Validation of thermal composting process using olive mill solid waste for industrial scale cultivation of Agaricus bisporus

The production of a substrate containing destoned olive mill solid waste for the cultivation of Agaricus bisporus (Lange) Imbach on an industrial scale was studied. A standard mushroom compost (C) mainly made from straw and poultry manure was compared with the experimental compost (EC) containing the same ingredients as (C) but with added olive mill solid waste (10.6% w/w). Microbial indicators such as counts of heterotrophic microbes and actinomycetes were higher in EC than in C. In addition, compost selectivity as indicated by higher mushroom yield and biological efficiency of EC was higher than that of C. Market quality of the mushrooms produced in both C and EC were comparable. These findings support our work that olive mill solid waste can be used safely in thermal composting process to produce a selective substrate for industrial-scale cultivation of A. bisporus. This study also demonstrates an environmentally sustainable system to manage solid waste from olive oil extraction processes thus overcoming environmental pollution brought about by irrational disposal of the waste on farm lands.     

Feasibility of using olive mill effluent (OME) as a wetting agent during the cultivation of oyster mushroom, Pleurotus ostreatus, on wheat straw

In this study, cultivation of oyster mushroom, Pleurotus ostreatus, on wheat straw substrate containing tap water and olive mill effluent (OME) mixture containing varying volume of OME was studied in order to investigate the feasibility of using OME as an alternative wetting agent and OME's impact on some fundamental food quality characteristics of mushrooms. Time period for mycelial colonization, primordium initiation and first harvest were comparatively evaluated with the control group. It was shown that the use of OME and tap water mixture consisting of OME up to 25% volumetrically was possible for the purpose of commercial mushroom production. Experimental results obtained from substrate containing 25% OME mixture showed no statistically significant difference compared to control group. The negative effects of increasing volume of OME in the mixture were also indicated by bioefficiency, which was found to be 13.8% for substrates wetted with 100% OME, whereas bioefficiency was 53.6% for control group. Increasing volume of OME in the mixture resulted in deformation of fruit body shape, whereas no significant difference in food quality was observed due to the higher amount of OME. This work suggested that the use of OME up to 25% as moisturizer could be considered, especially for the locations having significant number of olive mills and mushroom producers, both as an environmentally friendly solution for the safe and ecological disposal of OME and a practical way for recovering OME's economic value thereby.     

Potential of kenaf (Hibiscus cannabinus L.) and corn (Zea mays L.) for phytoremediation of dredging sludge contaminated by trace metals

The potential of kenaf (Hibiscus cannabinus L.) and corn (Zea mays L.) for accumulation of cadmium and zinc was investigated. Plants have been grown in lysimetres containing dredging sludge, a substratum naturally rich in trace metals. Biomass production was determined. Sludge and water percolating from lysimeters were analyzed by atomic absorption spectrometry. No visible symptoms of toxicity were observed during the three- month culture. Kenaf and corn tolerate trace metals content in sludge. Results showed that Zn and Cd were found in corn and kenaf shoots at different levels, 2.49 mg/kg of Cd and 82.5 mg/kg of Zn in kenaf shoots and 2.1 mg/kg of Cd and 10.19 mg/kg in corn shoots. Quantities of extracted trace metals showed that decontamination of Zn and Cd polluted substrates is possible by corn and kenaf crops. Tolerance and bioaccumulation factors indicated that both species could be used in phytoremediation.     

Ligninolytic enzymes activities of Oyster mushrooms cultivated on OMW (olive mill waste) supplemented media, spawn and substrates

Ligninolytic enzymes activities (laccases, peroxidases (total, MnP and MiP) and aryl-alcohol oxidase (AAO)) were measured during the cultivation of six commercial Pleurotus sp. strains on MMP media, on cereal grains (spawn) and on straw substrates (the three commonly utilized cultivation steps to obtain fruiting bodies) supplemented with several concentrations of autoclaved (OMW) or gamma-irradiated (iOMW) olive mill waste. Results indicated that all the strains were able to grow on MMP media and spawn containing up to 30% OMW and iOMW and on straw substrates mixed with 50% OMW. None of the strains showed AAO activity and there was not a single strain which showed the highest laccases and peroxidases activities, independently of the utilized substrate. Pleurotus mycelia adjusted their enzymatic mechanisms depending on their variety, type of substrate, concentration of OMW or iOMW added. OMW was a better supplement to use than iOMW because OMW induced higher exo-enzymes activities.     

