Biotechnological Utilization of Agro-Industrial Residues and By-Products-Sustainable Production of Biosurfactants

The importance and interest in the efficient use and valorization of agro-industrial residues and by-products have grown due to environmental problems associated with improper disposal. Biotechnological production processes, including microbial biosurfactant production, represent a sustainable way to utilize agro-industrial residues and by-products, which are applied as substrates in these processes. Biosurfactants produced by microorganisms using renewable resources are a viable alternative to traditional petrochemical surfactants and have several potential uses in a wide range of industrial sectors due to their minimal ecotoxicity, easy biodegradability, and moderate production conditions. The common applications of biosurfactants, besides in food industry as food additives and preservatives, are in agriculture, environmental protection, the cosmetics and pharmaceutical industry, wastewater treatment, the petroleum industry, etc. This review aims to summarize the comprehensive scientific research related to the use of various agro-industrial residues and by-products in the microbial production of biosurfactants, as well as to emphasize the present state and the importance of their sustainable production. Additionally, based on the available biosurfactant market analysis datasets and research studies, the current situation in science and industry and the future perspectives of microbial biosurfactant production have been discussed.

Mechanical Performance of Rotationally Molded Multilayer mLDPE/Banana-Fiber Composites

The incorporation of materials different from the polymer within the rotational molding process usually results in lowered mechanical properties, where impact strength is of particular concern. In order to overcome this issue, multilayer structures of virgin polyethylene (PE) and banana fiber composites were prepared to determine the impact of the different layers on the performance of the final part. Cycle time has been studied to identify the influence of the addition of fibers in the process. The tensile, flexural and impact properties have been analyzed, finding improvements in Young's modulus of up to 13%, although at the expense of significant decreases in impact strength. A reduction in the fiber size due to the pulverization process was observed, which affected the rheological and mechanical behavior of the composite. The beneficial effects of working in multiple layers have been demonstrated in this work, where composites with up to 5% of banana fiber have been produced in two-layer structures. Finally, the need to add neat polyethylene in the external layer is also highlighted as a way to counteract the reductions in mechanical properties, particularly for flexural elastic modulus and tensile strength, and this also helps with the drop in impact behavior to a lower extent.

Thermal Treatment to Obtain 5-Hydroxymethyl Furfural (5-HMF), Furfural and Phenolic Compounds from Vinasse Waste from Agave

Vinasses represent important final disposal problems due to their physical-chemical composition. This work analyzed the composition of tequila vinasses and increased 5-hydroxymethylfurfural, furfural, and phenolic compounds using thermal hydrolysis with hydrogen peroxide as a catalyst. A statistical Taguchi design was used, and a UPLC-MS (XEVO TQS Micro) analysis determined the presence and increase of the components. The treatment at 130 °C, 40 min, and 0.5% of catalyst presented the highest increase for 5-HMF (127 mg/L), furfural (3.07 mg/L), and phenol compounds as chlorogenic (0.36 mg/L), and vanillic acid (2.75 mg/L). Additionally, the highest removal of total sugars (57.3%), sucrose (99.3%), and COD (32.9%). For the treatment T130:30m:0P the syringic (0.74 mg/L) and coumaric (0.013 mg/L) acids obtained the highest increase, and the treatment T120:30m:1P increased 3-hydroxybenzoic (1.30 mg/L) and sinapic (0.06 mg/L) acid. The revaluation of vinasses through thermal treatments provides guidelines to reduce the impact generated on the environment.

Identification of Secondary Metabolites of Interest in Pleurotus djamor Using Agave tequilana Bagasse

