Spore Density Research Articles

Perbanyakan Agen Hayati Trichoderma Sp. Menggunakan Media Beras di Laboratorium Pengamatan Hama dan Penyakit Tanaman Banyumas

The rhizosphere area of a plant is an area rich in microbes, one of which is a group of fungi. This practical work aims to multiply Trichoderma sp. in the rhizosphere of bamboo plants in the Jatilawang area using rice as a medium. This practical work uses rice and coconut media in conducting exploration. The results of practical work obtained spore density of Trichoderma sp. meet the standards for application in plants. Obstacles in exploring Trichoderma sp. is takes a long time.

Bracken fern does not diminish arbuscular mycorrhizal fungus inoculum potential in tropical deforested areas.

Tropical montane forests are threatened by uncontrolled fire events because of agricultural expansion. Consequently, deforested areas frequently are dominated by the bracken fern, Pteridium spp., for long periods, and forest regeneration is limited. Despite considerable research on bracken-dominated ecosystems, little is known about the relationship between bracken mycorrhizal fungi and tree seedlings. Arbuscular mycorrhizal fungi (AMF) form symbiotic relationships with terrestrial plants, providing nutrients and protection against pathogens and promoting seedling growth and establishment. Therefore, AMF inoculum have high potential for forest restoration programs. Here, we compare the species diversity of AMF spores, root colonization, and seedling growth of Clusia trochiformis 1year after the addition of different liquefied root inocula: forest conspecific, forest heterospecific, and from Pteridium rhizomes. Thirteen morphospecies of arbuscular mycorrhizal fungi were identified on the roots of C. trochiformis, and Glomus spp. were the most abundant in all treatments. No differences were observed in spore species richness and diversity among treatments, but spore density was the highest subsequent to the Pteridium inoculum. There was no significant difference in mycorrhizal root colonization and seedling growth of C. trochiformis among inoculated treatments. We found a positive relation between root colonization and total biomass. This study shows that the AMF communities in bracken areas and forests present similar characteristics and that the bracken fern does not limit AMF inoculum potential, favouring seedling growth of Clusia.

Diversity of Endomycorrhizas in Falcataria moluccana (Miq.) Barneby & J.W. Grimes Affected by Gall Rust Disease in Laguna, Philippines

Endomycorrhizas or arbuscular mycorrhizal fungi (AMF) are microfungal associates known to facilitate nutrient absorption in higher plants that benefit growth and survival. Studies have shown that they can induce systemic host resistance against pathogenic fungi, but little information is known about its contributions to gall rust disease in Falcataria moluccana, an important plantation tree species. This paper investigated the community of endomycorrhizas under F. moluccana stand affected by Uromycladium rust from a secondary-growth forest in Laguna, Philippines. Three transects (1.5 km) were established wherein matured F. moluccana trees (n = 32) were assessed for gall rust incidence and disease severity index (DSI) using a five-point rating scale to categorize infection. Composite rhizosphere samples were collected from nine sampling plots for macronutrient analysis and AMF assessment. Endomycorrhizal spores were isolated from dissolved 100-g soil solution following wet-sieving and decanting method then characterized morphologically for identification, spore density, and diversity analysis. Results of the tree health survey showed 100% disease incidence with moderate infection (DSI = 30–44). Overall, 13 morphospecies of endomycorrhizal fungi were identified from three orders and five families. The eight genera associated with F. moluccana were Acaulospora, Ambispora, Diversispora, Enthrophospora, Funneliformis, Gigaspora, Glomus, and Rhizophagus. The Shannon diversity index (H’) revealed a significant (p< 0.002) difference in all sites [F (2, 31) = 7.46]. The findings suggest that species abundance and density of AMF fungi are related to soil phosphorous and the severity of gall rust. This study presents the potential of important AMF species for the integrated management of gall rust disease affecting F. moluccana.

