The potential of Pleurotus-treated olive mill solid waste as cattle feed

From laboratory- to industrial-scale plants: Future of anaerobic digestion of olive mill solid wastes

In this review, the main properties of olive mill solid waste, the primary by-product of olive oil production, and its feasibility as a feedstock for anaerobic digesters operating at laboratory-, pilot- and industrial-scales are discussed in detail. Nutrient addition and thermal pretreatments were found to have the potential to address the challenges arising from the high carbon-to-nitrogen ratio, the low pH, and the high concentration of phenolic compounds. Furthermore, anaerobic co-digestion with different organic feedstocks has been identified as one of the most promising options to solve the aforementioned problems and the seasonality nature of olive waste, while improving the efficiency of anaerobic treatment plants that operate throughout the whole year. The insights generated from this study show co-digestion with wastes from animal farming to be the most environmentally and economically sustainable method for improving anaerobic digestion processes with olive mill solid waste.

Solid-State Fermentation with White Rot Fungi (Pleurotus Species) Improves the Chemical Composition of Highland Barley Straw as a Ruminant Feed and Enhances In Vitro Rumen Digestibility

Lignin degradation is important for enhancing the digestibility and improving the nutritive quality of ruminant feeds. White rot fungi are well known for their bioconversion of lignocellulosic biomass. The objective of this paper was to evaluate whether Lentinus sajor-caju, Pleurotus ostreatus, Phyllotopsis rhodophylla, Pleurotus djamor, Pleurotus eryngii, and Pleurotus citrinopileatus treatments altered the chemical compositions of highland barley straw constituents and enhanced their nutritional value as a ruminant feed. All white rot fungi significantly increased the relative crude protein (CP), ethyl ether extract (EE), starch, soluble protein (SP), and non-protein nitrogen (NPN) contents but decreased the ash, neutral detergent fiber (NDF), acid detergent fiber (ADF), acid detergent lignin (ADL), and acid detergent insoluble protein (ADFIP) contents. In addition, L. sajor-caju treatment increased (p < 0.001) the levels of PA, PB2, PB3, CA, CB1, CB2, and CNSC, but reduced (p < 0.001) the PC and CC in the solid-state fermentation of highland barley straw. Maximum ligninlysis (50.19%) was optimally produced in the presence of 1.53% glucose and 2.29% urea at 22.72 ℃. The in vitro dry matter digestibility and total volatile fatty acid concentrations of fermented highland barley straw, as well as the fermentability, were optimized and improved with L. sajor-caju, which degraded the lignocellulose and improved the nutritional value of highland barley straw as a ruminant feed.

Olive Industry Solid Waste-Based Biosorbent: Synthesis and Application in Wastewater Purification

In this work, we present a process for converting olive industry solid waste (OISW) into a value-added material with ionic receptors for use in the removal of toxic metal ions from wastewater. This 3D polymer is a promising adsorbent for large-scale application, since it is a low-cost material made from agricultural waste and showed exceptional performance. The synthesis of the network polymer involved the carboxymethylation of OISW and curing of the carboxymethylated OISW at an elevated temperature to promote the formation of ester linkages between OISW's components. FT-IR, atomic force microscopy, and thermal analysis were performed on the crosslinked product. The adsorption efficiency of the crosslinked carboxymethylated OISW toward Pb(II), Cu(II), and other toxic metal ions present in sewage was evaluated as a function of adsorbent dose, temperature, pH, time, and initial metal ion. The percentage removal of about 20 metal ions present in a sewage sample collected from a sewer plant located in the Palestinian Territories was determined. The adsorption efficiency did not drop even after six cycles of use. The kinetic study showed that the adsorption process follows the Langmuir isotherm model and the second-order adsorption rate. The experimental Qe values of 13.91 and 13.71 mg/g were obtained for Pb(II) and Cu(II) removal, respectively. The thermodynamic results confirm the spontaneous metal bonding to the receptor sites of the crosslinked carboxymethylated OISW.

