The discovery of the growth promoting property of antibiotics led to their use as antibiotic feed additives (AFAs) in animal feed at sub-therapeutic doses. Although this has been beneficial for ...animal health and productivity, it has been, essentially, a double-edged sword. The continued and non-judicious use of AFAs has led to the selection and dissemination of antibiotic-resistant strains of poultry pathogens such as Salmonella, Campylobacter and Escherichia coli. The rapid spread of drug-resistant pathogens as well as emergence of antibiotic-related environmental pollutants is of global concern. Hence, the identification and development of new and effective alternatives to antibiotics that do not hinder productivity is imperative. For this, it is essential to understand not only the molecular basis of development of resistance to AFAs but also the mechanisms of action of AFA alternatives and how they differ from AFAs. This review provides a molecular perspective on the alternatives to antibiotics that have been proposed till date and their current trends, as well as novel approaches such as development of improved delivery systems.
Full text
Available for:
BFBNIB, DOBA, GIS, IJS, IZUM, KILJ, KISLJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Mass transfer and kinetic limitations are two obstacles to the removal of a pollutant from the gas phase in a biofilter (BF) or a biotrickling filter (BTF). The issue becomes more challenging when ...mass transfer and kinetic limitations are present especially for treatment of pollutants in mixtures. In the present study, the most common organic pollutants which may have mass transfer or kinetic limitations in BFs and BTFs are described. Accordingly, the recent studies of mass transfer limited and kinetic limited organic pollutants elimination in BFs and BTFs are reviewed. Subsequently, the most effective operating parameters for each sort of limitations are discussed. Finally, some improved bioprocesses like two liquid phase biotrickling filters, step feeding and hybrid biofilters to overcome the limitations of mass transfer and kinetic limited organic pollutants are discussed.
•Mass transfer and kinetic limitations are two main limitations in biofiltration.•Pollutants were categorized in 2 groups as mass transfer and kinetic limited.•Parameters for the elimination of the 2 groups in biofilters were reviewed.•Biofiltration of the two groups in a mixture were investigated.•Improved biofilter's configurations to enhance the limitations were discussed.
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
Display omitted
•A total furfural degradation of 3 g/L was observed by R. toruloides-1588.•R. toruloides-1588 degraded furfural into furfuryl alcohol and 2-furoic acid.•R. toruloides-1588 accumulated ...52% w/w of lipids in the presence of 1 g/L of furfural.•R. toruloides-1588 degraded 2 g/L of furfural in absence of glucose as a carbon source.
The presence of furfural in the hydrolysates obtained from lignocellulosic biomass sources represents an enormous challenge during their fermentation because furfural is a toxic compound for different microorganisms. Rhodosporidium toruloides-1588 can grow and accumulate lipids using wood hydrolysate as a substrate containing up to 1 g/L of furfural. In this study, the capacity of R. toruloides-1588 to grow and accumulate lipids using furfural without glucose in the media has been observed. R. toruloides-1588 degraded up to 3 g/L of furfural into furfuryl alcohol (1.8 g/L) and 2-furoic acid (0.9 g/L). Furthermore, R. toruloides-1588 accumulated 52% and 30% of its dry weight into lipids using YM media and YM media without glucose, respectively. Fatty acids such as palmitic, stearic and oleic were the most abundant. Finally, R. toruloides-1588 could potentially utilize furfural as a carbon source.
