Nutrient-rich Substrate Research Articles

Characterization and improvement of the leavening capacity of <i>Saccharomyces cerevisiae</i> isolated from Nigerian indigenous alcoholic beverages using a chemical mutagen

Yeasts are widely distributed in nature and can be isolated from nutrient rich substrates such as fruit and vegetable, fermented foods and beverages. Yeasts have been employed for millions of years in biotechnological applications in the production of bread, beer and wine. Saccharomyces cerevisiae is most important species when it comes to practical application in industries. Many developing countries including Nigeria spent billions of dollars annually on importation of active dry yeasts used in their baking and brewery industries. In order to reverse this trend, an attempt was made at improving the leavening capacity of S. cerevisiae isolated from locally made traditional alcoholic beverages by mutation induced by N-methyl-N-Nitro-N-Nitrosoguanidine (NTG). The yeast isolates were identified by their morphological properties and biochemical tests using standard methods. The viable counts of yeast isolated from the five alcoholic beverages employed in this study ranged between 1.4x107 and 2.4x108 CFU/mL. The yeast with the lowest percentage of occurrence (1.67%) are Geotricum candidum, Schizosaccharomyces japanicus, Sch. pombe, Candida intermedia etc. while S. cerevisiae had highest percentage of occurrence of 26.67%. S. cerevisiae PWII exhibited the highest dough rising ability among the parent strains, but S. cerevisiae M3 had the best dough rising power among the mutants. Physical examinations of the baked revealed that the bread samples produced with mutant strains compared favorably well with ones produced with commercial yeasts in terms of height, weight and volume. On the other hand bread samples produced using parent strains (PT 14 and PWII) had longer shelf life than bread from mutant and commercial strains. Sensory evaluation by taste panelists showed that the ranges of scores obtained are appearance (5.6-7.9), texture (6.3-8.1), taste (5.5-7.0), crumb (6.0-7.1) and overall acceptability (6.2-7.2). It could be concluded from this study that the leavening ability of S. cerevisiae could be enhanced by chemical mutagens and therefore could by employed in bread baking.

Emerging technologies are revolutionizing the rootstock rooting process in agricultural engineering through in vitro techniques

This article endeavors to showcase the seamless integration of cutting-edge technologies into the agricultural sector, with a specific emphasis on their application within biotechnology laboratories specializing in in vitro cultivation. The pioneering technology at the heart of this project centers on the automated detection of viral symptoms in micro-cut rootstocks grown in nutrient-rich substrates. Furthermore, we will delve into a comparative analysis, contrasting laboratories equipped with automated processes against those devoid of such advancements, specifically in the context of in vitro cultivation of subject-rooted plants in identical nutrient-rich environments. The anticipated annual financial gains stemming from the incorporation of an automated system into the in vitro laboratory are projected to reach an impressive 1.8 million Russian rubles.

Growth and metabolic behavior of probiotic Bifidobacterium longum subsp. longum in minimally supplemented soy (tofu) whey

Soy (tofu) whey is a liquid side-stream from tofu production. It is a nutrient-rich substrate that can be converted into beverages by fermentation. In this study, soy whey media supplemented with various nutrients (control, glucose, glucose + cysteine-HCl (GC), glucose + cysteine-HCl + yeast extract (GCY)) were evaluated as fermentation substrates for probiotic Bifidobacterium longum subsp. longum BB536. GC and GCY facilitated strain BB536 growth leading to the production of acetic and lactic acid. However, there was no significant decrease in sugar content after fermentation, while succinic acid and selected amino acids such as cysteine showed significant decreases after fermentation. Vitamin B12 (2.12 µg/L) was found only in fermented GCY samples. Endogenous volatile compounds such as heptanal and hexenal in tofu whey were reduced to low or trace levels while short-chain fatty acids, 2,3-butanedione and volatile sulfur compounds such as hydrogen sulfide and 3-methylthiophene were produced. Iron and potassium contents in the fermented soy whey increased after fermentation. This research provides further insights into the possibility of utilizing B. longum BB536 to ferment soy whey into a novel functional beverage or ingredient.