Olive mill wastes: Biochemical characterizations and valorization strategies

The olive mill waste generated from olive oil extraction is a major environmental issue, particularly in Mediterranean areas. The extraction of olive oil is achieved through discontinuous or continuous processes. The two processes yield three fractions: a solid residue and two liquid phases (oil and olive mill wastewater). The characterization of these two by-products showed that they are mainly composed of phenolic compounds, carbohydrates, organic acids and mineral nutrients variably distributed depending on the process employed and the agronomic practices. Untreated olive by-products discharged between November and March into the environment are a major ecological issue for olive oil-producing countries due to their high toxic organic loads, low pH, and high chemical and biological demands. In this context, recent research studies highlight on the treatment approaches and valorization options for dealing with olive mill waste residues, predominantly those allowing for the recovery of valuable natural components such as phenolic compounds, dietary fibers, animal feed, biofuel, biogaz, enzymes, polymers and other. The impact of the chemical heterogeneity and water content of olive mill by-products about these processes of valorization and bioconversion is discussed.     

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

The aims of the current study were to follow: (1) the capability of the edible mushroom Pleurotus ostreatus to degrade cell wall components and soluble phenols of the olive mill solid waste (OMSW), and improve it for ruminant nutrition (2) the fate of oil and the lipid-soluble compounds tocopherols, squalene and β-sitosterol in the fermented OMSW. A significant decrease in oil and lipid-soluble compounds with a concomitant shift in the fatty acid profile and degradation of soluble phenols took place already after 14 d. The utilization of lipids by the fungus shifted the degradation of the structural carbohydrates to a later stage, and significantly reduced the metabolizable energy of the OMSW. We propose that edible fungi with reduced lipase activity would preserve the energy and health promoting ingredients of the oil, and force the fungus to degrade structural carbohydrates, thus improving its digestibility.     

Radiation and fermentation treatment of cellulosic wastes

The effect of radiation pasteurization of sugar cane bagasse and rice straw and fermentation using various strains of fungi were studied for upgrading of cellulosic wastes. The initial contamination by fungi and aerobic bacteria both in bagasse and straw was high. The doses of 30 kGy for sterilization and 8 kGy for elimination of fungi were required. Irradiation effect showed that rice straw contained comparatively radioresistant microorganisms. It was observed that all the fungi (Hericium erinacium, Pleurotus djamor, Ganoderma lucidum, Auricularia auricula, Lentinus sajor-caju, Coriolus versicolor, Polyporus arcularius, Coprinus cinereus) grow extending over the entire substrates during one month after inoculation in irradiated bagasse and rice straw with 3% rice bran and 65% moisture content incubated at 30°C. Initially, sugar cane bagasse and rice straw substrates contained 39.4% and 25.9% of cellulose, 22.9% and 26.9% of hemicellulose, and 19.6% and 13.9% of lignin + cutin, respectively. Neutral detergent fibre (NDF) values decreased significantly in sugar cane bagasse fermented byG. lucidum, A. auricula andP. arcularius, and in rice straw fermented by all the 8 strains of fungi. Acid detergent fibre (ADF) values also decreased in bagasse and rice straw fermented by all the fungi.P. arcularius, H. erinacium, G. lucidum andC. cinereus were found to be the most effective strains for delignification of sugar cane bagasse.     