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
The interest in microbial lipids has recently increased because of their wide use to produce several value-added compounds in the biofuel, pharmaceutical and food industries. Oleaginous yeast such as ...Rhodosporidium toruloides could be an efficient option because of its ability to consume five-carbon sugars, high lipid accumulation, and tolerance to toxic compounds such as furans, phenolic compounds, and organic acids. The present study aims to investigate the effect of different initial sugar ratios, in combination with different carbon/nitrogen ratios, and the use of dibasic sodium phosphate (Na2HPO4) as an inducer on cell biomass production, sugar consumption, and lipid accumulation by Rhodosporidium toruloides-1588. The investigation showed a maximum lipid accumulation of 5.35 gL-1 (0.28 g of lipids/g of sugar) under the culture conditions of initial glucose: xylose ratio of 1:1, C/N ratio of 70, and Na2HPO4 concentration of 1.05 gL-1. The predominant lipids composition was palmitic, stearic, oleic, and linoleic acids which could be used as a suitable feedstock for biofuel production. Additionally, under the optimal conditions (initial glucose: xylose ratio of 1:1, 1.19 gL-1 of Na2HPO4 and C/N ratio of 70.50) an increase of 10.5% and 7.5% in lipid accumulation was observed, compared with control treatments (glucose and xylose, respectively). In addition, the study shows the ability of R. toruloides-1588 to tolerate inhibitors, a feature that could be a promising alternative to increase the feasibility of the microbial lipid production process using undetoxified wood hydrolysate as a sustainable culture media.
Display omitted
•Under optimal conditions, the strain accumulated 40% of its dry weight into lipids.•The strain consumed up to 60% in the optimal culture conditions.•A carbon/nitrogen ratio of 70 shows the most promising results for lipid accumulation.•A 90% of furfural was degraded.•Renewable feedstock from forestry residues is a suitable substrate to produce microbial lipids.
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Rhodosporidium toruloides is an oleaginous yeast that can accumulate up to 70% of its dry biomass as lipids and can use C5 and C6 sugars as a carbon source, that are present in hydrolysates from ...different lignocellulosic biomass. R. toruloides can be an alternative for the valorization of forestry residues and the obtention of higher value-added products. In this study, five strains of R. toruloides were evaluated to find the most efficient yeast strain for C5 and C6 sugars utilization, using lignocellulosic hydrolysates as a culture media. Sugar consumption was similar between all strains. Nevertheless, it was different among C6 and C5 hydrolysates, with maximum sugar utilization of 98%, and 60% for C6 and C5 hydrolysate, respectively. Among the studied strains, the highest lipid production was observed in R. toruloides-1588 with 23.33 g of lipids/L in C6 hydrolysate after 112 h. Whereas, highest lipid production in C5 hydrolysate was observed in R. toruloides-7191 with 14.67 g of lipids/L after 120 h. Predominantly, fatty acids for R. toruloides-1588 was oleic, palmitic, and stearic acids and pentadecanoic, palmitic, and heptadecanoic acids for R. toruloides-7191. Moreover, both strains grew and produced lipids in the presence of inhibitor compounds, such as levulinic acid (13.88 mgL−1), 5-HMF (80.86 mgL−1), furfural (153.54 mgL−1), vanillin (17.17 mgL−1), vanillic acid (85.25 mgL−1), syringaldehyde (41.83 mgL−1), ferulic acid (1.66 mgL−1), and 4-hydroxybenzoic acid (0.85 mgL−1). The study revealed that R. toruloides-1588 and R. toruloides-7191 are promising strains for C5 and C6 sugar utilization from lignocellulosic hydrolysates for lipid production.
•Undetoxified lignocellulosic wood hydrolysate was used as culture media.•C5 and C6 sugar utilization present in lignocellulosic biomass hydrolysate by Rhodosporidium toruloides.•Rhodosporidium toruloides is a promising yeast to produce large quantities of lipids from lignocellulosic wood hydrolysate.•Inhibitors had no effect on lipid production in R. toruloides.
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
•High nitrate concentration (1600ppm) was achieved after 28 days of Nitrobacter sp. growing in a synthetic media which is enough for growing plants.•Co-culture of Nitrosomonas sp., Nitrobacter sp. ...and compost microorganisms to nitrify vegetable waste is feasible opening the way to valorize organic wastes.•Nitrite toxicity is observed (after ten days) when the media contains Nitrosomonas sp., indicating that the use of this microorganism must be optimized to avoid damaging vegetable cultures.