Functional, nutritional, and technological potential of quinoa through lactic acid fermentation: a review

Quinoa is an ancestral Andean grain of great importance due to its nutritional potential, cultivated in the Andean region for many years. Lactic acid fermentation may be a cost-effective processing alternative to improve quinoa-derived or gluten-free products, as it has been used in different cereals to enhance physicochemical and sensory characteristics. This review presents the nutritional importance of quinoa, the key indicators that can affect homofermentation, the analysis of different studies that have worked with this pseudocereal as a substrate for the development of various fermented products such as sourdoughs from quinoa flour for bread and other baked goods, beverages, pasta, baked products in combination with other pseudocereals and buckwheat, and soy-based beverages. The results reveal that quinoa is a nutrient-rich substrate for lactic acid bacteria, and fermentation generates nutritional changes by increasing certain macronutrients and/or bioactive compounds through bacterial metabolism and starch hydrolysis. Additionally, it improves functional, technological, and sensory properties due to starch modification and metabolite production. This presents a promising alternative in quinoa processing and the development of functional foods.

PHB production from food waste hydrolysates by Halomonas bluephagenesis Harboring PHB operon linked with an essential gene

Food wastes can be hydrolyzed into soluble microbial substrates, contributing to sustainability. Halomonas spp.-based Next Generation Industrial Biotechnology (NGIB) allows open, unsterile fermentation, eliminating the need for sterilization to avoid the Maillard reaction that negatively affects cell growth. This is especially important for food waste hydrolysates, which have a high nutrient content but are unstable due to batch, sources, or storage conditions. These make them unsuitable for polyhydroxyalkanoate (PHA) production, which usually requires limitation on either nitrogen, phosphorous, or sulfur. In this study, H. bluephagenesis was constructed by overexpressing the PHA synthesis operon phaCABCn (cloned from Cupriavidus necator) controlled by the essential gene ompW (encoding outer membrane protein W) promoter and the constitutive porin promoter that are continuously expressed at high levels throughout the cell growth process, allowing poly(3-hydroxybutyrate) (PHB) production to proceed in nutrient-rich (also nitrogen-rich) food waste hydrolysates of various sources. The recombinant H. bluephagenesis termed WZY278 generated 22 g L−1 cell dry weight (CDW) containing 80 wt% PHB when cultured in food waste hydrolysates in shake flasks, and it was grown to 70 g L−1 CDW containing 80 wt% PHB in a 7-L bioreactor via fed-batch cultivation. Thus, unsterilizable food waste hydrolysates can become nutrient-rich substrates for PHB production by H. bluephagenesis able to be grown contamination-free under open conditions.

Lignin-Modifying Enzymes in Scedosporium Species.

Scedosporium species are usually soil saprophytes but some members of the genus such as S. apiospermum and S. aurantiacum have been regularly reported as causing human respiratory infections, particularly in patients with cystic fibrosis (CF). Because of their low sensitivity to almost all available antifungal drugs, a better understanding of the pathogenic mechanisms of these fungi is mandatory. Likewise, identification of the origin of the contamination of patients with CF may be helpful to propose prophylactic measures. In this aim, environmental studies were conducted demonstrating that Scedosporium species are abundant in human-made environments and associated with nutrient-rich substrates. Although their natural habitat remains unknown, there is accumulated evidence to consider them as wood-decaying fungi. This study aimed to demonstrate the ability of these fungi to utilize lignocellulose compounds, especially lignin, as a carbon source. First, the lignolytic properties of Scedosporium species were confirmed by cultural methods, and biochemical assays suggested the involvement of peroxidases and oxidases as lignin-modifying enzymes. Scedosporium genomes were then screened using tBLASTn searches. Fifteen candidate genes were identified, including four peroxidase and seven oxidase genes, and some of them were shown, by real-time PCR experiments, to be overexpressed in lignin-containing medium, thus confirming their involvement in lignin degradation.