Effects of biochar amendment on wheat production, mycorrhizal status, soil microbial community, and properties of an Andisol in Southern Chile

Biochar (BC) production from agroforestry wastes and mycorrhizal fungi are potentially important agricultural practices for improving crops yields and increasing phosphorus (P) in volcanic soils. This study aimed to test the effect of BC application on wheat biomass and grain yield production, indigenous arbuscular mycorrhizal (AM) fungi propagules and soil microbial community and related to soil quality properties of an Andisol in Southern Chile. Biochars (BCs) were produced from oat hulls (OBC) and pine bark (PBC). Doses of 0, 5, 10, and 20 Mg ha−1 of BCs were applied on soil using wheat as the test crop. Wheat biomass (root and shoot portion) and grain yield, AM root colonization, spore, mycelium density, and glomalin content (glomalin related soil protein, EE-GRSP) were measured and related with soil quality properties such as bulk density, water-stable aggregates (WSA), and water holding capacity (WHC). The OBC had a significantly higher macronutrients content (N, P, K) than PBC. The highest dose of both BCs significantly improved shoot and root biomass and wheat grain yield. Application of 20 Mg ha−1 of OBC and PBC increased AM spore density and root colonization relative to control treatment. In the same way, the BC application significantly affects the AM mycelium density. The results showed that the application of higher BC dose changed the soil microbial community. The use of BCs in this volcanic soil is an effective strategy to increase wheat biomass, increase grain yield production, stimulate the indigenous AM fungi activity, enhance soil quality properties, and increase the sustainability levels of agricultural systems.

Effectiveness Test of Trichoderma harzianum on The Development of Anthracnose Disease (Colletotrichum musae) of Ambon Banana

The decrease in the quality of bananas can be caused by the attack of the pathogen Colletotrichum musae which causes anthracnose disease. The use of the antagonist fungus Trichoderma harzianum can be relied upon to control this disease. This study aimed to obtain a more effective level of T. harzianum spore density to suppress the development of anthracnose disease in Ambon bananas. The treatment tested was T. harzianum with five levels of spore density, namely 105, 106, 107,108, and 109 spore/mL, designed using a completely randomized design with five replications. The variables observed were the incubation period and the intensity of the disease. The results showed that the spore density of 109 was effective in suppressing the development of anthracnose disease by inhibiting the incubation period to 3.85 days and suppressing the intensity of the disease to 41.4%.Keywords: Banana, Trichoderma harzianum, Anthracnose, Colletotrichum musae

Factors Affecting the Epizootics of Entomopathogenic Fungi-A Review

Entomopathogenic fungi (EPF) specifically infect and kill insects can serve as a potential biological control agent. Several biotic and abiotic factors affect their occurrence, persistence, and epizootics caused by them. In biotic factors, fungi characters (host range, latency, spore density and dispersal, mainly host-pathogen compatibility), insect host factors (behavioral, morphological, and physiological), plant-mediated effects (plant architecture, surface chemistry, and leaf topology) are included supports or causes the barrier to mycobiopesticide. Abiotic factors which affect the EPF field persistence are mainly environmental (temperature, sunlight, humidity, rainfall) physical and chemical soil properties (soil texture, pH, E.c, moisture, C/N content, and organic matter) that greatly influence the entomopathogenic fungi. To use them as biocontrol agents, we have to overcome these factors by providing them nutrients, protectants, and using different control practices.

Effect of High-Temperature Stress on Plant Physiological Traits and Mycorrhizal Symbiosis in Maize Plants.

Increasing high temperature (HT) has a deleterious effect on plant growth. Earlier works reported the protective role of arbuscular mycorrhizal fungi (AMF) under stress conditions, particularly influencing the physiological parameters. However, the protective role of AMF under high-temperature stress examining physiological parameters with characteristic phospholipid fatty acids (PLFA) of soil microbial communities including AMF has not been studied. This work aims to study how high-temperature stress affects photosynthetic and below-ground traits in maize plants with and without AMF. Photosynthetic parameters like quantum yield of photosystem (PS) II, PSI, electron transport, and fractions of open reaction centers decreased in HT exposed plants, but recovered in AMF + HT plants. AMF + HT plants had significantly higher AM-signature 16:1ω5cis neutral lipid fatty acid (NLFA), spore density in soil, and root colonization with lower lipid peroxidation than non-mycorrhizal HT plants. As a result, enriched plants had more active living biomass, which improved photosynthetic efficiency when exposed to heat. This study provides an understanding of how AM-mediated plants can tolerate high temperatures while maintaining the stability of their photosynthetic apparatus. This is the first study to combine above- and below-ground traits, which could lead to a new understanding of plant and rhizosphere stress.