Agro-industrial residues represent more than 60% of organic wastes worldwide, which could be used to generate other by-products or to be incorporated into other production chains. For example, bagasse is a waste from the tequila industry in Mexico that could be implemented for mushroom cultivation. Additionally, the substrate influences the growth, development, and production of secondary metabolites of fungi. This work presents a comparative experiment that studies the metabolite production in Pleurotus djamor mushrooms on agave bagasse and barley straw (traditional substrate). The biological efficiency (BE), yield, phenolics and flavonoids, antioxidant capacity, tannins, and the identification of low molecular weight metabolites were evaluated. Five treatments were proposed according to the following mixtures of agave bagasse: barley straw: T1 (1:0), T2 (3:1), T3 (1:1), T4 (1:3), and T5 (0:1). T2 had the highest yield (13.39 ± 3.23%), BE (56.7 ± 13.71%), and flavonoids (44.25 mg rutin equivalent (RE)/g); T3 obtained the highest phenol content (230.27 mg GAE/g); and T1 the highest tannins content (0.23 mg (+) catechin equivalent (CE)/g). Finally, T1 and T5 are the ones that present the greatest number of primary metabolites, including hydroxycitric acid, 2-deoxy-D-galactose, D-mannose, paromomycin, palmitic acid, pyrrole, mannitol, and DL arabinose, while in T2, T3, and T4 only two chemical compounds were found present (palmitic acid and pyrrole in T2, silicic acid and pyrrole in T3 and 2-deoxy-D-galactose and quinoline in T4). The cultivation substrate influences the concentration of bioactive molecules in the fruiting bodies of P. djamor. Additionally, P. djamor's degradation of agave bagasse residue generates a potential application for agro-industrial residue management at a low cost.

Biotechnological Production of Sustainable Microbial Proteins from Agro-Industrial Residues and By-Products

Microbial proteins, i.e., single-cell proteins or microbial biomass, can be cultivated for food and animal feed due to their high protein content and the fact that they represent a rich source of carbohydrates, minerals, fats, vitamins, and amino acids. Another advantage of single-cell proteins is their rapid production due to the growth rate of microorganisms and the possibility of using agro-industrial waste, residues and by-products for production through this renewable technology. Agro-industrial residues and by-products represent materials obtained from various processes in agriculture and agriculture-related industries; taking into account their composition and characteristics, as well as vast amounts, they have an enormous potential to generate sustainable bioproducts, such as microbial proteins. This review aims to summarize contemporary scientific research related to the production of microbial proteins on various agro-industrial residues and by-products, as well as to emphasize the current state of production of single-cell proteins and the importance of their production to ease the food crisis and support sustainable development.

Sustainable Exopolysaccharide Production by Rhizobium viscosum CECT908 Using Corn Steep Liquor and Sugarcane Molasses as Sole Substrates

Microbial exopolysaccharides (EPS) are promising alternatives to synthetic polymers in a variety of applications. Their high production costs, however, limit their use despite their outstanding properties. The use of low-cost substrates such as agro-industrial wastes in their production, can help to boost their market competitiveness. In this work, an alternative low-cost culture medium (CSLM) was developed for EPS production by Rhizobium viscosum CECT908, containing sugarcane molasses (60 g/L) and corn steep liquor (10 mL/L) as sole ingredients. This medium allowed the production of 6.1 ± 0.2 g EPS/L, twice the amount produced in the standard medium (Syn), whose main ingredients were glucose and yeast extract. This is the first report of EPS production by R. viscosum using agro-industrial residues as sole substrates. EPS_CSLM and EPS_Syn exhibited a similar carbohydrate composition, mainly 4-linked galactose, glucose and mannuronic acid. Although both EPS showed a good fit to the Herschel-Bulkley model, EPS_CSLM displayed a higher yield stress and flow consistency index when compared with EPS_Syn, due to its higher apparent viscosity. EPS_CSLM demonstrated its potential use in Microbial Enhanced Oil Recovery by enabling the recovery of nearly 50% of the trapped oil in sand-pack column experiments using a heavy crude oil.

Improvement of endoglucanase production by Aspergillus brasiliensis in solid-state fermentation using cupuaçu (Theobroma grandiflorum) residue as substrate

AIMS

Optimize the production of Aspergillus brasiliensis endoglucanase in a solid-phase bioprocess using cupuaçu shell as substrate.

METHODS AND RESULTS

The shells were supplemented with nitrogen and phosphorous and used as a substrate. The centesimal and inorganic composition of the residue was determined, and found to be rich in fibres, and possessed essential elements for fungal growth. In the initial cultivation of A. brasiliensis, endoglucanase activity of 7.35 U g^-1 was obtained. A factorial experimental design was used to determine the most significant variables for the bioprocess. The interactions between moisture, temperature and nitrogen source were noteworthy (p < 0.05). From the rotational central composite design, the optimization of temperature and nitrogen supplementation was obtained, and this reached 40.50 U g^-1 , which is an increase of more than five times the value obtained initially. The enzymatic extract was applied as the biocatalyst in the hydrolysis of cupuaçu shells and, after 48 h, it was possible to observe the production of reducing sugars.