Evaluation of the Biostability of Elodea (Egeria densa) and Orange Peel as Bioadsorbent Materials for Pb (II) and Cr (III) in Solution

A variety of plant-based materials can be used in innovative methods to treat water pollution through bio-adsorption. This work evaluated, under lab conditions, the presence of native microorganisms in orange peel (OP) and elodea (Egeria densa, ELO), the aerobic degradation and biostability of the bio-adsorbents, and the contribution of microorganisms to the bio-adsorption of Pb (II) and Cr (III). The microbial characterization and biostability of OP and ELO were conducted using 2 g of dried bio-adsorbent and a solution of the metallic ions at 450 mg/L. ELO had a larger number of bacteria, fungi, and yeast than OP. After 2 hours of contact with a 450 mg/L Pb (II) and Cr (III) solution, this value decreased by 80-86% in both bio-adsorbents. After 25 days, the microorganisms showed adaptation to the Pb (II) and Cr (III) concentrations. According to the bio-degradation test, OP had a stability of over 7,01 months, while that of ELO was 2,61 months, with a CO2 value of 1 439,9 mg after 46 days of incubation. The microorganisms tolerated a high metal concentration, but they did not contribute significantly to Cr (III) bio-adsorption in ELO. The microorganisms present in the adsorbents affect the stability of the materials, as the bio-adsorbents provide a nutrient-rich substrate. OP had higher bio-stability and could be used in pilot tests for the treatment of metal-polluted water.

Effect of substrate fertility on tank-bromeliad performances

Members of the plant family Bromeliaceae can uptake nutrients directly from their leaves via leaf absorbing trichomes and their roots have long been reduced to anchorage function, thus overlooked. Recently, evidence has accumulated for a significant role for the roots of some species of tank bromeliads in both water and nutrients absorption. However, to date, little attention has been paid to the importance of the substrate fertility for the structure of the roots and the growth and performances of tank bromeliads. This study investigated the effect of substrate fertility on Aechmea aquilega regarding leaf and root traits, nutrient content, and growth. Seeds of this tank bromeliad were sowed in a greenhouse in French Guiana in three different substrates: a nutrient-poor, a nutrient-rich and a mixed substrate. The performances of 15-month-old A. aquilega were assessed by measuring leaf and root traits related to nutrient acquisition and resources capture. We show that plants growing in nutrient-poor substrate grew twice slower and were smaller than plants grown on the nutrient-rich substrate with fewer leaves and roots, lower total dry mass, and smaller leaves and root length. Overall, 70% of measured traits responded significantly to the experimental treatments indicating that the response of A. aquilega to nutrient availability is a combination of physiological processes, leaf and root structure, and chemistry. This study is the first to show that the fertility of the substrate on which the bromeliad A. aquilega grows has a strong and lasting effect on the plant performances and may be a relevant factor for bromeliad ecology.

Diversity and putative metabolic function of prokaryotic communities in tank bromeliads along an elevation gradient in tropical Mexico.

Tank bromeliads are unique canopy microhabitats that offer freshwater and organic nutrient-rich substrates in the Neotropics. In them it is possible to thoroughly characterize environmental factors and species composition of terrestrial and aquatic biota. Therefore, these plants have been used as natural models to study how communities are distributed and assembled. Here we used amplicon sequencing of the 16S rRNA gene and their functional annotations to study the diversity and metabolic potential of prokaryotic communities in tank bromeliads in five different forests along an elevation gradient in tropical Mexico. Furthermore, we analyzed the effects of vegetation type and environmental factors inside the tanks on prokaryotic composition. We found a high prokaryotic diversity in tank bromeliads along the elevation gradient. Prokaryotes commonly observed in acidic environments rich in organic carbon, and the potential pathogen Pasteurella multocida, were present in all samples, but few amplicon sequence variants were shared between forests. The prokaryotic composition was affected by forest type, and comparisons against null models suggest that it was shaped by non-neutral processes. Furthermore, prokaryotic community changes significantly covaried with tank water temperature, pH, and inorganic carbon. We found a high diversity of putative metabolic groups dominated by chemoheterotrophs and fermenters, but taxonomic groups involved in nitrogen and sulfur cycling were also present in all samples. These results suggest that tank bromeliads promote taxonomic and metabolic diversity of the prokaryotic community at a local and regional scale and play an important role in the biogeochemistry of forest canopies in the Neotropics.