Dynamics of arbuscular mycorrhizal fungi and glomalin in the rhizosphere of Gymnocarpos przewalskii in Northwest Desert, China

Relict plants, remnants of Tertiary flora, survived geochronological ages, however, studies intended to ascertain the background of their fungal symbionts are limited. Different from many other relict plants, Gymnocarpos przewalskii Maxim. inhabits arid deserts region, mainly distributed in northwest China. In order to inquire the arbuscular mycorrhizal fungi (AMF) associated to G. przewalskii and their ecological significance in desert ecosystems, the seasonal dynamics of AMF and glomalin were surveyed in Anxi and Minqin in Gansu Province, northwest China. Soil samples in the rhizosphere of G. przewalskii were collected in July, September and December 2019, respectively. In total, 41 and 46 AMF species were identified via morphological techniques in Anxi and Minqin, respectively. Meanwhile, high throughput sequencing (HTS) data diagnosed 29 and 61 AMF OTUs in Anxi and Minqin, respectively. Glomus was the dominant genus in different seasons and locations in both morphological investigation and HTS data. AMF colonization (44.67–75.30%) and spore densities (19–248 per 20 g soil) varied sharply among seasons and locations. AMF colonization and spore densities showed significant positive correlations to most edaphic factors, except soil carbon: nitrogen ratio. Glomalin-related soil protein (GRSP) dramatically contributed to local soil carbon pool (51.54% in Anxi, 40.37% in Minqin), and the GRSP contents in soil were significantly affected by soil properties, season, and location. Random forest analysis indicated that soil humidity and total GRSP were the main factors shaping AMF communities. Our results showed that AMF colonization, spore density, and species diversity were higher and AMF community composition was less variable in Minqin where the soil nutrition levels were lower, which emphasized the necessity of AMF symbiosis for plants in harsh environments. The present research demonstrated the seasonal dynamics of soil AMF communities and glomalin and determined influential environmental factors in desert ecosystems. Our findings provide novel views on desert soil resource management and relict plant protection from an aspect of plant-AMF symbiosis.

Responses of Arbuscular Mycorrhizal Fungi Diversity and Community to 41-Year Rotation Fertilization in Brown Soil Region of Northeast China.

Arbuscular mycorrhizal fungi (AMF) play vital roles in the growth and development of plants, ecosystem sustainability, and stability in agroecosystem, such as transporting nutrients to host plants, improving soil physical structure, and enhancing the stress resistance of host plants. However, the effects of fertilization on AMF diversity and community in brown soil areas are still unclear. The purpose of this study is to explore changes in AMF diversity and community structures and finding out the factors that influenced the changes after 41 years of fertilization in brown soil. Samples were collected from five treatments of the long-term fertilization experiment in June 2019, including CK (no fertilizer), N (mineral nitrogen fertilizer), NP (mineral nitrogen and phosphate fertilizer), M (pig manure), and MNP (pig manure, mineral nitrogen, and phosphate fertilizer). Illumina HiSeq sequencing was used to determine AMF diversity and community structure. The relationship between AMF communities in soil and roots and environmental factors was analyzed by redundancy analysis. The results showed that the soil nutrient content of manure treatments was generally higher than that of chemical fertilizer treatments and no fertilizer treatment. Long-term fertilization increased AMF spore density, which increased with the increase of soil fertility. The moderate content of soil available phosphorus was beneficial to the colonization of AMF. AMF diversity in soil decreased with soil fertility, but AMF diversity in roots was influenced only by soil nitrate–nitrogen and pH. Glomus was the dominant genus in both soil and root samples. AMF community structure in soil and roots had a different response to long-term fertilization. Application of manure had a greater impact on AMF community structure in soil, whereas application of exogenous phosphate fertilizer had a greater impact on that in roots. Soil ammonium nitrogen, nitrate–nitrogen, total nitrogen, organic carbon, total potassium, and available potassium were the most important factors that influenced taxa of AMF in soil, whereas soil ammonium nitrogen, nitrate–nitrogen, total nitrogen, organic carbon, total potassium, available potassium, available phosphorus, and plant phosphorus and potassium content were the most important factors influencing taxa of AMF in maize roots under long-term fertilization in brown soil.

