Mid Sweden University

The pulp and paper industry in Sweden annually produce millions of tons of side-stream materials as black liquor, pulp and paper mill sludge, sulfite liquor and lignosulfonate. These lignocellulosic based materials can be more utilized today in biorefinery processes with microorganisms to produce high-value products as lipids, proteins and biofuels. In this work, we used five side-stream materials as carbon source in fermentation with two oleaginous yeasts, Lipomyces starkeyi and Rhodotorula toruloides. We analyzed lipid production, fatty acid profiles, inhibitors, phenolics, free sugars and metals before and after batch fermentation in 2 L bioreactors. Steam-exploded hardwood media was used as reference as it's known to be a good substrate for the oleaginous yeast species and after fermentation the lipid yield for R. toruloides was 17 % (w/w) and for L. starkeyi 13 % (w/w). The side-stream materials contained less than 30 % of free sugar compared to the reference media and the total lipid yield was thus less than 2.7 %, (w/w). R. toruloides utilized various sugars during fermentation and L. starkeyi mostly consumed glucose and xylose. Both yeast species also showed a possible ability to utilize various phenolics indicating their metabolic potential to convert depolymerized lignin along with wood-based sugars to lipids and proteins.

Decentralized composting is an emerging method for managing biowaste, engaging waste generators as active recyclers in the waste management cycle. Evaluating performance and identifying optimization opportunities within this composting framework is essential to maximize its benefits and address its challenges. In small-scale composters, fresh waste is continuously mixed with previously added materials, shifting the typical composting process. As with larger systems, the composition of the feedstock influences the temperature profile and the quality of the final product. The issue of whether to include animal-source waste remains controversial in the development of standards and program guidelines. On the other hand, evaluating a leachate recycling method could help prevent nutrient loss and mitigate environmental impacts when bulking agents are lacking. In this study, kitchen and garden wastes were composted in 500-L static composters under cold climate conditions. We examined obtained compost stability, maturity, and quality parameters to determine the effects of adding animal by-product waste and/or recycling leachate. Our findings indicate that including animal by-products allows reaching sanitation temperatures under cold weather conditions and that recycling leachates could reduce nutrient losses and alleviate environmental and other user concerns while improving temperature, stability, maturity, and product quality patterns in decentralized composting. 

Fiberbanks refer to a type of fibrous sediment originated by the forestry and wood pulping industry in Sweden. These anthropogenic sediments are significantly contaminated with potentially toxic elements, and a diverse array of organic pollutants. Additionally, these sediments are of environmental concern due to their potential role in greenhouse gas emissions. Given the environmental risks posed by these sediments, the development of effective remediation strategies is of critical importance. However, no specialized methods have been established yet for the cleanup of this specific type of contaminated sediments. To identify effective fungal species for the mycoremediation of the fiberbank substrate, we performed a detailed screening experiment. In this research, we primarily aimed at assessing both the growth capacity and the proficiency in degrading organic pollutants of 26 native white-rot fungi (WRF) species. These species were sourced from natural forest environments in northern Sweden. The experimental setup involved evaluating the WRF on plates containing fiberbank material with a central Hagem-agar disc to closely monitor the interaction of these species with fiberbank substrates. Among the fungi tested, Laetiporus sulphureus exhibited the highest growth area percentage at 72%, followed by Hymenochaete tabacina at 68% and Diplomitoporus crustulinus at 67%. For the removal of 2–3 ring polycyclic aromatic hydrocarbons (PAHs), Phellinus punctatus led with 68%, with Cystostereum muraii at 57% and Diplomitoporus crustulinus at 49%. Regarding the removal percentage of 4–6 ring PAHs, Diplomitoporus crustulinus showed the highest efficiency at 44%, followed by Phlebia tremellosa at 40% and Phlebiopsis gigantea at 28%. 

The syngas produced from biomass gasification is a great potential energy resource, which can well be utilized to produce biomass-based substitute natural gas (BioSNG) via syngas biomethanation. CO biomethanation is one of the key issues in the biomethanation process and was studied experimentally in this work with respect to the effect of anaerobic granular sludge semi-disaggregation. The results show 1.07 times higher averaged CH4 production rate with the semi-disaggregated granular sludge than the whole granular sludge at 35 °C, and 1.69 times higher at 55 °C. The main mechanisms behind the enhanced CH4 production rate, especially under the thermophilic condition, are the improvement of microbial interspecific syntrophic association caused by the higher electron and substrate transfer rate, and more active cell growth and metabolism as reflected in higher abundance of functional genes and enzymes and less useless extracellular polymeric substances. The CO biomethanation enhancement occurs in the conversion of the substrate to the intermediate products. The semi-disaggregation of anaerobic granular sludge or similar way to strengthen interspecific association is an effective approach to improve the ability and tolerance of microbial cultures under the CO atmosphere. This technique can well be applied for the energy conversion from the CO-rich gas substrates into BioSNG via CO biomethanation under the thermophilic condition, or for the production of intermediates as fuels/chemicals under the mesophilic condition. 