Proposal (29) to conserve the name Omphalodo nitidae-Coryletum avellanae Amigo, G. Azcárate et Romero 1994 with a conserved type

The association Omphalodo nitidae-Coryletum avellanae was defined by assembling relevés on (mainly) Corylus avellana woods on nutrient-rich substrates in the westernmost part of the Cantabrian Range (NW Spain). However, a mesophytic oak forest dominated by Quercus robur (with noteworthy amount of Corylus avellana in the undercanopy) was selected as its holotype. The most common interpretation of this association in the subsequent literature has been as seral Corylus avellana forests. For this reason, we propose the application of article 53 of the ICPN (4th ed.), which allows the name to be maintained with a new nomenclatural type based on the more recent interpretation of this syntaxon. (29) Omphalodo nitidae-Coryletum avellanae Amigo, G. Azcárate et Romero 1994, typus cons. propos. Typus: Amigo et al. (1994), table 2: rel. 4 (typus cons. propos.) Taxonomic reference: Castroviejo et al. (1986–2020). Syntaxonomic reference: Rivas-Martínez (2011). Abbreviations: ICPN = International Code of Phytosociological Nomenclature.

Мохоподібні Івано-Франківської області: структурний аналіз і особливості регіонально рідкісних видів

On the territory of the Ivano-Frankivsk region were found 66 species of regionally rare bryophytes. Among them, mosses predominat, but the proportion of liverworts is significant. Based on the analysis of the taxonomic structure, it was established that the liverworts (Marchantiophyta) belong to 2 classes, 4 orders, 13 families, 16 genera, 19 species; mosses (Bryophyta) – to 3 classes, 12 orders, 20 families, 38 genera, 47 species. According to the number of species, bryophyte families are located as follows: Pottiaceae – 11 species (16,8 %); Brachytheciaceae – 5 (7,6 %); Cephaloziaceae and Splachnaceae – 3 (4,6 %), the rest of the families are oligo- and monospecies. Among rare species, the boreal geographical element predominates (27 species, 41,0 %), the following arid (11 species, 16,7 %), and nemoral (10 species, 15,1 %). The analysis of ecological groups of mosses and liverworts by type, chemistry, humidity, trophic and illuminance of the substrate is carried out. It was found that most rare species belong to the epigeous heliophytes. The chemistry of the substrate is dominated by acidoneutrophils, which grow on substrates with pH values from 3 to 7. The trophic dominance of species that occur on relatively nutrient-rich substrates; the humidity of the habitats is dominated by mesophytes, a significant hygrophytic group of species. Among the rare bryophytes, species with life forms of low turf, which occur mainly on soil and rocks, predominate. Most rare species with life forms of mats, tall turfs and wefts are confined to wetlands (swamps and shores of reservoirs), a significant part mat and short turfs – to rock outcrops. Sexual types of bryophytes and the presence of specialized organs of asexual reproduction have been determined. Rare species, confined to wet and humid ecotopes, are particularly sensitive to any changes in hydrothermal conditions.

Black soldier fly, Hermetia illucens as a potential innovative and environmentally friendly tool for organic waste management: A mini-review.

The application of black soldier fly (BSF), Hermetia illucens based technology to process organic wastes presents a practical option for organic waste management by producing feed materials (protein, fat), biodiesel, chitin and biofertilizer. Therefore, BSF organic wastes recycling is a sustainable and cost-effective process that promotes resource recovery, and generates valuable products, thereby creating new economic opportunities for the industrial sector and entrepreneurs. Specifically, we discussed the significance of BSF larvae (BSFL) in the recycling of biowaste. Despite the fact that BSFL may consume a variety of wastes materials, whereas, certain lignocellulosic wastes, such as dairy manure, are deficient in nutrients, which might slow BSFL development. The nutritional value of larval feeding substrates may be improved by mixing in nutrient-rich substrates like chicken manure or soybean curd residue, for instance. Similarly, microbial fermentation may be used to digest lignocellulosic waste, releasing nutrients that are needed for the BSFL. In this mini-review, a thorough discussion has been conducted on the various waste biodegraded by the BSFL, their co-digestion and microbial fermentation of BSFL substrate, as well as the prospective applications and safety of the possible by-products that may be generated at the completion of the treatment process. Furthermore, this study examines the present gaps and challenges on the direction to the efficient application of BSF for waste management and the commercialization of its by-products.