Mycorrhizal fungi Glomus spp. propagation in zeolite enriched with mycorrhiza helper bacteria for controlling nematode in coffee

Arbuscular mycorrhizal fungi (AMF) play a role in suppressing the nematode Pratylenchus coffeae. Mycorrhizal helper bacteria (MHB) can increase the effectiveness of AMF to control the diseases. The experimental purpose was to increase the spore population of AMF Glomus spp. in zeolite-based formulation inoculated with liquid consortia of Pseudomonas diminuta and Bacillus subtilis as MHB. The experimental design was a completely random design with six treatments consisted of 106, 107, 108, and 109 CFU/mL MHB liquid inoculants. The control treatments were water and 2% molasses. All treatments were replicated four times. A total of 300 mL/pot Liquid inoculant of MHB have been inoculated a three day before transplanting the maize seedling to the Zeolite inoculated with Glomus spp. in the pot. One month after MHB inoculation, Glomus formulation in Zeolite with different levels of MHB increased the degree of infection. Three months after MHB inoculation, spore content in Zeolite increased. The density of P. diminuta and B. subtilis in zeolite-based mycorrhizal inoculant increased at the end of the experiment. Liquid inoculant MHB contained 108 CFU/mL enhanced spora number fourth times compared to the control. This experiment suggests that P. diminuta and B. subtilis were effective to increase the spore density of AMF inoculant.

Harnessing Acremonium zonatum (Sawada) Gams oil formulations as water hyacinth control mycoherbicides.

The effect of formulating Acremonium zonatum (Saw.) Gams in corn oil, mineral oil and glycerol was determined in a glasshouse at Maseno University Botanic Garden and laboratory. The study was situated at latitude -100’ 00’’ S and longitude 340 36’ 00’’E. A. zonatum was aseptically isolated from symptomatic plants and inoculated upon healthy water hyacinth plants in a CRD experiment. Data was analyzed using SPSS version 20 computer software. Oil and spore density effects were statistically significant at p < 0.05. The main effect of oil yielded an effect size of 0.281 indicating that 28.1 % of the variance in disease severity was explained by the oil formulation (F(2, 28) = 5.459, p = 0.01). Spore density yielded an effect size of 0.326 indicating that 32.6% of the variance in the study was explained by spore density (F(3, 28) = 4.515, p = 0.011). The interaction effect was not significant (F(6, 28) = 0.199, p = 0.974) indicating that there was no combined effect for the kind of oil used in the formulation of the A. zonatum and the spore density. The results suggested that A. zonatum pathogenicity varies with different spore concentrations, 1x 108 spores/ml being the most potent. A. zonatum has favorable characteristics for consideration as a mycoherbicide. Corn oil as formulation material was concluded to be the best formulation material for A. zonatum.

Büyük ölçekli tarımsal uygulama için endofiz mikorrhizasının inokülum üretimi üzerinde substrat ve konak bitki olarak yer fıstığı atıklarının etkisi

A pot culture experiment was conducted to study the effect of soil amendment with different forms of groundnut waste on spore population and root infection of indigenous Arbuscular Mycorrhizal fungal species i.e. Glomus mosseae under polyhouse conditions. Two angiospermic plant species viz. sorghum and sesame were also examined for mycorrhization potential in the study. Observations were made for percent root colonization, spore density of AM fungi and the effectiveness of AM fungi on the shoot and root biomass of both host plants. The results indicated that AM fungal spore population and colonization levels were substantially enhanced by the application of compost groundnut waste as a substrate over dry groundnut waste. Among growth parameters, plant height, root length and plant biomass were recorded more in sorghum than Sesame. On the whole, mycorrhization was reported the highest with 75 g/pot concentration of waste. Also, Sorghum appeared to be a better host than sesame.

