Lignocellulosics in plant cell wall and their potential biological degradation

Regulation of genes encoding polysaccharide-degrading enzymes in Penicillium

Penicillium fungi, including Penicillium oxalicum, can secrete a range of efficient plant-polysaccharide-degrading enzymes (PPDEs) that is very useful for sustainable bioproduction, using renewable plant biomass as feedstock. However, the low efficiency and high cost of PPDE production seriously hamper the industrialization of processes based on PPDEs. In Penicillium, the expression of PPDE genes is strictly regulated by a complex regulatory system and molecular breeding to modify this system is a promising way to improve fungal PPDE yields. In this mini-review, we present an update on recent research progress concerning PPDE distribution and function, the regulatory mechanism of PPDE biosynthesis, and molecular breeding to produce PPDE-hyperproducing Penicillium strains. This review will facilitate future development of fungal PPDE production through metabolic engineering and synthetic biology, thereby promoting PPDE industrial biorefinery applications. KEY POINTS: • This mini review summarizes PPDE distribution and function in Penicillium. • It updates progress on the regulatory mechanism of PPDE biosynthesis in Penicillium. • It updates progress on breeding of PPDE-hyperproducing Penicillium strains.

Effect of warehouse storage on the alteration, cooking and organoleptic characteristics of Kponan yam (Dioscorea cayenensis-rotundata) of Côte d'Ivoire

Yam holds the top position in food crop production, and Kponan yam is highly prized by Ivorians. However, storage deterioration poses economic challenges for wholesalers and producers. This study assesses Kponan yam quality in warehouse storage, considering its geographical origin. To achieve this, yams from the Bondoukou, Bouna, and Kouassi-Kouassikro regions were kept at a warehouse in Abidjan, allowing an assessment of alterations, cooking properties, and organoleptic characteristics over a 3-month storage period. Kponan yam tubers were placed on boards at the warehouse's temperature (27.98 °C) and relative humidity (85.61 %). Temperature and humidity levels were recorded three times per week and four times daily at 08:00, 12:00, 16:00, and 20:00. Physical, cooking, and sensory characteristics were checked at harvest and during each month. The results showed that the main damage observed during storage at the warehouse was rotting and dehydration of the tubers. Rot rates were 47.53 % for yams grown in Bondoukou, 51.96 % for those grown in Bouna and 60.65 % for those grown in Kouassi-Kouassikro. Dehydrated tubers rates were 17.88 %, 25.04 % and 29.20 % for yams from Bondoukou, Bouna and Kouassi-Kouassikro, respectively. The browning indices of Kponan yams decrease (P < 0.05) during storage, with a much more marked effect for yams grown in Bouna (23.43-18.56) and Bondoukou (24.73-18.11), in contrast to those grown in Kouassi-Kouassikro (26.09-22.96). Hardness also dropped for Kponan yams grown in Bouna, Bondoukou and Kouassi-Kouassikro (38.94-25.19 N, 39.39-26.52 N and 35.59-26.66 N respectively). Sensory analysis showed that yams from Bouna stored for three months were rated highest in taste (score = 4). The storage quality of Kponan yams was influenced by the cultivation region. Organic production of Kponan yams benefits the environment and human health, while increasing shelf life.

Creation of Cellulolytic Communities of Soil Microorganisms-A Search for Optimal Approaches

For the targeted selection of microbial communities that provide cellulose degradation, soil samples containing cellulolytic microorganisms and specific plant residues as a substrate can be used. The details of this process have not been studied: in particular, whether the use of different soils determines the varying efficiency of communities; whether these established cellulolytic communities will have substrate specificity, and other factors. To answer these questions, four soil microbial communities with different cellulolytic activity (Podzol and the soil of Chernevaya taiga) and substrates (oat straw and hemp shives) with different levels of cellulose availability were used, followed by trained communities that were tested on botrooth substrates (in all possible combinations). Based on the analysis of the taxonomic structure of all communities and their efficiency across all substrates (decomposition level, carbon, and nitrogen content), it was shown that the most important taxa of all trained microbial cellulolytic communities are recruited from secondary soil taxa. The original soil does not affect the efficiency of cellulose decomposition: both soils produce equally active communities. Unexpectedly, the resulting communities trained on oats were more effective on hemp than the communities trained on hemp. In general, the usage of pre-trained microbial communities increases the efficiency of decomposition.

