Lignin valorization for fuels and value-added products is essential to enhance the profitability and sustainability of biorefineries. Due to the complex and heterogeneous structure of lignin, technical barriers hinder the implementation of economic lignin utilization. Here, we summarize the major challenges facing lignin valorization processes. Different pretreatment methods, especially emerging combinatorial pretreatment approaches for isolating and tailoring lignin are introduced. To overcome the heterogeneity of lignin structure and improve lignin processability, advances in fractionation approaches including organosolv extraction, membrane technology, and gradient precipitation are analyzed and presented. Furthermore, progress in lignin valorization by thermochemical and biological conversion coupling with pretreatment and fractionation are systematically reviewed. Finally, we discuss advanced strategies and perspectives for future research involving biomass pretreatment, lignin fractionation and conversion processes.
Biomass ; Lignin

Aims: In solid state fermentation (SSF), estimation of biomass is difficult as fungal mycelium penetrates deep and remains attached to the solid substrate particles. This study examines and evaluates a new technique based on colour changes of fermented substrates during SSF as an indicator for fungal growth. Methodology and Results: SSF refers to microbial fermentation, which takes place in the absence or near absence of free water, thus being close to the natural environment in which the selected microorganisms, especially fungi, are naturally adapted. Although many promising methods are available, the evaluation of microbial growth in SSF may sometimes become difficult, impractical, and inaccurate. Essentially, this remains another critical issue for monitoring growth. In this study, measurements of colour changes of fermented substrates during SSF are used as indicators for growth and this technique has a potential to be used to quantify growth of microbes. For the growth of Aspergillus awamori and A. oryzae on wheat bran, soybean hulls, and rapeseed meal, it was confirmed that colour changes were directly proportional to the fungal growth. This new approach is an important complementation to the existing techniques, especially for basic studies. The advantages of this method are its ease of use, fast, non-destructive, cheap, and requires no special and expensive reagents. The key finding is that the colorimetric technique demonstrated in this study provides good means to estimate growth than that obtained by visual observation or spores counting.
Biomass ; Fermentation

Biomass is the most abundant organic macromolecules in nature, which is expected to achieve the brilliant of biorefinery equivalent to petroleum refining. However, it is considered as the future industry to human due to the complicated composition and transformation processes. The traditional lignocellulose bio-refining thoughts ignored the functional requirements of products, but spent a lot of energies to destruct macromolecule into small molecules, and then converted the small molecules into different products, which was high energy consumption and low atom economy. How to realize the biorefinery of lignocellulose is the key point and difficulty to achieve the biomass industry. An ideal biorefinery of lignocellulose should as far as possibly to obtain the maximum yield of each component, to maintain the integrity of the molecule, to optimize the utilization of raw materials and finally to realize the maximum value. Therefore, it requires the raw materials refining of lignocellosic biomass should be based on the relationship of structure, process transformation and related product characteristics. This special issue reports the latest advances in the fields of raw material refinery, refining technologies, conversion technologies of component.
Biomass ; Biotransformation ; Lignin ; chemistry

Micro- and mini-bioreactors are characterized by their miniature working volume and comprehensive monitoring of process data, e.g., biomass, pH, dissolved oxygen, and fluorescence that are on par with conventional bench-top systems. The technical advancements of micro- and mini-bioreactors are supported by single-use material and micro-manufacturing, non-invasive optical sensors, automation such as industrial robotics and the integration of design of experiment software with data acquisition and process control. Owing to the miniature scales, micro-bioreactors typically feature lower turbulence intensity and energy dissipation rate, resulting in different mass transfer, mixing and shear conditions as compared to industrial scale equipment. Mini-bioreactors, nevertheless, are closer to large vessels. Micro- and mini-bioreactors are used mostly in screening and process development nowadays, owing to their combined high throughput and richness of data. They are also the hardware that will enable "precision medicine" in the near future.
Biomass ; Bioreactors ; Oxygen

With the rapid development of modern biotechnology, fermentation process is increasingly important in industrial production. To guarantee the stability of products, fermentation process should be elaborately monitored and controlled. Biomass is an important parameter for on-line monitoring in bioprocesses because biomass can reflect cell growth in a bioreactor directly. In-situ microscope, a non-invasive and image-analysis based technology, can real-time monitor cells in biological process. This review summarizes the development and application of in-situ microscopy in biomass monitoring.
Biomass ; Bioreactors ; Biotechnology ; Fermentation ; Microscopy

OBJECTIVETo study the biomass structure of Epimedium acuminatum Franch in the different ecological environments for the development and protection.