Infections of <i>Kudoa septempunctata</i> (Myxozoa: Multivalvulida) in Wild Grass Puffer <i>Takifugu alboplumbeus</i> and Japanese Whiting <i>Sillago japonica</i>

Kudoa septempunctata is an important myxozoan parasite in culture and capture fisheries as it causes food poisoning in humans. ​This species is generally considered a parasite of olive flounder Paralichthys olivaceus because K. septempunctata-related food poisoning cases are associated with consumption of raw infected P. olivaceus. ​However, the host range of K. septempunctata remains unclear. ​Moreover, there is scarce information on the lifecycle of the parasite, and this hinders the development of a fundamental prophylactic measure in fish farms. ​During the survey of wild fishes at a K. septempunctata endemic area, kudoid myxospores were detected in the somatic muscle of grass puffer Takifugu alboplumbeus and Japanese whiting, Sillago japonica. ​Our morphological, molecular, and histological analyses identified them as K. septempunctata. ​While the infection levels in T. alboplumbeus were higher (up to 92.3% prevalence) than those in S. japonica (23.8%), the maximum spore density in the muscle tissue was about 7×104/g in both fishes, which is far less than the food poisoning risk value of 1 × 106/g. ​These findings indicate a wide host range of K. septempunctata and further attention is required for its possible infections in fishes other than P. olivaceus.

Exploration and Characterization of Trichoderma sp. in Conventional and Organic Rice field in Bali

Abstract. Although Trichoderma spp has been widely used in the SRI technique of rice cultivation the sources of Trichoderma that can adapt well to the local environment have been an interesting issue for quite some time. It is commonly agreed that the local Trichoderma is much more preferred to be used for rice cultivation. In the present study, the Trichoderma from the soil of a rice field in Sukawati District, Bali where conventional fertilizer and pesticide has been applied for a very long time was isolated. After macroscopic observations (green color and sweet coconut smell ) the single isolated fungi have very much resembled Trichoderma Harzianum. 2 mL of the Trichoderma Harzianum solution was introduced in a plastic container containing 200 g half-boiled rice. After seven days the rice in the plastic appeared green. This sample will be used to produce more T. Harzianum for rice cultivation. One of the T.Harzianum treated rice hosts was coated with gold and subjected to SEM observation. Very high populated T. Harzianum fungi were observed. It was dominated by hyphae. No conidia and conidiophores were spotted. Instead, quite a high density of spherical and oval shape spores was observed. Such a high density of T.Harzianum will certainly meet the requirement for an efficient application in the cultivation field. It would also be interesting to see the interaction between such a highly populated T.Harzianum with other fungi or pathogens in understanding the role of Trichoderma as an antipathogen

Effects of Spore Density and Interaction With Heterodera glycines on Soybean Root Rot Caused by Fusarium solani and F. tricinctum.

Fusarium root rot, caused by Fusarium solani and F. tricinctum, is a major soybean disease in the North Central United States. This study investigated the effects of the macroconidia density and the additive effects of soybean cyst nematode (SCN), Heterodera glycines, on the severity of Fusarium root rot. To determine the effect of spore density on severity, experiments were conducted in La Prairie silt loam soil in a greenhouse using conidial suspensions ranging from 101 to 106 macroconidia/ml soil. Root discoloration and lesion lengths on taproots increased as spore numbers increased, with significant effects of spore densities starting at 104 and 105 macroconidia/ml soil for F. solani and F. tricinctum, respectively. A nonlinear sigmoid model was fitted to root discoloration against density, whereas a linear regression model was fitted to root lesion length against density. The interaction between the nematode at different egg densities with the two Fusarium spp. at 105 macroconidia/ml soil was investigated. In the greenhouse, root discoloration and lesion length were significantly greater in plants inoculated with Fusarium spp. and H. glycines at 10 eggs/ml soil or greater, compared with Fusarium spp. alone. In field trials, coinfestation of soil with the two Fusarium spp. and H. glycines significantly increased root rot severity at an egg density of 16.7 eggs/ml soil. The results indicated that the presence of SCN can increase severity of root rot caused by F. solani and F. tricinctum and egg density in the soil is an important factor in the interaction.