Mineral content of the fruiting bodies of Pleurotus sajor-caju (FR.) SINGER cultivated on different kinds of biomass

Pleurotus sajor-caju (FR. ) SINGER was cultivated on different organic wastes, namely sericulture waste, Populus deltoides MARSH , and Eupatorium adenophorum SPRENG . Paddy straw was taken as the control and all the data were compared with it. The mineral contents of the fruiting bodies of Pleurotus sajor-caju and the substrates on which the mushroom was grown were analyzed. Among the eight minerals determined (calcium, phosphorus, potassium, magnesium, sodium, iron, manganese and zinc), the potassium content was highest followed by phosphorus, magnesium and sodium. Analysis of the mineral contents of the substrates before cultivation had also been carried out. The mineral contents of the fruiting bodies of Pleurotus sajor-caju were found to be different on different substrates. It was also observed that the mineral contents of the fruiting bodies of Pleurotus sajor-caju increase when cultivated on substrates with higher mineral contents. The maximum mineral contents per 100 g of the substrates before cultivation were Ca – 347 mg; P – 151 mg; K – 1,805 mg; Na – 127 mg; Mg – 227 mg; Fe – 53 mg; Mn – 10 mg and zn – 3.1 mg. The mineral contents of the fruiting bodies of Pleurotus sajor-caju per 100 g ranged as follows: Ca – 25.1 mg to 35.3 mg; P – 448 mg to 602 mg; K – 2,146 mg to 2350 mg; Na – 139 mg to 229 mg; Mg – 153 mg to 224 mg; Fe – 9.74 mg to 20.75 mg; Mn – 2.5 mg to 4.0 mg and Zn – 2.2 mg to 3.1 mg.     

Chemical and spectroscopic analysis of olive mill waste water during a biological treatment

The treatment of olive mill waste water was studied on the laboratory scale. Physico-chemical analyses showed the final products had a mean pH of 5.4 without neutralisation and 5.7 when lime was added to the process. Raising the pH by adding lime had a positive outcome on the degradation of phenols, whose levels were reduced by over 76%. The lime also changed the structure of the organic matter, as seen in the infra-red spectra. Combining the FT-IR and 13C NMR data showed that with addition of lime, the density of aliphatic groups decreased to the benefit of aromatic groups, indicating that polymerisation of the organic matter occurred during the bioprocess. Under our experimental conditions, the biotransformation of olive mill waste water appears to favour the stabilisation of the organic matter through mechanisms analogous to those that lead to the formation of humus in the soil.     

The study of the aerobic bacterial microbiota and the biotoxicity in various samples of olive mill wastewaters (alpechin) during their composting process

Five different piles were prepared by mixing olive mill wastewater (alpechin) and alpechin sludge with two bulking agents (cotton waste and maize straw) and two organic wastes with high content of nitrogen (sewage sludge and poultry manure), which were composted by the Rutgers static pile composting system in a pilot plant. The aim of this work was to study the evolution of total nitrogen and different forms of organic matter and evaluate the variation in the aerobic bacterial microbiota present and biotoxicity during the composting process.In piles prepared with alpechin, the use of the maize straw as a bulking agent reduced the nitrogen losses whereas the use of sewage sludge, instead of poultry manure, with cotton waste originated the highest degradation of organic matter. In piles prepared with alpechin sludge a similar evolution of the composting process was observed. There were not great variations during composting in the aerobic bacterial microbiota present in the mixtures. However, the pile prepared with alpechin sludge and maize straw was only one to present bacteria capable of growing in alpechin, and the toxicity study showed that this was only present in the starting mixtures.     

Transgenic tobacco plants expressing a fungal laccase are able to reduce phenol content from olive mill wastewaters

A biotechnological approach was applied to reduce phenol content in olive mill wastewaters by transgenic tobacco plants. The cDNA laccase of poxC gene from Pleurotus ostreatus, carrying its own signal peptide for extracellular secretion, was transferred into the Nicotiana tabacum genome. Transgenic tobacco plants were obtained and the recombinant enzyme was secreted into the rhizosphere by the plant root apparatus, confirming the ability of the plant machinery to recognize the fungal POXC peptide signal leader appropriately as secretory tag. Total laccase activity assayed by ABTS in transgenic lines increased sharply compared to control plants. Moreover, plants cultivated in a hydroponic solution with the addition of olive mill wastewaters were able to reduce the total phenol content up to 70%.     