The pine sawfly Diprion jingyuanensis Xiao and Zhang (Hymenoptera: Diprionidae) is a serious pest of Pinus tabulaeformis Carr. in the Shanxi, Gansu, and Inner Mongolia provinces in P. R. China. The sex pheromone of D. jingyuanensis was shown to be the propionate ester of 3,7-dimethyl-2-tridecanol. Virgin females contained an approximate 1:3 blend of the pheromone precursors erythro-(2S,3S,7R/S and 2R,3R,7R/S)-3,7-dimethyl-2-tridecanol and threo-(2S,3R,7R/S and 2R,3S,7R/S)-3,7-dimethyl-2-tridecanol, but the exact stereoisomers were not determined. Males responded the strongest to the propionate ester of the two threo-isomers, (2S,3R,7R) and (2S,3R,7S), in electroantennogram (EAG) recordings, followed by a significant EAG response to the (2S,3R,7R) propionate of diprionol (pheromone component of D. similis), whereas the remaining two isomers (2S,3S,7S and 2S,3S,7R) of the propionate ester of 3,7-dimethyl-2-tridecanol and the acetate of the (2S,3R,7R) isomer (one of the two pheromone components of D. pini) did not elicit any significant increase in antennal response. In the field, the strongly EAG-active (2S,3R,7R)-isomer alone was only weakly (but significantly) attractive to D. jingyuanensis males at 100 µg, while the equally EAG- active (2S,3R,7S)-isomer alone at the same loading was 8–14 times more attractive than was the (2S,3R,7R)-isomer alone. Traps baited with the same amounts of the two threo-isomers ((2S,3R,7R) and (2S,3R,7S), 100 µg + 100 µg) caught significantly more males than did traps baited with other isomers, either of the two isomers alone or other proportions of the two isomers. Thus, the (2S,3R,7S)-isomer is considered as a strong and essential sex-attractant component for D. jingyuanensis males, whereas the (2S,3R,7R)-isomer is a weak but synergistic sex-attractant. This is one of the few examples of a pine sawfly responding significantly stronger to a binary blend of stereoisomers in a synergistic fashion than to a single stereoisomer alone. 

In order to utilize a wider range of low-grade syngas, the syngas biomethanation was studied in this work with respect to the gas–liquid mass transfer and the reactor start-up strategy. Two reactors, a continuous stirred tank (CSTR) and a bubble column with gas recirculation (BCR-C), were used in the experiment by feeding an artificial syngas of 20% H2, 50% CO, and 30% CO2 into the reactors at 55 °C. The results showed that the CH4 productivity was slightly increased by reducing the gas retention time (GRT), but was significantly improved by increasing the stirring speed in the CSTR and the gas circulation rate in the BCR-C. The best syngas biomethanation performance of the CSTR with a CH4 productivity of 22.20 mmol·Lr−1·day−1 and a yield of 49.01% was achieved at a GRT of 0.833 h and a stirring speed of 300 rpm, while for the BCR-C, the best performance with a CH4 productivity of 61.96 mmol·Lr−1·day−1 and a yield of 87.57% was achieved at a GRT of 0.625 h and a gas circulation rate of 40 L·Lr−1·h−1. The gas–liquid mass transfer capability provided by gas circulation is far superior to mechanical stirring, leading to a much better performance of low-grade syngas biomethanation in the BCR-C. Feeding H2/CO2 during the startup stage of the reactor can effectively stimulate the growth and metabolism of microorganisms, and create a better metabolic environment for subsequent low-grade syngas biomethanation. In addition, during the thermophilic biomethanation of syngas, Methanothermobacter is the dominant genus. 

Lignocellulose-bearing sediments are legacies of the previously unregulated wastewater discharge from the pulp and paper industry, causing large quantities of toxic organic waste on the Baltic Sea floor and on the bottom of rivers and lakes. Several km2 are covered with deposits of lignocellulosic residues, typically heavily contaminated with complex mixtures of organic and inorganic pollutants, posing a serious threat to human and ecological health. The high toxicity and the large volume of the polluted material are challenges for remediation endeavours. The lignocellulosic material is also a considerable bioresource with a high energy density, and due to its quantity, it could appeal to commercialization as feedstock for various marketable goods. This study sets out to explore the potential of using this polluted material as a resource for industrial production at the same time as it is detoxified. Information about modern production methods for lignocellulosic material that can be adapted to a polluted feedstock is reviewed. Biochemical methods such as composting, anaerobic digestion, as well as, thermochemical methods, for instance, HTC, HTL, pyrolysis, gasification and torrefaction have been assessed. Potential products from lignocellulose-bearing sediment material include biochar, liquid and gaseous biofuels, growing substrate. The use of a contaminated feedstock may make the process more expensive, but the suggested methods should be seen as an alternative to remediation methods that only involve costs. Several experiments were highlighted that support the conception that combined remediation and generation of marketable goods may be an appropriate way to address polluted lignocellulose-bearing sediments. Graphic abstract: [Figure not available: see fulltext.] 