CONCLUSIONS

Cupuaçu shell can be used as a substrate for endoglucanase production by A. brasiliensis. The process was optimized for the cultivation temperature and the nitrogen source. The enzymatic extract can be applied in the hydrolysis of lignocellulosic biomass.

SIGNIFICANCE AND IMPACT OF THE STUDY

Cupuaçu shells can be used to produce cellulases, a product of high added value that can generate economic and environmental benefits for communities and companies producing derivatives of the cupuaçu fruit.

Bioaccessibility of Anthocyanins on in vitro Digestion Mmodels: Factors Implicated and Role in Functional Foods Development

BACKGROUND

Worldwide, the prevalence of obesity and related non-communicable chronic diseases is high and continues to grow. In that sense, anthocyanins (ANC) have shown beneficial health effects in preventing obesity and metabolic risk factors. Moreover, the demand for functional foods incorporating these compounds has risen significantly in the past years. Thus, there is a need for validations of the functional properties of these formulations; nevertheless, in vivo assays are complex and require a lot of resources. One approach for estimating bioactive compounds' functionality and health benefits is to evaluate their bioaccessibility on a specific food matrix, determined by various factors. This article aims to review different factors influencing the bioaccessibility of ANC evaluated on in vitro digestion models as a functionality parameter, elucidating the effect of chemical composition, raw materials, food matrices, and vehicles for the delivery of ANC.

METHODS

Study searches were performed using PubMed, Web of Science, Scopus, and Science Direct databases.

RESULTS

Different factors influenced bioaccessibility and stability of ANC studied by in vitro digestion which are: i) the raw material used for ANC obtention; ii) food processing; iii) other food components; iv) the extraction method and solvents used; v) the structure of ANC; vi) delivery system (e.g., microencapsulation); vii) pH of the medium; viii) the digestion stage.

CONCLUSION

Simulated digestion systems allow to determine free or encapsulated ANC bioaccessibility in different food matrices, which offers advantages in determining the potential functionality of a food product.

Ionizing Radiation Technologies to Increase the Extraction of Bioactive Compounds from Agro-Industrial Residues: A Review

Due to the growing demand in society for healthier foods, scientific communities are searching and developing new ingredients. In this context, agro-industrial residues, which can have a negative impact on the environment, represent a natural source for bioactive compounds and their recovery can contribute to economic and environmental sustainability. Ionizing radiation is a clean and eco-friendly technology that can be used to improve the extraction of bioactive compounds. The aim of this review, after presenting general aspects about bioactive compounds in agro-industrial residues and radiation technologies, is to focus on the effects of ionizing radiation on the extraction of bioactive compounds from these residues and related bioactive properties. Irradiated residues were demonstrated to have enhanced bioactive characteristics that turn the prepared extracts suitable for applications in food industry, resulting in high-added-value products as well as reducing adverse impacts on the environment.

Kinetic study and characterization of surfactin production by Bacillus subtilis UFPEDA 438 using sugarcane molasses as carbon source

The present study evaluated the surfactin production by Bacillus subtilis UFPEDA 438 using sugarcane molasses as a substrate. The effects of the cultivation conditions (temperature, agitation and aeration ratio) on the biosurfactant production and kinetic parameters were investigated. Characteristics of the biosurfactant were obtained after analyses of the emulsification index (EI) and critical micellar concentration (CMC) of the fermentation broth. The results showed that in relation to the product its formation kinetics is strongly affected by operational conditions. It was also observed that surfactin production can be partially dependent or fully independent on microbial growth. The maximum values of surfactin concentration (199.45 ± 0.13 mg/L) and productivity (8,187 mg/L.h) were obtained in the culture under cultivation time of 24 h, temperature of 36 °C, agitation of 100 rpm and aeration ratio of 0.4. Under optimal conditions, the fermentation broth achieved good emulsification capacity (EI >40%) and CMC value of 20.73 mg/L. The results revealed that Bacillus subtilis UFPEDA 438 is a good producer of biosurfactant and that sugarcane molasses is a viable substrate for the production of surfactin.