Remote Sensing of Depth-Induced Variations in Soil Organic Carbon Stocks Distribution Within Different Vegetated Landscapes

The preservation and augmentation of soil organic carbon (SOC) stocks is critical to designing climate change mitigation strategies and alleviating global warming. However, due to the susceptibility of SOC stocks to environmental and topo-climatic variability and changes, it is essential to obtain a comprehensive understanding of the state of current SOC stocks both spatially and vertically. Consequently, to effectively assess SOC storage and sequestration capacity, precise evaluations at multiple soil depths are required. Hence, this study implemented an advanced Deep Neural Network (DNN) model incorporating Sentinel-1 Synthetic Aperture Radar (SAR) data, topo-climatic features, and soil physical properties to predict SOC stocks at multiple depths (0-30cm, 30-60cm, 60-100cm, and 100-200cm) across diverse land-use categories in the KwaZulu-Natal province, South Africa. There was a general decline in the accuracy of the DNN model's prediction with increasing soil depth, with the root mean square error (RMSE) ranging from 8.34 t/h to 11.97 t/h for the four depths. These findings imply that the link between environmental covariates and SOC stocks weakens with soil depth. Additionally, distinct factors driving SOC stocks were discovered in both topsoil and deep-soil, with vegetation having the strongest effect in topsoil, and topo-climate factors and soil physical properties becoming more important as depth increases. This underscores the importance of incorporating depth-related soil properties in SOC modelling. Grasslands had the largest SOC stocks, while commercial forests have the highest SOC sequestration rates per unit area. This study offers valuable insights to policymakers and provides a basis for devising regional management strategies that can be used to effectively mitigate climate change.

Fine root decomposition in forest ecosystems: an ecological perspective

Fine root decomposition is a physio-biochemical activity that is critical to the global carbon cycle (C) in forest ecosystems. It is crucial to investigate the mechanisms and factors that control fine root decomposition in forest ecosystems to understand their system-level carbon balance. This process can be influenced by several abiotic (e.g., mean annual temperature, mean annual precipitation, site elevation, stand age, salinity, soil pH) and biotic (e.g., microorganism, substrate quality) variables. Comparing decomposition rates within sites reveals positive impacts of nitrogen and phosphorus concentrations and negative effects of lignin concentration. Nevertheless, estimating the actual fine root breakdown is difficult due to inadequate methods, anthropogenic activities, and the impact of climate change. Herein, we propose that how fine root substrate and soil physiochemical characteristics interact with soil microorganisms to influence fine root decomposition. This review summarized the elements that influence this process, as well as the research methods used to investigate it. There is also need to study the influence of annual and seasonal changes affecting fine root decomposition. This cumulative evidence will provide information on temporal and spatial dynamics of forest ecosystems, and will determine how logging and reforestation affect fine root decomposition.

Bioactive Metabolites from Terrestrial and Marine Actinomycetes

Actinomycetes inhabit both terrestrial and marine ecosystems and are highly proficient in producing a wide range of natural products with diverse biological functions, including antitumor, immunosuppressive, antimicrobial, and antiviral activities. In this review, we delve into the life cycle, ecology, taxonomy, and classification of actinomycetes, as well as their varied bioactive metabolites recently discovered between 2015 and 2023. Additionally, we explore promising strategies to unveil and investigate new bioactive metabolites, encompassing genome mining, activation of silent genes through signal molecules, and co-cultivation approaches. By presenting this comprehensive and up-to-date review, we hope to offer a potential solution to uncover novel bioactive compounds with essential activities.