Polygraphus proximus, a four-eyed fir bark beetle, is an invasive bark beetle species which has caused extensive damage to forests of Abies sibirica in southern and western Siberia and to Abies species in the European part of Russia. There is a high risk that the pest insect will spread to areas where it is currently not considered present, such as the European Union. In these areas, it threatens to attack conifer forests of various species which may result in major environmental and economic impact. The aim of this study was to identify pheromone components of P. proximus that can be used as pheromone baits. Males and females of P. proximus were allowed to bore into the bark of stem sections of Abies sibirica at the laboratory, and volatiles were collected with solid-phase microextraction (SPME). Analyses of these extracts with gas chromatography-mass spectrometry (GC–MS) revealed several sex-specific compounds. In total, twelve male-specific compounds and one female-specific compound were identified. The major male-specific compound determined by GC peak area was (Z)‐2‐(3,3‐dimethylcyclohexylidene)‐ethanol [(Z)-DMCHE] and the minor male-specific compounds were 3-methyl-3-buten-1-ol, 3-methyl-2-buten-1-ol, 3-methyl-2-butenal, benzyl alcohol, fragranol, 7-methyl-3-methylene-6-octen-1-ol, (Z)- and (E)-2-(3,3-dimethylcyclohexylidene)-acetaldehyde, geraniol, geranial and papayanol. The only female-specific compound was identified as 1-hexanol. Two of the male-specific compounds, (Z)‐DMCHE and 3-methyl-2-buten-1-ol were shown to attract males and females of P. proximus in field studies. Thus, we now for the first time can present the structures of two male-specific components that are biologically active parts of P. proximus aggregation pheromone. However, some chemical communication overlap between P. proximus and P. subopacus needs to be further investigated as (Z)‐DMCHE also attracted males and females of P. subopacus. 

All living things speak chemistry. The challenge is to reveal the vocabulary, the odorants that enable communication across phylogenies and to translate them to physiological, behavioral, and ecological function. Olfactory receptors (ORs) interface animals with airborne odorants. Expression in heterologous cells makes it possible to interrogate single ORs and to identify cognate ligands. The cosmopolitan, anthropophilic strain of the vinegar fly Drosophila melanogaster depends on human resources and housing for survival. Curiously, humans sense the pheromone (Z)-4-undecenal (Z4-11Al) released by single fly females. A screening of all human ORs shows that the most highly expressed OR10A6 is tuned to Z4-11Al. Females of an ancestral African fly strain release a blend of Z4-11Al and Z4-9Al that produces a different aroma, which is how we distinguish these fly strains by nose. That flies and humans sense Z4-11Al via dedicated ORs shows how convergent evolution shapes communication channels between vertebrate and invertebrate animals. 

Extracts of Diprion similis females contained about 15 ng of the sex pheromone precursor 3,7‐dimethylpentadecan‐2‐ol per female. After derivatisation with (S)‐2‐acetoxypropanoyl chloride, we found that the major stereoisomer in the extract was (2S,3R,7R)‐3,7‐dimethylpentadecan‐2‐ol. Small amounts of other stereoisomers of 3,7‐dimethylpentadecan‐2‐ol were also identified in the extract, namely 1% of (2R,3S,7S), 0.3% (2R,3R,7R) and 0.4% of (2R,3R,7S). An unknown fifth substance showed a very similar spectrum to 3,7‐dimethylpentadecan‐2‐ol, both in SIM and full scan mode. None of the earlier suggested behavioural synergistic isomers ((2S,3S,7S), (2S,3S,7R) and (2S,3R,7S)) were detected in the extracts. In field tests in Ontario, Canada, the earlier identified main pheromone component, viz. the propanoate of (2S,3R,7R)‐3,7‐dimethylpentadecan‐2‐ol, was tested alone and in combination with other stereoisomers, earlier reported to be synergistic. No synergistic effects were detected and the threo four‐isomer blend was as attractive as the pure main compound. Thus, one of the few examples of a diprionid sawfly using more than one substance in its sex pheromone could not be confirmed. The results also suggest that monitoring programs can use the more easily synthesized threo‐blend without losing efficiency. Furthermore, the study suggests that other diprionid pheromones may benefit from a reinvestigation, to clarify possible synergistic effects of stereoisomers.