Lignocellulolytic enzyme activity,substrate utilization,and mushroom yield by <Emphasis Type="Italic">Pleurotus ostreatus</Emphasis> cultivated on substrate containing anaerobic digester solids

Solid waste from anaerobic digestion of litter from the commercial production of broiler chickens has limited use as fertilizer. Its disposal is a major problem for digester operators who are seeking alternative use for anaerobic digester solids, also referred to as solid waste (SW). The use of SW as substrates for the cultivation of Pleurotus ostreatus strain MBFBL400 was investigated. Lignocellulolytic enzymes activity, substrate utilization, and mushroom yield were evaluated in ten different substrate combinations (SCs) containing varying amounts of solid waste, wheat straw, and millet. Nutritional content of mushrooms produced on the different substrates was also determined. Substrates containing 70–80% wheat straw, 10–20% SW, and 10–20% millet were found to produce the highest mushroom yield (874.8–958.3 g/kg). Loss of organic matter in all SCs tested varied from 45.8% to 56.2%, which had positive correlation with the biological efficiency. Laccase, peroxidase, and carboxymethylcellulase (CMCase) activities were higher before fruiting, whereas xylanase showed higher activities after mushroom fruiting. SW increased the nutritional content in mushrooms harvested, and the combination of wheat straw and SW with millet significantly improved mushroom yield. Our findings demonstrated the possibility of utilizing anaerobic digester solids in mushroom cultivation. The application of SW as such could improve the financial gains in the overall economy of anaerobic digester plants.     

Olive orchard amended with two experimental olive mill wastes mixtures: effects on soil organic carbon, plant growth and yield

Amendments of olive orchard soil with two different preparations of olive mill solid waste (OMWMs) at the rate of 9tonha(-1) per year for five years in two different plots were compared with an industry standard soil amendment using urea. Both the OMWMs amendments showed significant increases in total organic carbon and humic substances in soil of approximately 40% and 58%, respectively, without negative effects on tree growth and yield. This work has shown that olive oil mill waste (OMW) can be recycled safely using the bioremediation system used in this study. We suggest that this system is particularly beneficial to organic farming and is an alternative solution to direct spreading of raw OMW on farm lands.     

侧耳属真菌经济利用的研究进展

侧耳属真菌分布广泛、是大型真菌中生物多样性最为丰富的类群之一。其含有丰富的多糖、蛋白质、氨基酸、脂肪酸等生物活性物质,在食品、保健和医药等方面具有广泛用途。侧耳属真菌通过产生木质素氧化酶、锰过氧化物酶和漆酶等酶类降解多环芳烃、染料、工农业废弃物等有害物,并广泛应用于纺织厂、造纸厂、橄榄油厂废水及城市废水的处理。同时,侧耳属是食用菌家族中利用基质最为广泛的真菌,可以多种农业、林业、轻工业等废弃物为基质进行栽培生产,且生物学效率较高,具重要农业生产应用价值。     

The cultivation and nutritional value of Pleurotus sajor-caju

Summary A method for the cultivation of Pleurotus sajorcaju on a relatively large scale using cotton waste as substrate has been developed, and the mushroom so obtained has higher protein content than and comparable carbohydrate content to Agaricus bisporus, Volvariella volvacea, Lentinus edodes and Pleurotus ostreatus. The crude fats, ash, energy value, vitamin and mineral contents are lower and yet the differences are not great. The biological efficiency from cotton waste compost is lower than that from straw compost, however, the former has the advantage of giving rather even yield over successive flushes. This mushroom has a high potential to be produced economically on a large scale in Hong Kong.     

Agroecological management of a soil‐dwelling orthopteran pest in vineyards

The efficacy of different combinations of undervine and inter‐row treatments for managing a soil‐dwelling orthopteran pest, weta (Hemiandrus sp.), in vineyards was investigated over 2 seasons. This insect damages vine buds, thus reducing subsequent grape yield. The undervine treatments comprised pea straw mulch, mussel shells, tick beans [Vicia faba Linn. var minor (Fab)], plastic sleeves on vine trunks (treated control) and control (no intervention), while inter‐rows contained either the existing vegetation or tick beans. Treatments were arranged in a randomized complete block design with 10 replicates. Data were collected on weta densities, damage to beans and components of yield. The latter were numbers of bud laid down per vine, shoots per bud, clusters per shoot, grape bunches per vine, bunch weight and yield. The undervine treatments significantly affected all variables except the number of shoots per bud. In contrast, none of the variables was significantly affected by the inter‐row treatments or their interaction with undervine treatments, apart from weta density. At the end of the experiment, weta density in the shell treatment was about 58% lower than in the control. As a result, there was about 39% significant yield increase in that treatment compared to the control. Although the undervine beans and sleeves treatments increased yield, there were no reductions in weta density. With undervine beans, the insect fed on the bean plants instead of vine buds. Thus, yield in that treatment was approximately 28% higher than in the control. These results demonstrate that simple agroecological management approaches can reduce above‐ground damage by soil‐dwelling insects.     

