Membrane bioreactor assisted volatile fatty acids production from agro-industrial residues for ruminant feed application.

Volatile fatty acids (VFAs) supplementation in ruminants' diet as a source of energy and chemical precursors and their effect on animal's physiology and well-being has long been of scientific interest. Production of VFAs through anaerobic digestion of agro-industrial residues not only creates value but also presents an alternative sustainable approach for ruminant feed supplementation. Therefore, this study aimed to investigate the bioconversion of agro-industrial residues produced in large quantities such as apple pomace (AP), thin stillage (Ts), and potato protein liquor (PPL) to VFAs, fully complying to regulations set for ruminant feed supplement production. In this regard, batch acidogenic fermentation assays (pH 6-10) and semi-continuous immersed membrane bioreactor (iMBR) were applied. In batch assays, at pH 10 the co-digestion of Ts and PPL produced the highest VFAs concentration (14.2 g/L), indicating a yield of 0.85 g CODVFAs/g volatile solids (VS)added. The optimum batch condition was then applied in the iMBR for in situ fermentation and recovery of VFAs at different organic loading rates (OLR). With increasing the OLR to 3.7 gVS/L.day, the highest VFAs concentration of 28.6 g/L (1,2 g CODVFAs /gVSadded) was achieved. Successful long-term (114 days) membrane filtration was conducted in a media with a maximum of 40 g/L of total solids (TS), facing irreversible membrane fouling in the final stages. Acidogenic fermentation using an iMBR has the potential to play an important role in the future of feed additive provision through the biorefining of agro-industrial wastes via the carboxylate platform, given the role of VFAs production from organic residues.

Filamentous fungi for sustainable vegan food production systems within a circular economy: Present status and future prospects.

Filamentous fungi serve as potential candidates in the production of different value-added products. In the context of food, there are several advantages of using filamentous fungi for food. Among the main advantages is that the fungal biomass used food not only meets basic nutritional requirements but that it is also rich in protein, low in fat, and free of cholesterol. This speaks to the potential of filamentous fungi in the production of food that can substitute animal-derived protein sources such as meat. Moreover, life-cycle analyses and techno-economic analyses reveal that fungal proteins perform better than animal-derived proteins in terms of land use efficiency as well as global warming. The present article provides an overview of the potential of filamentous fungi as a source of food and food supplements. The commercialization potential as well as social, legal and safety issues of fungi-based food products are discussed.

Sustainable strategies for combating hydrocarbon pollution: Special emphasis on mobil oil bioremediation.

The global rise in industrialization and vehicularization has led to the increasing trend in the use of different crude oil types. Among these mobil oil has major application in automobiles and different machines. The combustion of mobil oil renders a non-usable form that ultimately enters the environment thereby causing problems to environmental health. The aliphatic and aromatic hydrocarbon fraction of mobil oil has serious human and environmental health hazards. These components upon interaction with soil affect its fertility and microbial diversity. The recent advancement in the omics approach viz. metagenomics, metatranscriptomics and metaproteomics has led to increased efficiency for the use of microbial based remediation strategy. Additionally, the use of biosurfactants further aids in increasing the bioavailability and thus biodegradation of crude oil constituents. The combination of more than one approach could serve as an effective tool for efficient reduction of oil contamination from diverse ecosystems. To the best of our knowledge only a few publications on mobil oil have been published in the last decade. This systematic review could be extremely useful in designing a micro-bioremediation strategy for aquatic and terrestrial ecosystems contaminated with mobil oil or petroleum hydrocarbons that is both efficient and feasible. The state-of-art information and future research directions have been discussed to address the issue efficiently.

Cultivation of edible filamentous fungus Aspergillus oryzae on volatile fatty acids derived from anaerobic digestion of food waste and cow manure.