Biological depolymerization of lignin using laccase harvested from the autochthonous fungus Schizophyllum commune employing various production methods and its efficacy in augmenting in vitro digestibility in ruminants

A laccase-producing hyper performer, Schizophyllum commune, a white-rot fungus, was evaluated for its ability to selectively degrade lignin of diverse crop residues in vitro. Relative analysis of crop residue treatment using laccase obtained from immobilized cells demonstrated degradation of 30-40% in finger millet straw and sorghum stover, 27-32% in paddy straw, 21% in wheat straw, and 26% in maize straw, while 20% lignin degradation was observed when purified and recombinant laccase was used. Further investigations into in vitro dry matter digestibility studies gave promising results recording digestibility of 54-59% in finger millet straw 33-36% in paddy straw and wheat straw, 16% in maize straw for laccase obtained from cell immobilization method, whereas 14% digestibility was observed when purified and recombinant laccase was used. Sorghum stover recorded digestibility of 13-15% across all straws treated with laccase. The results obtained elucidated the positive influence of laccase treatment on lignin degradation and in vitro dry matter digestibility. The present research gave encouraging figures confirming the production of laccase using the cell immobilization method to be an efficient production method commensurate with purified and recombinant laccase under conditions of submerged cultivation, proclaiming a cost-effective, environmentally safe green technology for effectual lignin depolymerization.

Nutritional value of commercial broiler feed supplemented with olive mill waste fermented with probiotic Rhizopus oryzae strains

AIMS

The changes in chemical composition and metabolizable energy of both olive mill waste (OMW) upon fermentation by three potential probiotic Rhizopus oryzae strains and commercial feed (CF) upon its supplementation by fermented olive mill waste (FOMW) were investigated. The objective was to test if there will be an enhancement in the nutritional value of olive mill waste after fermentation and/or commercial broiler feed upon supplementation by potentially probiotic filamentous fungi.

METHODS AND RESULTS

A three Rhizopus oryzae strains (92/1, 236/2, and 284) isolated from agricultural soil that were proven to have good probiotic properties (non-toxic, antimicrobial activity, antioxidant capacity, and gastrointestinal tolerance) were used to ferment OMW, then the chemical composition was analyzed after 7 and 14 days of fermentation. The FOMW with the R. oryzae 284 strain, which gave the best results, was added to a commercial broiler feed at 20%, 30%, and 40% supplementation ratios. Then proximal analyses were done to compare non-supplemented with supplemented CF. Chemical analyses included dry weight, crude protein, crude fats, crude fibers, crude ash, sugars, and starch, then metabolizable energy was calculated from the given values.

CONCLUSIONS

Compared to non-fermented OMW, the best results were obtained by the R. oryzae 284 strain allowing an increase in crude protein content by 23.4% after 7 days of fermentation, a decrease in crude fiber content by 9.8% after 14 days of fermentation, and an increase in metabolizable energy by 3.6% after 7 days of fermentation. Compared to non-supplemented CF, the metabolizable energy changes of 20, 30, and 40% supplementation increased by 8.38, 2.83%, and decreased by 4.27% respectively.

SIGNIFICANCE AND IMPACT OF STUDY

FOMW can be incorporated into broiler feed rations until 30% without causing any decrease in metabolizable energy. It can be a cheaper alternative with promising productivity and chicken health improvements.

Socio-Economic and Environmental Impacts of Biomass Valorisation: A Strategic Drive for Sustainable Bioeconomy