Production of xylanases by Bacillus sp. TC-DT13 in solid state fermentation using bran wheat

Xylanases have gained increasing importance due to their diverse applications in the food, paper, and pharmaceutical industries, however, the production of these enzymes currently uses expensive substrates. It has already been estimated that more than 30% of the enzyme production cost originates from the substrate. The present study aimed to optimize the production of extracellular xylanases by the Bacillus sp. TC-DT 13 using solid-state fermentation with agro-industrial residues, with a view at reducing the production cost of these enzymes. All the agro-industrial residues were tested in submerged fermentation to select the best inductor to produce xylanase. Among these residues, wheat bran was selected as the best inducer of xylanase production with 1500 U/mL. Regarding solid-state fermentation, the use of wheat bran as the only fermentation substrate was used and a ratio of 1:4 moisture over a time of 144 hours induced higher amount of xylanase reaching 2943 U/g. The use of carbon and nitrogen sources did not result in the increase in production of xylanolitic enzymes. The use of agro-industrial residues in the solid-state fermentation, besides increasing the production of xylanase, reduces the cost of production and is an environmentally friendly alternative.

Potential of Physalis peruviana calyces as a low-cost valuable resource of phytoprostanes and phenolic compounds

BACKGROUND

In Colombia, agro-industrial residues represent an enormous economic and environmental problem, which could be reduced if different techniques for the addition of value to such residues were implemented by this industrial sector. One of the fruits with the highest export rates is Physalis peruviana (goldenberry); however, this fruit is generally marketed without its calyx, generating a large amount of residues. To develop a strategy to add value to these residues, it is essential to know their chemical composition.

RESULTS

In the present work, phytoprostanes (PhytoPs) - new active oxylipins - have been detected for the first time in Physalis peruviana calyces by ultra-high performance liquid chromatography triple quadrupole tandem mass spectrometry (UHPLC-QqQ-MS/MS), F_1t -phytoprostanes and D_1t -phytoprostanes being the predominant and minor classes, respectively. In addition, we were able to characterize the phenolic compounds profile of this matrix using LC-IT-DAD-MS/MS, describing six phenolic derivatives for the first time therein.

CONCLUSIONS

This study increases our knowledge of the chemical composition of the calyces of this fruit and thereby supports the recycling of this class of residue. Consequently, goldenberry calyces could be used as phytotherapeutic, nutraceutic, or cosmetic ingredients for the development of diverse natural products. © 2018 Society of Chemical Industry.

Valorization of agro-industrial wastes to produce hydrolytic enzymes by fungal solid-state fermentation

Nowadays, significant amounts of agro-industrial wastes are discarded by industries; however, they represent interesting raw materials for the production of high-added value products. In this regard, orange peels (ORA) and exhausted sugar beet cossettes (ESBC) have turned out to be promising raw materials for hydrolytic enzymes production by solid state fermentation (SSF) and also a source of sugars which could be fermented to different high-added value products. The maximum activities of xylanase and exo-polygalacturonase (exo-PG) measured in the enzymatic extracts obtained after the SSF of ORA were 31,000 U·kg^-1 and 17,600 U·kg^-1, respectively; while for ESBC the maximum values reached were 35,000 U·kg^-1 and 28,000 U·kg^-1, respectively. The enzymatic extracts obtained in the SSF experiments were also employed for the hydrolysis of ORA and ESBC. Furthermore, it was found that extracts obtained from SSF of ORA, supplemented with commercial cellulase, were more efficient for the hydrolysis of ORA and ESBC than a commercial enzyme cocktail typically used for this purpose. In this case, maximum reducing sugars concentrations of 57 and 47 g·L^-1 were measured after the enzymatic hydrolysis of ESBC and ORA, respectively.

Comparative evaluation of extracellular β-d-fructofuranosidase in submerged and solid-state fermentation produced by newly identified Bacillus subtilis strain

AIMS

To screen and identify a potential extracellular β-d-fructofuranosidase or invertase-producing bacterium from soil, and comparatively evaluate the enzyme biosynthesis under submerged and solid-state fermentation (SSF).

METHODS AND RESULTS

Extracellular invertase-producing bacteria were screened from soil. Identification of the potent bacterium was performed based on microscopic examinations and 16S rDNA molecular sequencing. Bacillus subtilis LYN12 invertase secretion was surplus with wheat bran humidified with molasses medium (70%), with elevated activity at 48 h and 37°C under SSF, whereas under submerged conditions, increased activity was observed at 24 h and 45°C in the molasses medium. The study revealed a simple fermentative medium for elevated production of extracellular invertase from a fast growing Bacillus strain.