In a circular economy approach, edible filamentous fungi (single cell protein) can be cultivated on volatile fatty acids (VFAs) derived from anaerobic digestion (AD) of organic-rich waste streams. In this study, the effect of pH, concentration/distribution of VFAs, nutrient supplementation, and type of waste on Aspergillus oryzae cultivation on synthetic VFAs, and actual VFAs derived from AD of food waste and cow manure were investigated. The optimal pH for A. oryzae growth on VFAs were 6 and 7 with maximum acetic acid consumption rates of 0.09 g/L.h. The fungus could thrive on high concentrations of acetic (up to 9 g/L) yielding 0.29 g dry biomass/gVFAsfed. In mixed VFAs cultures, A. oryzae primarily consumed caproic and acetic acids reaching a biomass yield of 0.26 g dry biomass/gVFAsfed (containing up to 41% protein). For waste-derived VFAs at pH 6, the fungus successfully consumed 81-100% of caproic, acetic, and butyric acids.

Can biochar regulate the fate of heavy metals (Cu and Zn) resistant bacteria community during the poultry manure composting?

In this study, the influence of coconut shell biochar addition (CSB) on heavy metals (Cu and Zn) resistance bacterial fate and there correlation with physicochemical parameters were evaluated during poultry manure composting. High-throughput sequencing was carried out on five treatments, namely T1-T5, where T2 to T5 were supplemented with 2.5%, 5%, 7.5% and 10% CSB, while T1 was used as control for the comparison. The results of HMRB indicated that the relative abundance of major potential bacterial host altered were Firmicutes (52.88-14.32%), Actinobacteria (35.20-4.99%), Bacteroidetes (0.05-15.07%) and Proteobacteria (0.01-20.28%) with elevated biochar concentration (0%-10%). Beta and alpha diversity as well as network analysis illustrated composting micro-environmental ecology with exogenous additive biochar to remarkably affect the dominant resistant bacterial community distribution by adjusting the interacting between driving environmental parameters with potential host bacterial in composting. Ultimately, the amendment of 7.5% CSB into poultry manure composting was able to significantly reduce the HMRB abundance, improve the composting efficiency and end product quality.

Efficacy of polyextremophilic Aeribacillus pallidus on bioprocessing of beet vinasse derived from ethanol industries.

This work aimed to evaluate the applicability of Aeribacillus pallidus for the aerobic treatment of the concentrated beet vinasse with high chemical oxygen demand (COD 685 g.L-1) that is defined as an environmental pollutant. This bacterium is a polyextremophilic strain and grow aerobically up to 7.5% vinasse at high temperature (50 °C). In the bioreactor and under controlled conditions, A. pallidus reduced the soluble COD content of 5% vinasse up to 27% during 48 h and utilized glucose and glycerol, completely. Furthermore, a reduction of manganese, copper, aluminum, and nickel concentrations was observed in the treated vinasse with A. pallidus. The obtained results make this strain as an appropriate alternative to be used for the aerobic bioprocessing of the vinasse.

Emerging applications of biochar: Improving pig manure composting and attenuation of heavy metal mobility in mature compost.

This study evaluated the effect of integrated bacterial culture and biochar on heavy metal (HM) stabilization and microbial activity during pig manure composting. High-throughput sequencing was carried out on six treatments, namely T1-T6, where T2 was single application of bacteria culture (C), T3 and T5 were supplemented with 12 % wood (WB) and wheat-straw biochar (WSB), respectively, and T4 and T6 had a combination of bacterial consortium mixed with biochar (12 % WB and 12 % WSB, respectively). T1 was used as control for the comparison. The results show that the populations of bacterial phyla were significantly greater in T6 and T4. The predominate phylum were Proteobacteria (56.22 %), Bacteroidetes (35.40 %), and Firmicutes (8.38 %), and the dominant genera were Marinimicrobium (53.14 %), Moheibacter (35.22 %), and Erysipelothrix (5.02 %). Additionally, the correlation analysis revealed the significance of T6, as the interaction of biochar and bacterial culture influenced the HM adsorption efficiency and microbial dynamics during composting. Overall, the integrated bacterial culture and biochar application promoted the immobilization of HMs (Cu and Zn) owing to improved adsorption, and enhanced the abundance and selectivity of the bacterial community to promote degradation and improving the safety and quality of the final compost product.