In the late twentieth century, the only cost-effective opportunity for waste removal cost at least several thousand dollars, but nowadays, a lot of improvement has occurred. The biomass and waste generation problems attracted concerned authorities to identify and provide environmentally friendly sustainable solutions that possess environmental and economic benefits. The present study emphasises the valorisation of biomass and waste produced by domestic and industrial sectors. Therefore, substantial research is ongoing to replace the traditional treatment methods that potentially acquire less detrimental effects. Synthetic biology can be a unique platform that invites all the relevant characters for designing and assembling an efficient program that could be useful to handle the increasing threat for human beings. In the future, these engineered methods will not only revolutionise our lives but practically lead us to get cheaper biofuels, producing bioenergy, pharmaceutics, and various biochemicals. The bioaugmentation approach concomitant with microbial fuel cells (MFC) is an example that is used to produce electricity from municipal waste, which is directly associated with the loading of waste. Beyond the traditional opportunities, herein, we have spotlighted the new advances in pertinent technology closely related to production and reduction approaches. Various integrated modern techniques and aspects related to the industrial sector are also discussed with suitable examples, including green energy and other industrially relevant products. However, many problems persist in present-day technology that requires essential efforts to handle thoroughly because significant valorisation of biomass and waste involves integrated methods for timely detection, classification, and separation. We reviewed and proposed the anticipated dispensation methods to overcome the growing stream of biomass and waste at a distinct and organisational scale.

Antioxidant and anti-ageing effects of enzymatic polysaccharide from Pleurotus eryngii residue

The wide industrial cultivation of Pleurotus eryngii (P. eryngii) has resulted in the massive production of mushroom residues (MR) with low-efficiency utilization. In the present study, the P. eryngii enzymatic residue polysaccharide (PERP) was obtained from the P. eryngii residues. The characterization analysis showed that PERP was polysaccharides comprised of five kinds of monosaccharides with molecular weight of 2.05 × 10³ Da. PERP also showed rough surface and appeared as spherical structure dispersed in aqueous solution. The animal experiment analysis demonstrated that PERP exhibited potential anti-ageing effects on the brain, liver, kidney and skin, possibly by scavenging reactive radicals, improving the antioxidant status, supressing lipid peroxidation, enhancing organ functions and ameliorating histopathological damage. These results may provide a reference for the efficient utilization of P. eryngii residues in exploring MR-derived functional foods or drugs that delay the ageing process.

Circular economy in olive oil production - Olive mill solid waste to ethanol and heavy metal sorbent using microwave pretreatment

Olive mill solid waste (OMSW) is an abundant agricultural waste without viable solution. The effects of OMSW different pretreatments (microwave or autoclave), different additives (water, formic, or sulfuric acid), and utilization of different saccharification enzymes (Cellic® CTec2 or Accellerase® 1500) were tested on saccharification process and sugar release, and on fermentation inhibitors formation and ethanol production. Microwave treatment with formic acid resulted in highest saccharification rates (90% of cellulose fraction) and fermentation yields (15.9 g/L ethanol), although loss of sugars and fermentation inhibitors production was notable. Microwave with water treatment resulted in less saccharification and ethanol (9.6 g/L). To facilitate economical process and to extract maximum value, solid remnants after saccharification were tested as heavy metal sorbent. Microwave with water resulted in the best sorbent, followed by microwave with formic acid. Addition of sulfuric acid, to either microwave or autoclave, resulted in very poor saccharification and absorbance capacity. Therefore, combination of ethanol and sorbent production from OMSW are suggested.

Production of biochar from olive mill solid waste for heavy metal removal

Commercial activated carbon (CAC) and biochar are useful adsorbents for removing heavy metals (HM) from water, but their production is costly. Biochar production from olive solid waste from two olive cultivars (Picual and Souri) and two oil production process (two- or three-phase) and two temperatures (350 and 450°C) was tested. The biochar yield was 24-35% of the biomass, with a surface area of 1.65-8.12m²g^-1, as compared to 1100m²g^-1 for CAC. Picual residue from the two-phase milling technique, pyrolysed at 350°C, had the best cumulative removal capacity for Cu⁺², Pb⁺², Cd⁺², Ni⁺² and Zn⁺² with more than 85% compared to other biochar types and CAC. These results suggest that surface area cannot be used as a sole predictor of HM removal capacity. FTIR analysis revealed the presence of different functional groups in the different biochar types, which may be related to the differences in absorbing capacities.