The Dung Beetle Oxyomus of Taiwan (Coleoptera: Scarabaeidae): Review of the Fauna, a New Species and its Larva Associated by DNA Barcoding.

The Taiwanese fauna of the dung beetle genus Oxyomus Dejean, 1833 (Coleoptera: Scarabaeidae: Aphodiinae) is reviewed based on museum specimens and newly collected material. Four species, all endemic to Taiwan, are recognized, one of which is newly described here: O. alligator sp. nov. Remaining species are diagnosed, compared with similar relatives from outside of Taiwan, and their distribution is mapped. We show that Taiwanese Oxyomus species form three distinct morphological groups, similar to species from Japan, SE Asia and Malay Archipelago, respectively, indicating a possible composite origin of Taiwanese fauna. The species occur in submontane and montane forests at altitudes of 700-2550 m including the secondary Cryptomeria ones. Available data confirm their association with dung of various forest mammals (monkeys, muntjacs and serows), although the discovery of larvae in sifted forest leaf litter may indicate they can also develop in nutrient-rich substrate around the dung. The larva of O. alligator sp. nov. is described in detail, based on the larval specimens associated with adults by DNA barcodes. Larvae of Oxyomus alligator sp. nov. are similar to those of the European O. sylvestris (Scopoli, 1763), with important differences only found on maxilla and abdominal apex.

Byrsonima crassifolia seedlings growth on ground basalt rock

Ground basalt rock may represent a labile reservoir of nutrients, providing a low-cost, nutrient-rich substrate for seedling formation and plant growth. The study aimed to evaluate the development of a native plant murici [Byrsonima crassifolia (L.) H.B.K.] seedlings using two different application rates of ground basalt rock with two particles sizes. The experiment was performed in a greenhouse, in which treatments were arranged in a random block design with five replications in a factorial scheme (2 x 5 + 1), with five doses of finely ground basaltic rock (0.42; 1.04; 2.08; 4.17 and 8.33 g kg-1), two grain sizes (G1 Ø < 0.05 and G2 Ø < 0.10 mm mesh), and a treatment with soil without rock powder addition (the control 0.0 g kg-1 of rock powder). The seedlings were cultivated in substrate incubated for 120 days with the ground basaltic rock. Six months after the seedlings were planted variables involving growth and nutrient content variables were evaluated. Grain size affected nutrient availability from finely ground rock (Ca, Mg, Fe, and Zn). The growth of murici seedlings linear increase with ground basaltic rock application rates, with better results when a 0.05 mm grain size was used.

Effect of lignosulfonate application to sandy soil on plant nutrition and physiological traits

The application of nutrient-rich substrates to soils characterized by low natural fertility is discussed as a strategy to improve soil fertility and, consequently, affect plant physiological traits. This study aimed to evaluate if sodium lignosulfonate (LS), a by-products of pulp and paper industry, may improve plant ecophysiological traits under contrasting nutrient conditions. A pot culture experiment was conducted with cucumber plants, using LS concentrations of 0, 1, 2.5, 5, and 10 vol.% in sandy soil, and two soil nutrient levels: sufficient and low nutrient availability (SNA and LNA, accordingly). The LS increased N and P content in SNA leaves when 1% of LS was used and decreased N content in LNA leaves regardless of soil LS content. The LS did reduce mass-, N-, and P-based respiration rates of the SNA leaves, and increased the N-based respiration rate under LNA. The LS did not have a significant impact on the ratio of respiration to photosynthesis in SNA leaves, but decreased it under LNA. The LS application contributed to a slight activation of some physiological processes in LNA plants, but it was not successful to recover these activities to the level of plants grown under SNA.

Effects of three-dimensional soil heterogeneity and species composition on plant biomass and biomass allocation of grass-mixtures.