Characterization of Nizimuddinia zanardini macroalgae biomass composition and its potential for biofuel production.

Nizimuddinia zanardini macroalgae, harvested from Persian Gulf, was chemically characterized and employed for the production of ethanol, seaweed extract, alginic acid, and biogas. In order to improve the products yields, the biomass was pretreated with dilute sulfuric acid and hot water. The pretreated and untreated biomasses were subjected to enzymatic hydrolysis by cellulase (15FPU/g) and ß-glucosidase (30IU/g). Hydrolysis yield of glucan was 29.8, 82.5, and 72.7g/kg for the untreated, hot-water pretreated, and acid pretreated biomass, respectively. Anaerobic fermentation of hydrolysates by Saccharomycescerevisiae resulted in the maximum ethanol yield of 34.6g/kg of the dried biomass. A seaweed extract containing mannitol and a solid residue containing alginic acid were recovered as the main byproducts of the ethanol production. On the other hand, the biogas yield from the biomass was increased from 170 to 200m(3) per ton of dried algae biomass by hot water pretreatment.

Effect of fungal and phosphoric acid pretreatment on ethanol production from oil palm empty fruit bunches (OPEFB).

Oil palm empty fruit bunches (OPEFB), a lignocellulosic residue of palm oil industries was examined for ethanol production. Milled OPEFB exposed to simultaneous saccharification and fermentation (SSF) with enzymes and Saccharomyces cerevisiae resulted just in 14.5% ethanol yield compared to the theoretical yield. Therefore, chemical pretreatment with phosphoric acid, a biological pretreatment with white-rot fungus Pleurotus floridanus, and their combination were carried out on OPEFB prior to the SSF. Pretreatment with phosphoric acid, combination of both methods and just fungal pretreatment improved the digestibility of OPEFB by 24.0, 16.5 and 4.5 times, respectively. During the SSF, phosphoric acid pretreatment, combination of fungal and phosphoric acid pretreatment and just fungal pretreatment resulted in the highest 89.4%, 62.8% and 27.9% of the theoretical ethanol yield, respectively. However, the recovery of the OPEFB after the fungal pretreatment was 98.7%, which was higher than after phosphoric acid pretreatment (36.5%) and combined pretreatment (45.2%).

Structural changes of oil palm empty fruit bunch (OPEFB) after fungal and phosphoric acid pretreatment.

Oil palm empty fruit bunch (OPEFB) was pretreated using white-rot fungus Pleurotus floridanus, phosphoric acid or their combination, and the results were evaluated based on the biomass components, and its structural and morphological changes. The carbohydrate losses after fungal, phosphoric acid, and fungal followed by phosphoric acid pretreatments were 7.89%, 35.65%, and 33.77%, respectively. The pretreatments changed the hydrogen bonds of cellulose and linkages between lignin and carbohydrate, which is associated with crystallinity of cellulose of OPEFB. Lateral Order Index (LOI) of OPEFB with no pretreatment, with fungal, phosphoric acid, and fungal followed by phosphoric acid pretreatments were 2.77, 1.42, 0.67, and 0.60, respectively. Phosphoric acid pretreatment showed morphological changes of OPEFB, indicated by the damage of fibre structure into smaller particle size. The fungal-, phosphoric acid-, and fungal followed by phosphoric acid pretreatments have improved the digestibility of OPEFB's cellulose by 4, 6.3, and 7.4 folds, respectively.

Production of biofuels, limonene and pectin from citrus wastes.