Olive Mill Waste Enhances α-Glucan Content in the Edible Mushroom Pleurotus eryngii

Mushroom polysaccharides are edible polymers that have numerous reported biological functions; the most common effects are attributed to β-glucans. In recent years, it became apparent that the less abundant α-glucans also possess potent effects in various health conditions. Here we explore several Pleurotus species for their total, β and α-glucan content. Pleurotus eryngii was found to have the highest total glucan concentrations and the highest α-glucans proportion. We also found that the stalks (stipe) of the fruit body contained higher glucan content then the caps (pileus). Since mushrooms respond markedly to changes in environmental and growth conditions, we developed cultivation methods aiming to increase the levels of α and β-glucans. Using olive mill solid waste (OMSW) from three-phase olive mills in the cultivation substrate. We were able to enrich the levels mainly of α-glucans. Maximal total glucan concentrations were enhanced up to twice when the growth substrate contained 80% of OMSW compared to no OMSW. Taking together this study demonstrate that Pleurotus eryngii can serve as a potential rich source of glucans for nutritional and medicinal applications and that glucan content in mushroom fruiting bodies can be further enriched by applying OMSW into the cultivation substrate.

Protective effects on liver, kidney and pancreas of enzymatic- and acidic-hydrolysis of polysaccharides by spent mushroom compost (Hypsizigus marmoreus)

The present work investigated the protective effects on liver, kidneys and pancreas of spent mushroom compost polysaccharide (SCP) and its hydrolysates (enzymatic- (ESCP) and acid-hydrolyzed SCP (ASCP)) from Hypsizigus marmoreus, in streptozotocin (STZ)-induced diabetic mice. The results showed that enzymatic (superoxide dismutase (SOD), glutathione peroxidase (GSH-Px) and catalase (CAT)) and non-enzymatic activities (total antioxidant capacity (T-AOC)) were significantly increased, the lipid peroxide contents (lipid peroxide (LPO) and malonaldehyde (MDA)) were remarkably reduced, and the clinical parameters were observably mitigated in diabetic mice treated with these three polysaccharides. Furthermore, histological observations also indicated recovery. These conclusions demonstrated that both SCP and its hydrolysates ESCP and ASCP possessed potent antioxidant activities and can be used as a potentially functional food for the prevention of diabetes and its complications induced by STZ.

In vitro utilization of lime treated olive cake as a component of complete feed for small ruminants

AIM

The current in vitro study was carried out to determine the chemical composition and inclusion level of lime treated olive cake on acid detergent fiber (ADF) replacement basis in adult male goats.

MATERIALS AND METHODS

Crude olive cake was collected and evaluated for proximate composition and protein fractionation. It was treated with 6% lime and incubated for 1 week under room temperature in 2 kg sealed polythene bags and was evaluated for proximate composition after incubation. Different isonitrogenous complete diets containing 0-50% of lime treated olive cake on ADF replacement basis were formulated as per the requirement of adult male goats. In ADF replacement, fiber and concentrate sources were replaced by lime treated olive cake by replacing the 0-50% ADF percentage of the total 40% ADF value of complete feed. The formulated complete diets were tested for in vitro degradation parameters.

RESULTS

Treatment of olive cake with 6% slaked lime increased availability of cellulose and alleviated digestibility depression caused by high ether extract percentage. Organic matter, nitrogen free extract, ADF and neutral detergent fiber were significantly lowered by lime treatment of olive cake. The cornell net carbohydrate and protein system analysis showed that non-degradable protein represented by acid detergent insoluble nitrogen (ADIN) was 21.71% whereas the non-available protein represented by neutral detergent insoluble nitrogen (NDIN) was 38.86% in crude olive cake. The in vitro dry matter degradation (IVDMD) values were comparable at all replacement levels. However, a point of inflection was observed at 40% ADF replacement level, which was supported by truly degradable organic matter (TDOM), microbial biomass production (MBP), efficiency of MBP and partitioning factor values (PF).

