by solid-state fermentation. Higher citric acid values of 18.2±0.4g/l and 13.9±0.4g/l of apple pomace ultrafiltration sludge-1 were attained after addition of 3% (v/v) ethanol and 4% (v/v) methanol, respectively by A. niger NRRL 567. Apple pomace solid waste and apple pomace ultrafiltration sludge-1 thus proved to be an excellent source for citric acid production, of the different substrates chosen. [Copyright &y& Elsevier]

The paper discusses the potential of different waste biomaterials for biosorption. Waste biomaterials after citric acid fermentation and chitosan extraction using Aspergillus niger were evaluated for biosorption of toxic metals (Cu, Cr and As) from leachates of chromated copper arsenate woods. The different waste BMs, such as fungal biomass (living and dead), alkali insoluble material and acid and alkali insoluble material were used in this study. The effect of different parameters, such as biosorbent concentration, metal concentration and contact time were investigated. The fitness of biosorption data for Freundlich and Langmuir adsorption models was investigated through batch adsorption technique. Among the adsorption isotherm tested, Langmuir isotherm gave the best fit with correlation coefficients (R 2 ) value ranging from 0.89 to 0.97; 0.96–0.99 and 0.76–0.95 for As, Cr and Cu, respectively using solid state fermented biomass. Similarly, the significant removal of metals (>60% in leachate 2) from waste CCA wood leachate was achieved with the different BMs. Therefore, this study demonstrates the potential of CA fermentation derived waste BMs for biosorption of toxic metals from waste waters. [ABSTRACT FROM AUTHOR]

Butanol produced from renewable feedstock is defined as an emerging biofuel and biochemical. Research efforts made during the last three decades on biochemical production of butanol via conventional ABE (acetone-ethanol-butanol) fermentation has tried to bring biobutanol close to competition with petrobutanol. However, each new effort of development has been often countered by new challenges, confining biobutanol production mostly to the laboratory scale. This review provides a systematic, comparative analysis of different steps in biochemical production of butanol and identifies the counteractive aspects and challenges to overcome. A special emphasis is given on process inhibitors, applied detoxification techniques, chemical supplements and research & development in industry in order to enhance and update ABE fermentation and make it cost effective. Biobutanol future lies in utilization of inexpensive cellulose enriched lignocellulosic hydrolysates and hyper-butanol producing bacteria, combined with specific detoxification techniques and followed by efficient continuous fermentation technologies together with in situ product recovery. [ABSTRACT FROM AUTHOR]

Biobutanol has conventionally been generated by fermentation of carbohydrates derived from biomass (starch or sugar-based feedstock, such as corn) using Clostridia strains (mainly C. beijerinckii and C. acetobutylicum) under anaerobic conditions in batch mode. Under these premises, it has been tough for the acetone-butanol-ethanol fermentation to compete with petro-butanol production from an energy efficiency and material consumption standpoint. Challenges for butanol production from biomass comprised high cost of feedstock, scarcity of hyper-butanol producing bacteria and low butanol yield, volumetric productivity and titre, leading to high water usage and separation-purification costs. This article is an up-to-date review on several under explored sections, such as optimization of fermenter feed, microbial culture responsible for solvent production (co-culture techniques and electro-biochemical process), latest recovery techniques and the studies integrating in situ continuous fermentation processes. Biobutanol refinery way forward should build upon the use of low-cost lignocellulosic matter and zero cost organic wastes and by-products from food, agriculture, forestry, fermentation and paper industries as feedstock; optimized fermentation of such diversified feed with appropriate hyper-butanol producing strains in biofilm reactors and integration of fermentation step with hybrid high butanol-selective recovery techniques. Copyright © 2015 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Co-substrate utilization of various wastes with complementary characteristics can provide a complete medium for higher hydrogen production. This study evaluated potential of apple pomace hydrolysate (APH) co-fermented with crude glycerol (CG) for increased H 2 production and decreased by-products formation. The central composite design (CCD) along with response surface methodology (RSM) was used as tool for optimization and 15 g/L of CG, 5 g/L of APH and 15% (v/v) inoculum were found to be optimum to produce as high as 26.07 ± 1.57 mmol H 2 /L of medium. The p -value of 0.0017 indicated that APH at lower concentration had a significant effect on H 2 production. By using CG as sole carbon source, reductive pathway of glycerol metabolism was favored with 19.46 mmol H 2 /L. However, with APH, oxidative pathway was favored with higher H 2 production (26.07 ± 1.57 mmol/L) and decrease in reduced by-products (1,3-propanediol and ethanol) formation. APH inclusion enhanced H 2 production, and decreased substrate inhibition. [ABSTRACT FROM AUTHOR]