Solar pasteurization of straw for nutritional upgrading and as substrate for ligninolytic organisms

Summary Solar digesters were designed to wet pasteurize straw. Microbial levels were reduced, precluding competition with ligninolytic organisms. The pasteurization treatment alone increased the available cellulose by 20–40%. Ligninolytic organisms produced biomass with 6–8% protein on pasteurized wheat straw.     

Substrate-dependent degradation patterns in the decay of wheat straw and beech wood by ligninolytic fungi

Summary The ability of 45 fungal strains to degrade wheat straw and beech wood was studied. Degradation patterns were defined in terms of chemical evolution of substrates and changes in lignin and polysaccharides. Trametes versicolor produced an important degradation of lignin and increased substrate digestibility, but it caused high weight losses and gave rise to similar decay patterns on both substrates. A preferential degradation of lignin was produced during straw transformation by Pleurotus eryngii. The increase of soluble lignin and decreases of lignin content and H/C ratio defined the degradation tendency after principal component analysis. The cation exchange capacity and water and alkali solubility presented the highest loading factors for the characterization of fungal transformation of beech wood. Offprint requests to: A. T. Martínez     

Transformation parameters enhancing T-DNA expression in kenaf (Hibiscus cannabinus)

Kenaf(Hibiscus cannabinus)is a fast growing annual with tremendous potential as a source of fiber for ropes, textiles and paper. Kenaf is an environmentally friendly crop; however, commercial production of kenaf is hindered by weed competition at the seedling stage. Herbicide resistant kenaf cultivars would reduce seedling weed competion and make growing kenaf more profitable. Factors that are important in establishing a transformation system for kenaf were examined. The influence of Agrobacterium strain, temperature, host tissue wounding, acetosyringone, virG/virE genes and host cell division on T-DNA expression in the kenaf shoot apex were investigated. Three Agrobacterium strains were tested, and A. tumefaciens LBA4404 significantly (α=0.05) yielded a high number of shoots surviving on selection medium; no shoots survived with EHA101S or Z707S. There was no significant difference (α=0.05) in transient T-DNA expression between 28 °C and 25 °C; however, shoots did not survive 16 °C or 19 °C co-cultivation temperatures. Shoot apex survival was increased significantly (α=0.05) when virulence genes and a cytokinin, TDZ, were combined. Sonicated shoots showed an increase in transient expression and shoot survival. Optimal conditions for shoot apex T-DNA transfer and expression were sonication for 5 s, co-cultivation with LBA4404 containingvirG/virEat room temperature, and 200 μmol/L acetosyringone.     

Valorization of solid olive mill wastes by cultivation of a local strain of edible mushrooms

Olive oil industry generates huge quantities of solid olive mill wastes (SOMW), causing environmental damage. Cultivation of edible mushrooms, such as Pleurotus ostreatus is a valuable approach for SOMW valorization. A local strain mycelium (Tizi-Ouzou, Algeria) of P. ostreatus (LPO) was isolated from castor oil plants. Oyster mushroom spawn, produced on barley grains, was used to inoculate wet SOMW, steamed in a traditional steamer during 45 min. The mycelium growth rate on SOMW was first estimated in Petri dish by measuring the surface colonized by the mycelium. The fruit body yields were estimated on culture bags containing 2 kg each of SOMW inoculated at 7% (w/w). The local strain potential was compared with that of a commercial one. Both strains produced high-quality mushrooms, but with low yields. The supplementation of the SOMW with wheat straw at the rate of 10% and 2% of CaCO₃ had significantly enhanced the productivity of the two strains, multiplying it by 3.2 for LPO and by 2.6 for CPO.