CONCLUSION

In our study, we concluded that there is comparable difference in composition of Indian olive cake when compared with European olive cake. The most important finding was that about 78% of nitrogen present in Indian olive cake is available to animal in contrary to that of European olive cake. We concluded from in vitro studies that Indian olive cake can be included in complete feed at 30% level (w/w; 40% ADF replacement) for feeding in small ruminants without compromising in vitro degradability of the feed.

Bioconversion of lignocellulosic residues by Agrocybe cylindracea and Pleurotus ostreatus mushroom fungi--assessment of their effect on the final product and spent substrate properties

Nine agro-industrial and forestry by-products were subjected to solid-state fermentation by Agrocybe cylindracea and Pleurotus ostreatus, and the process and end-products were comparatively evaluated. Grape marc waste plus cotton gin trash was the best performing medium for both fungi, while substrate composition had a marked effect on most cultivation parameters. Biological efficiency was positively correlated with nitrogen, lignin and ash, and negatively with hemicelluloses and carbohydrate content of substrates. Spent substrates demonstrated high reductions in hemicelluloses and cellulose in contrast to lignin; fibre fractions were correlated with nitrogen, fat and ash content of initial materials, while residual mycelial biomass was affected by mushroom productivity. Mushroom proximate analysis revealed significant variations of constituents depending on the substrate. Crude protein and fat were correlated with substrates nitrogen for both species. Alternative cultivation substrates of high potential are proposed, while spent material could be exploited as animal feed due to its upgraded properties.

Degradation and selective ligninolysis of wheat straw and banana stem for an efficient bioethanol production using fungal and chemical pretreatment

Lignocelluloses from agricultural, industrial, and forest residues constitute a majority of the total biomass present in the world. Environmental concerns of disposal, costly pretreatment options prior to disposal, and increased need to save valuable resources have led to the development of value-added alternate technologies such as bioethanol production from lignocellulosic wastes. In the present study, biologically pretreated (with the fungus, Pleurotus ostreatus HP-1) and chemically pretreated (with mild acid or dilute alkali) wheat straw (WS) and banana stem (BS) were subsequently subjected to enzymatic saccharification (with mixture of 6.0 U/g of filter paper cellulase and 17 U/g of β-glucosidase) and were evaluated for bioethanol production using Saccharomyces cerevisiae NCIM 3570. Biological and chemical pretreatments removed up to 4.0–49.2 % lignin from the WS and BS which was comparatively higher than that for cellulose (0.3–12.4 %) and for hemicellulose (0.7–21.8 %) removal with an average 5.6–49.5 % dry matter loss. Enzymatic hydrolysis yielded 64–306.6 mg/g (1.5–15 g/L) reducing sugars from which 0.15–0.54 g/g ethanol was produced from Saccharomyces cerevisiae NCIM 3570.

Raw and fungal-treated olive-mill wastewater effects on selected parameters of lettuce (Lactuca sativa L.) growth--the role of proline

Olive-mill wastewater (OMW) constitutes a major agricultural waste stream for which disposal is associated with significant environmental repercussions. No data are available on the effects of biotreated OMW and of the protective role of exogenously provided proline on plant physiology. In the present study, OMW was administered, either raw or previously treated by the white-rot fungus Pleurotus ostreatus, with or without proline amendment, to lettuce plants growing in sterilized sand. Biotreated OMW and proline addition resulted in significant moderation of OMW adverse effects on plant biomass production and ascorbic acid content, while their synergistic action alleviated the severe negative impact on net photosynthetic rate, water use efficiency and photosynthetic activity (Fv/Fo) invoked by the effluent. Moreover, biotreated OMW supplemented with proline, moderated the decrease in chlorophylls exerted by raw OMW, but it did not contribute at restoring carotenoids content. Restoration of plant transpiration was complete when biotreated OMW was used (with or without proline); proline alone mitigated the negative impact of OMW on photosynthetic efficiency (Fv/Fm and Fv'/Fm'). It seems that key photosynthetic parameters could be exploited as suitable evaluators of wastewater-induced plant toxicity, while plant fertigation with biotreated and/or supplemented OMW could be an interesting prospect in valorizing this effluent.