Soil heterogeneity significantly affects plant dynamics such as plant growth and biomass. Most studies developed soil heterogeneity in two dimensions, i.e. either horizontally or vertically. However, soil heterogeneity in natural ecosystems varies both horizontally and vertically, i.e. in three dimensions. Previous studies on plant biomass and biomass allocation rarely considered the joint effects of soil heterogeneity and species composition. Thus, to investigate such joint effects on plant biomass and biomass allocation, a controlled experiment was conducted, where three levels of soil heterogeneity and seven types of species compositions were applied. Such soil heterogeneity was developed by filling nutrient-rich and nutrient-poor substrates in an alternative pattern in pots with different patch sizes (small, medium or large), and species compositions was achieved by applying three plant species (i.e. Festuca elata, Bromus inermis, Elymus breviaristatus) in all possible combinations (growing either in monoculture or in mixtures). Results showed that patch size significantly impacted plant biomass and biomass allocation, which differed among plant species. Specially, at the pot scale, with increasing patch size, shoot biomass decreased, while root biomass and R:S ratio increased, and total biomass tended to show a unimodal pattern, where the medium patch supported higher total biomass. Moreover, at the substrate scale, more shoot biomass and total biomass were found in nutrient-rich substrate. Furthermore, at the community scale, two of the three target plant species growing in monoculture had more shoot biomass than those growing together with other species. Thus, our results indicate soil heterogeneity significantly affected plant biomass and biomass allocation, which differ among plant species, though more research is needed on the generalization on biomass allocation. We propose that soil heterogeneity should be considered more explicitly in studies with more species in long-term experiments.

Optimization and scale-up of \u03b1-amylase production by Aspergillus oryzae using solid-state fermentation of edible oil cakes

BackgroundAmylases produced by fungi during solid-state fermentation are the most widely used commercial enzymes to meet the ever-increasing demands of the global enzyme market. The use of low-cost substrates to curtail the production cost and reuse solid wastes are seen as viable options for the commercial production of many enzymes. Applications of α-amylases in food, feed, and industrial sectors have increased over the years. Additionally, the demand for processed and ready-to-eat food has increased because of the rapid growth of food-processing industries in developing economies. These factors significantly contribute to the global enzyme market. It is estimated that by the end of 2024, the global α-amylase market would reach USD 320.1 million (Grand View Research Inc., 2016). We produced α-amylase using Aspergillus oryzae and low-cost substrates obtained from edible oil cake, such as groundnut oil cake (GOC), coconut oil cake (COC), sesame oil cake (SOC) by solid-state fermentation. We cultivated the fungus using these nutrient-rich substrates to produce the enzyme. The enzyme was extracted, partially purified, and tested for pH and temperature stability. The effect of pH, incubation period and temperature on α-amylase production using A. oryzae was optimized. Box–Behnken design (BBD) of response surface methodology (RSM) was used to optimize and determine the effects of all process parameters on α-amylase production. The overall cost economics of α-amylase production using a pilot-scale fermenter was also studied.ResultsThe substrate optimization for α-amylase production by the Box–Behnken design of RSM showed GOC as the most suitable substrate for A. oryzae, as evident from its maximum α-amylase production of 9868.12 U/gds. Further optimization of process parameters showed that the initial moisture content of 64%, pH of 4.5, incubation period of 108 h, and temperature of 32.5 °C are optimum conditions for α-amylase production. The production increased by 11.4% (10,994.74 U/gds) by up-scaling and using optimized conditions in a pilot-scale fermenter. The partially purified α-amylase exhibited maximum stability at a pH of 6.0 and a temperature of 55 °C. The overall cost economic studies showed that the partially purified α-amylase could be produced at the rate of Rs. 622/L.ConclusionsThe process parameters for enhanced α-amylase secretion were analyzed using 3D contour plots by RSM, which showed that contour lines were more oriented toward incubation temperature and pH, having a significant effect (p < 0.05) on the α-amylase activity. The optimized parameters were subsequently employed in a 600 L-pilot-scale fermenter for the α-amylase production. The substrates were rich in nutrients, and supplementation of nutrients was not required. Thus, we have suggested an economically viable process of α-amylase production using a pilot-scale fermenter.