A new, simple, rapid and selective spectrophotometric method has been developed for detection and estimation of butanol in fermentation broth. The red colored compound, produced during reduction of diquat-dibromide-monohydrate with 2-mercaptoethanol in aqueous solution at high pH (>13), becomes purple on phase transfer to butanol and gives distinct absorption at λ 520 nm . Estimation of butanol in the fermentation broth has been performed by salting out extraction (SOE) using saturated K 3 PO 4 solution at high pH (>13) followed by absorbance measurement using diquat reagent. Compatibility and optimization of diquat reagent concentration for detection and estimation of butanol concentration in the fermentation broth range was verified by central composite design. A standard curve was constructed to estimate butanol in acetone–ethanol–butanol (ABE) mixture under optimized conditions. The spectrophotometric results for butanol estimation, was found to have 87.5% concordance with the data from gas chromatographic analysis. [ABSTRACT FROM AUTHOR]

CG (Crude glycerol) is one of the major wastes of biodiesel production process. It can be used as a substrate for lipid production by algae and the produced lipid can be recycled as a feedstock for biodiesel production. In order to avoid substrate inhibition, lipid production media are prepared by diluting the CG with distilled water. However, CG contains only a small amount of Mg (57.41 ± 18 ppm) and its concentration is further decreased to around 0.57 ppm during the dilution process. Apart from having a number of roles in algal physiology, Mg is the central atom of chlorophyll. Therefore, MgSO 4 was evaluated as a Mg source to supplement the CG based media used for lipid production by Chlorella vulgaris . By supplementing the process with 1 g/L of MgSO 4 , nearly 185.29 ± 4.53% improvement in lipid production has been achieved. Further, application of MgSO 4 nanoparticles was found to improve the lipid production by 118.23 ± 5.67%. Interestingly, unlike MgSO 4 , its nanoparticles were found to enhance the lipid production at the expense of only a small amount of glycerol. Thus, application of MgSO 4 nanoparticles could be a potential strategy for enhanced lipid yield. [ABSTRACT FROM AUTHOR]

The effect of different types of agitation (i) continuous agitation ( C); (ii) continuous, discontinuous, continuous agitation ( C/ D/ C); (iii) discontinuous, continuous, discontinuous agitation ( D/ C/ D) and aeration (0.87, 1.25, 1.66 vvm) on ligninolytic enzyme production and polyphenolic compounds extraction by solid-state cultures of Phanerochaete chrysosporium BKM- F-1767 was investigated. Higher production of manganese peroxidase ( Mn P) (1690.3 ± 87.6), lignin peroxidase ( Li P) (387.9 ± 14.3) and laccase (898.9 ± 53.3 U gds−1) and liberation of total polyphenolics (ranging from 12.22 ± 1.1 to 30.12 ± 0.88 mg gallic acid equivalents per gram DW) was obtained after 195, 147, 219 and 204 h of fermentation, respectively, using 1.66 vvm as airflow and ( C/ D/ C) agitation mode. Maximal enzyme production and total polyphenolic content were influenced by aeration, and higher values were obtained using 1.66 vvm as airflow rate, followed by 1.25 and 0.83 vvm, respectively. They were also influenced by agitation, and maximal values were obtained using C/ D/ C, followed by D/ C/ D and continuous agitation, respectively. The agitation modes influenced the production of ligninolytic enzymes and simultaneous extraction of polyphenols. [ABSTRACT FROM AUTHOR]

Rheological profile studies for apple pomace ultrafiltration sludge (APS) broth with filamentous fungus, Aspergillus niger NRRL-567 during citric acid (CA) fermentation are reported for the biomass developed in a 7.5 l bench scale fermentor. CA bioproduction of 23.67 ± 1.0 g/l APS and 40.34 ± 1.98 g/l APS was obtained in control (120 h) and in treatment with inducer, MeOH 3% ( v/v), respectively, after 132 h of fermentation by A. niger NRRL 567. The rheological properties of the fermentation broth including pellets were analyzed. The control demonstrated non-Newtonian pseudoplastic behaviour due to more filamentous growth. However, in treatment supplemented with inducer (methanol), pellet form was observed during fermentation with less viscous non-Newtonian broths. The power law model was followed with good confidence of fit (77.8-88.9%) throughout the fermentation in treatment with MeOH as an inducer. However, power law was followed with moderate fit of confidence (65.3-75.9%) at the beginning of fermentation until 48 h and later followed a good confidence of fit (75.9-88.2%) until 144 h of fermentation in control. Important rheological changes occurred in the broth during maximal CA production phase along with increase in biomass in the pelleted mycelium form. [ABSTRACT FROM AUTHOR]

Abstract: Solid-state citric acid fermentation was conducted in a 12-L rotating drum type bioreactor. The effect of inducers, ethanol and methanol were studied on citric acid bioproduction by Aspergillus niger NRRL 567 cultivated on apple pomace as a solid-substrate. Optimum conditions achieved for higher citric acid bioproduction (220.6±13.9g/kg dry solids, DS) were 3% (v/v) methanol, intermittent agitation of 1h after every 12h at 2rpm and 1vvm of aeration rate and 120h incubation time. The response surface optimization proved effective for higher citric acid extraction from fermented solid-substrate. Higher citric acid extraction of 294.19g/kg DS was achieved at optimum conditions: extraction time of 20min, agitation rate of 200rpm and extractant volume of 15ml by response surface methodology. [Copyright &y& Elsevier]