CONCLUSIONS

Bacterial invertases are scarce and limited reports are available. By far, this is the first report on the comparative analysis of optimization of extracellular invertase synthesis from B. subtilis strain by submerged and SSF. The use of agricultural residues increased yields resulting in the development of a cost-effective and stable approach.

SIGNIFICANCE AND IMPACT OF THE STUDY

Bacillus subtilis LYN12 invertase possesses excellent fermenting capability to utilize agro-industrial residues under submerged and solid-state conditions. This could be a beneficial candidate in food and beverage processing industries.

Biotechnological potential of agro-industrial waste in the synthesis of pectin lyase from Aspergillus brasiliensis

This study aims at investigating pectin lyase bioproduction in submerged fermentation with synthetic medium and agro-industrial residues, using the filamentous fungus Aspergillus brasiliensis. The maximum pectin lyase activity in a synthetic medium (42 g/l pectin, 40 g/l yeast extract, and 0.02 g/l iron sulfate) was 31 U/ml, and 46 U/ml in the agro-industrial medium (160 g/l orange peel, 150 g/l corn steep liquor, and 300 g/l parboiled rice water), obtained over 60 and 124 h of bioproduction, 180 r/min, 30 ℃, pH_initial 5.5, and 5·10⁶ spores/ml, respectively. Partial characterization of pectin lyase crude enzyme extract obtained from the synthetic medium and the one made of agro-industrial residues showed optimum conditions at pH of 5.5 and 4.5 and temperatures of 37 and 55 ℃, respectively. The E_d obtained was 3.13 and 9.15 kJ/mol, and the half-life time (t_1/2) was 5.71 and 80 h at 55 ℃ for pectin lyase produced in synthetic and agro-industrial medium, respectively.

Extracellular Alkaline Lipase from a Novel Fungus Curvularia sp. DHE 5: Optimisation of Physicochemical Parameters, Partial Purification and Characterisation

Thirty isolated fungal strains were screened for lipase production using Phenol Red plates, containing tributyrin as lipidic substrate, and a novel fungus identified genetically as Curvularia sp. DHE 5 was found as the most prominent strain. Various agro-industrial substrates were evaluated as inert supports for lipase production in solid-state fermentation. The highest yield of lipase ((83.4±2.2) U/g on dry mass basis) was reported with wheat bran medium after seven days of fermentation at pH=7.0, temperature of 30 °C, 70% moisture content, inoculum size of 1.27·10⁷ spore/mL and 2% olive oil as an inducer. Supplementation of the medium with 0.05% KCl as an ion source further increased lipase production to (88.9±1.2) U/g on dry mass basis. The enzyme was partially purified through ammonium sulphate fractionation (40%) followed by dialysis, and its optimum pH and temperature were reported at 8.0 and 50 °C, respectively, with remarkable pH and thermal stability.

Bioprocessing of some agro-industrial residues for endoglucanase production by the new subsp.; Streptomyces albogriseolus subsp. cellulolyticus strain NEAE-J

The use of low cost agro-industrial residues for the production of industrial enzymes is one of the ways to reduce significantly production costs. Cellulase producing actinomycetes were isolated from soil and decayed agricultural wastes. Among them, a potential culture, strain NEAE-J, was selected and identified on the basis of morphological, cultural, physiological and chemotaxonomic properties, together with 16S rDNA sequence. It is proposed that strain NEAE-J should be included in the species Streptomyces albogriseolus as a representative of a novel sub-species, Streptomyces albogriseolus subsp. cellulolyticus strain NEAE-J and sequencing product was deposited in the GenBank database under accession number JN229412. This organism was tested for its ability to produce endoglucanase and release reducing sugars from agro-industrial residues as substrates. Sugarcane bagasse was the most suitable substrate for endoglucanase production. Effects of process variables, namely incubation time, temperature, initial pH and nitrogen source on production of endoglucanase by submerged fermentation using Streptomyces albogriseolus subsp. cellulolyticus have been studied. Accordingly optimum conditions have been determined. Incubation temperature of 30 °C after 6 days, pH of 6.5, 1% sugarcane bagasse as carbon source and peptone as nitrogen source were found to be the optimum for endoglucanase production. Optimization of the process parameters resulted in about 2.6 fold increase in the endoglucanase activity. Therefore, Streptomyces albogriseolus subsp. cellulolyticus coud be potential microorganism for the intended application.