SIGNALING PATHWAYS OF CONIDIAL GERMINATION AND GROWTH OF BOTRYTIS CINEREA: HOST DETECTION, PATHOGENESIS ON VITIS VINIFERA AND PREFERENCE FOR WINE GRAPES

Botrytis cinerea is a phytopathogenic filamentous fungus that infects and causes severe damages to numerous crops. However, the European grapevine ( Vitis vinifera ) remains the major host for the pathogen. Botrytis infects mainly ripe grapes (usually over 10 degrees Baume) unless primary infections by other fungi, or infestations by viticultural insect pests, or mechanical damages have occurred. The disease is commonly known in viticulture as “Botrytis bunch rot” or “grey mold” and can spread rapidly causing devastating losses on the field and post-harvest. Regardless of its generalist action, B. cinerea must develop strategies to recognise and invade its host. The fungus responds to physical and chemical stimuli, emanated from the environment to activate spore germination and growth. Once a signal from the external environment meets a target molecule of the cell, the signaling process begins. The target molecule is a protein that acts as a receptor. The physical and chemical signals that stimulate conidial germination depend on factors such as surface hardness, surface hydrophobicity, carbon sources and nutrient-rich substrates. Among sugars, fructose is the best growth inducer of B. cinerea. Heterotrimeric guanine nucleotide binding proteins (G-proteins) are involved in the regulation of a range of functions including germination, growth and host detection. G-proteins consist of three subunits, α, β and γ. Two of these subunits attach to the cell membrane with small lipid tails. At rest, unit α is bound to Guanosine Diphosphate (GDP) and the G-protein is inactive. When an extracellular ligand binds to the receptor, the latter interacts with the G-protein and activates it, forcing the α subunit to excrete the bound GDP and replace it with Guanosine Triphosphate (GTP). In addition to signals that trigger spore germination, pathogenesis is also influenced by several biotic and abiotic factors. In general terms, interactions between pathogen, its potential host and the environment affect level, speed and nature of the infection and must be substantially considered in integrated control strategies.

Carbon, nitrogen, and phosphorus variation along a green roof chronosequence: Implications for green roof ecosystem development

While the developmental dynamics of ecosystems have been studied in many natural systems, it is unclear if these patterns are to be expected in engineered ecosystems where components have not co-developed over time. Green roofs often begin with a nutrient rich substrate that is paired with slow-growing plants adapted to nutrient poor conditions - perhaps resulting in different developmental dynamics than natural ecosystems. We evaluated changes over time in green roof nutrient content and vegetation communities using a chronosequence in southern Sweden of similarly designed but different aged green roofs spanning between 2 and 22 years. Substrate depth, substrate nitrogen (N), and total N pool sizes varied positively with roof age. These dynamics suggest an accumulation of 2.9 ± 1.1 g N/m2/yr with no indication of leveling off after 22 years. Plant N content (%) positively varied with roof age but plant biomass, plant nutrient pools, and plant diversity did not vary with age. These dynamics indicate a novel developmental scenario where the ecosystem begins with near-stable plant biomass but still accumulates N in the substrate at rates on par with many secondary successional systems. The apparent accumulation of N could not be accounted for by N deposition rates for the region, suggesting substantial N-fixation. The novel developmental dynamics outlined in this study point to the need for a new or expanded ecosystem developmental paradigm that better suits green roofs and perhaps other emerging engineered ecosystems.

Effects of three-dimensional soil heterogeneity on seed germination in controlled experiments

Abstract Aims Seed germinations react to their local growing conditions, but the impacts of soil heterogeneity on seed germinations are not well known. Methods Effects of three-dimensional soil heterogeneity on seed germinations of grasses species were explored, where two levels of such soil heterogeneity were created via alternatively filling nutrient-poor and nutrient-rich substrate in pot in all directions. Patch sizes of the two heterogeneity levels are around 7.5 and 15 cm, respectively. Fifty seeds of each of the grasses species (Lolium perenne and Elymus nutans) were set either in these heterogeneous soils or in petri dishes with distilled water. Seed germinations of these species were daily recorded. Important Findings We found that pots with smaller patches had relatively lower germination rate, which is consistent with our expectation that shorter distance between nutrient-rich and nutrient-poor patches in pots with smaller patches allows plants to reduce their germination rates and delay their germination, in order to reduce the negative impacts of the strong variation of soil resources in these pots. Our results also revealed that pots with smaller patches yielded more heterogeneous seed germination, i.e. seed germinations highly diverged among these pots. These findings highlight that the realistic three-dimensional design can improve our understanding of seed germination as driven by soil spatial heterogeneity.