Production of ethanol, biogas, pectin and limonene from citrus wastes (CWs) by an integrated process was investigated. CWs were hydrolyzed by dilute-acid process in a pilot plant reactor equipped with an explosive drainage. Hydrolysis variables including temperature and residence time were optimized by applying a central composite rotatable experimental design (CCRD). The best sugar yield (0.41g/g of the total dry CWs) was obtained by dilute-acid hydrolysis at 150 degrees C and 6min residence time. At this condition, high solubilization of pectin present in the CWs was obtained, and 77.6% of total pectin content of CWs could be recovered by solvent recovery. Degree of esterification and ash content of produced pectin were 63.7% and 4.23%, respectively. In addition, the limonene of the CWs was effectively removed through flashing of the hydrolyzates into an expansion tank. The sugars present in the hydrolyzates were converted to ethanol using baker's yeast, while an ethanol yield of 0.43g/g of the fermentable sugars was obtained. Then, the stillage and the remaining solid materials of the hydrolyzed CWs were anaerobically digested to obtain biogas. In summary, one ton of CWs with 20% dry weight resulted in 39.64l ethanol, 45m(3) methane, 8.9l limonene, and 38.8kg pectin.

Continuous fermentation of wheat-supplemented lignocellulose hydrolysate with different types of cell retention.

Medium supplementation and process alternatives for fuel ethanol production from dilute acid lignocellulose hydrolysate were investigated. Dilute acid lignocellulose hydrolysate supplemented with enzymatically hydrolysed wheat flour could sustain continuous anaerobic cultivation of Saccharomyces cerevisiae ATCC 96581 if further supplemented with ammonium sulphate and biotin. This medium composition allowed for a hexose utilisation of 73% and an ethanol production of 36 mmol l(-1) h(-1) in chemostat cultivation at dilution rate 0.10 h(-1). Three different methods for cell retention were compared for improved fermentation of supplemented lignocellulose hydrolysate: cell recirculation by filtration, cell recirculation by sedimentation and cell immobilisation in calcium alginate. All three cell retention methods improved the hexose conversion and increased the volumetric ethanol production rate. Recirculation of 75% of the bioreactor outlet flow by filtration improved the hexose utilisation from 76% to 94%. Sedimentation turned out to be an efficient method for cell separation; the cell concentration in the reactor was 32 times higher than in the outflow after 60 h of substrate feeding. However, chemostat and continuous cell recirculation cultures became severely inhibited when the dilution rate was increased to 0.20 h(-1). In contrast, an immobilised system kept producing ethanol at a stable level also at dilution rate 0.30 h(-1).

Production of mycelium biomass and ethanol from paper pulp sulfite liquor by Rhizopus oryzae.

The cultivation conditions for Rhizopus oryzae grown in synthetic medium and paper pulp spent sulfite liquor (SSL) were investigated to achieve high biomass and ethanol yields using shake flasks and bioreactors. The fungus assimilated the hexoses glucose, mannose and galactose, and the pentoses xylose and arabinose as well as acetic acid which are present in SSL. The assimilation of hexoses was faster than pentoses during cultivation in a synthetic medium. However, all sugars were assimilated concomitantly during growth in SSL supplemented with ammonium, magnesium, calcium, phosphate, sulfate and trace amounts of some other metal ions (SSL-S). The medium composition had an important influence on biomass yield. The highest biomass yields, viz. 0.18 and 0.43 g biomass/g sugar were obtained, when the cells were cultivated in shake flasks with a synthetic medium containing glucose as carbon and energy source and SSL-S, respectively. The corresponding yields in a bioreactor with more efficient aeration were 0.22 and 0.55 g/g. In addition to the biomass, ethanol, lactic acid, and glycerol were important extracellular metabolites of the cultivation with maximum yields of 0.37, 0.30 and 0.09 g/g, respectively. When the source of sugars in the medium was exhausted, the fungus consumed the metabolites produced, such that the liquid medium was depleted of potential oxidizable nutrients. In general, there was a direct competition between lactic acid and ethanol among the metabolites. Poor medium compositions and cultivation conditions resulted in higher yields of lactic acid, whereas the ethanol and biomass yields were higher in rich media. SSL-S supported good growth of mycelium and a high ethanol yield.