METHODThrough the scientific investigation in four typical habitats, the sampling spots were set up, the functional modules' biomass structure and relationship of E. acuminatum were researched.

RESULTThe average of rhizome, as the largest biomass, and the average total biomass had the same pattern: the open areas of forest edge > shrub lumber > shrub-weed > stream drains. The ratio of the functional modules' biomass had different rates under different habitat conditions. By analyzing and combining investigation, the aerial part of E. acuminatum in the shrub-weed were comparative advantage, and the roots of nutrient accumulation of E. acuminatum in the open areas of forest edge were the highest efficient. Under different ecological condition, the distribution of water metabolism was different strategies.

CONCLUSIONIn the open areas of forest edge, E. acuminatum growing well, followed by shrub-weed. These two habitats are the ideal ecological environments while the rhizome or the whole plant used as medicine, but also the protection of E. acuminatum.

A newly isolated white rot fungal strain KU-RNW027 was identified as Trametes polyzona, based on an analysis of its morphological characteristics and phylogenetic data. Aeration and fungal morphology were important factors which drove strain KU-RNW027 to secrete two different ligninolytic enzymes as manganese peroxidase (MnP) and laccase. Highest activities of MnP and laccase were obtained in a continuous shaking culture at 8 and 47 times higher, respectively, than under static conditions. Strain KU-RNW027 existed as pellets and free form mycelial clumps in submerged cultivation with the pellet form producing more enzymes. Fungal biomass increased with increasing amounts of pellet inoculum while pellet diameter decreased. Strain KU-RNW027 formed terminal chlamydospore-like structures in cultures inoculated with 0.05 g/L as optimal pellet inoculum which resulted in highest enzyme production. Enzyme production efficiency of T. polyzona KU-RNW027 depended on fungal pellet morphology as size, porosity, and formation of chlamydospore-like structures.
Biomass ; Laccase ; Manganese ; Peroxidase ; Porosity ; Trametes*

With the advantages of extensive sources, easy collection, renewability, high yield, carbon circulation, low pollution, and so on, Chinese medicinal solid waste can be converted into clean gas by pyrolysis and gasification, which is then able to serve for industrial production. This is of great practical significance in the context of energy shortage and for solid waste recycling in China. This paper reviews the research progress on biomass gasification principle, gasification medium, and reactor in gasification technology of Chinese medicinal solid waste in recent years. Meanwhile, based on the summary of related research, the defects and improvement measures regarding raw materials, gasification agents, by-products, and reactors were discussed, which provides direction for further development in the gasification technology of Chinese medicinal solid waste in the future.
Biomass ; China ; Pyrolysis ; Solid Waste ; Technology

Intense utilization and mining of fossil fuels for energy production have resulted in environmental pollution and climate change. Compared to fossil fuels, microalgae is considered as a promising candidate for biodiesel production due to its fast growth rate, high lipid content and no occupying arable land. However, monocultural microalgae bear high cost of harvesting, and are prone to contamination, making them incompetent compared with traditional renewable energy sources. Co-culture system induces self-flocculation, which may reduce the cost of microalgae harvesting and the possibility of contamination. In addition, the productivity of lipid and high-value by-products are higher in co-culture system. Therefore, co-culture system represents an economic, energy saving, and efficient technology. This review aims to highlight the advances in the co-culture system, including the mechanisms of interactions between microalgae and other microorganisms, the factors affecting the lipid production of co-culture, and the potential applications of co-culture system. Finally, the prospects and challenges to algal co-culture systems were also discussed.
Biofuels ; Biomass ; Coculture Techniques ; Flocculation ; Microalgae

Tetrapyrrole compounds are a class of compounds with important functions. They exist in living organisms and have been widely used in agriculture, food, medicine, and other fields. The cumbersome process and high cost of chemical synthesis, as well as the shortcomings of unstable quality of animal and plant extraction methods, greatly hampered the industrial production and applications of tetrapyrrole compounds. In recent years, the rapid development of synthetic biology has provided new tools for microorganisms to efficiently synthesize tetrapyrrole compounds from renewable biomass resources. This article summarizes various strategies for the biosynthesis of tetrapyrrole compounds, discusses methods to improve its biosynthesis efficiency and future prospects, with the aim to facilitate the research on biosynthesis of tetrapyrrole compounds.
Biomass ; Plants/genetics* ; Synthetic Biology ; Tetrapyrroles