Current inorganic chemical-based fertilizers for soils have adverse impacts on human health and environment. In the present work, two nitrifying bacteria, i.e. Nitrosomonas sp. DSM 28437 and Nitrobacter sp. DSM 10236, were explored for the production of nitrate in vegetable wastes. For this purpose, the nitrite production by Nitrosomonas sp. and nitrate production by Nitrobacter sp. in two synthetic media containing ammonium and nitrite, respectively were investigated. Also, simultaneous growth of both bacteria in a single synthetic medium containing ammonium was investigated. Finally, the performance of both bacteria in a mixture of vegetable wastes, where a consortia of microorganisms present in cattle-based compost produced ammonium, were investigated. Highest concentration of nitrite (13.2ppm) and nitrate (1600ppm) in Nitrosomonas sp. and Nitrobacter sp. inoculated synthetic media were achieved after 12 and 28days, respectively. The simultaneous growth of both bacteria in synthetic media and both bacteria along with compost microorganisms in vegetable wastes resulted in 12 and 20ppm nitrate, respectively. Also, it was observed that with increasing time, the optical density of Nitrobacter sp. population increased from 0.04 to 0.72 after 35days, but for Nitrosomonas sp., until 12days, the optical density increased 0.3 from to 0.6 and then decreased to 0.2 on day 21 because of nitrite toxicity to the microorganism. The transformation of ammonium to nitrate using Nitrosomonas sp. and Nitrobacter sp. in synthetic media and a mixture of vegetable wastes was studied to develop a new organic fertilizer containing nitrogen source.
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
Whey is a dairy residue generated during the production of cheese and yogurt. Whey contains mainly lactose and proteins, contributing to its high chemical oxygen demand (COD). Current environmental ...regulations request proper whey disposal to avoid environmental pollution. Whey components can be transformed by yeast into ethanol and biomolecules with aroma and flavor properties, for example, 2-phenyethanol (2PE), highly appreciated in the industry due to its organoleptic and biocidal properties. The present study aimed to valorize agri-food residues in 2PE by developing suitable bioprocess. Cheese whey was used as substrate source, whereas crab headshells, residual soy cake, and brewer's spent yeast (BSY) were used as renewable nitrogen sources for the yeasts
and
. The BSYs promoted the growth of both yeasts and the production of 2PE in flask fermentation. The bioprocess scale-up to 2 L bioreactor allowed for obtaining a 2PE productivity of 0.04 g
/L·h, twofold better productivity results compared to the literature. The bioprocess can save a treatment unit because the whey COD decreased under the detection limit of the analytical method, which is lower than environmental requirements. In this way, the bioprocess prevents environmental contamination and contributes to the circular economy of the dairy industry.
Full text
Available for:
IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
•Polyimide aerogels were obtained with an efficient environmental-friendly method.•Polyimide aerogels can be used as support materials for enzyme immobilization.•The resulted carbamazepine removal ...efficiency is high.
Since it is known that conventional wastewater treatment plants cannot completely remove pharmaceutical compounds, such as carbamazepine, the need for their removal has intensified. The use of biocatalysts, such as enzyme is an environmentally friendly method for carbamazepine biodegradation. Nevertheless, enzyme immobilization is required to facilitate the recovery and reusability and avoid the loss of enzyme. In this work, laccase was immobilized on modified polyimide aerogels by means of covalent bonding. Results showed that the immobilized laccase on polyimide aerogels possesses significantly improved activity under acidic or basic pH range in comparison with the free enzyme. Furthermore, for all the temperature range the activity of the immobilized enzyme was higher compared to the free enzyme form. The storage stability improved by the immobilization on this support material. The reusability tests towards oxidation of 2, 2′-azino-bis (3-ethylbenzothiazoline-6-sulphonicacid) (ABTS) showed that the immobilized laccase maintained 22% of the initial activity after 7 cycles. Immobilized laccase on polyimide aerogels for carbamazepine (CBZ) degradation exhibited 76% and 74% removal in spiked water and secondary effluent, respectively. Furthermore, after 7 cycles the CBZ removal efficiency remained higher (50% and 65% for spiked water and secondary effluent, respectively).
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
PDF