Spodoptera litura Fabr. Control Using Beauveria bassiana to Reduce Pest Damage Intensity and Maintain the Yield of Soybean

Soybean production has not been able to meet Indonesian needed. The production decreases every year due to the Spodoptera litura attack. The purpose of this study was to determine the effectiveness of Beauveria bassiana as a biological agent in controlling S.litura attacks in the field. The research was conducted at the Pest Laboratory of the Department of Agrotechnology, UIN Sunan Gunung Djati Bandung and in Cileunyi Bandung, West Java, from January to March 2017. The experiment used Completely Randomized Design (CRD) with eight B. bassiana spores density treatments with three replications. These treatments, i.e., negative control, positive control, 105, 106, 107, 108, 109, and 1010/ml aquadest applied to S. litura instar II larva. The post-hoc test used was Duncan’s Multiple Range Test of 5%. The results showed that the density of B. bassiana spores in 1010/ml aquadest caused mortality of S. litura larva at 76.67%. B. bassiana spores in 1010/ml aquadest was able to maintain the growth of soybean plants with pest damage intensity of 3.81%, maintained photosynthates to seeds with the value harvest index of 0.42 and the seed weight per plant reached 31.64 g. B. bassiana can be used as an entomopathogen in controlling attacks by Spodoptera litura.

The Effect of Mushrooms Trichoderma sp. and Its Secondary Metabolites on Suppression of Fusarium sp. and Growth of Tomato Plants (Solanum lycopersicum mill.)

<em>This study aims to determine the interaction effect of the type and dose of Trichoderma sp. and its secondary metabolites on suppression of Fusarium sp. wilt disease and its effect on the growth of tomato plants (Solanum lycopersicum mill.). This study used a Randomized Block Design (RBD) which consisted of two factors. The first factor is the type of application (J) which consists of three levels of treatment, namely: J1 = Trichoderma sp., J2 = Secondary metabolites. J3 = Trichoderma sp. + Secondary metabolites, while the second factor is the application dose (D) which consists of three treatment levels, namely: D1 = 10 ml/plant, D2 = 20 ml/plant, D3 = 30 ml/plant. The treatment was repeated 3 times to obtain 81 tomato plants and added 9 control treatment plants. The parameters observed were the percentage of wilt disease, plant height, stem diameter, number of leaflets, and number of branches. The results showed that in laboratory testing, the mushrooms Trichoderma sp. and secondary metabolites can inhibit the growth of the mushrooms Fusarium sp. In research in the field, treatment with Trichoderma sp., secondary metabolites, and Trichoderma sp. + secondary metabolites, with various spore densities and applied 7 days before planting can reduce the wilting percentage to 0%. The interaction treatment of type and application dose had a very significant effect on the number of leaflets, and had a significant effect on stem diameter but had no significant effect on plant height and number of branches. The highest results on the variable plant height and number of leaflets were found in the J3D3 treatment with a height of 82.67 cm and a number of leaflets of 85.11 strands. The highest results on the stem diameter variable were found in the J1D3 treatment with a diameter of 6.59 mm, while the variable number of branches was found in the J3D1 treatment with 1.35 branches.</em>

Application of wheat flour (Triticum aestivum) on spore density and sporulation efficiency of Bacillus megaterium isolated from Litopenaeus vannamei gastrointestinal tract

Abstract. Mahariawan IMD, Kusuma WE, Yuniarti A, Beltran MAG, Hariati AM. 2021. Application of wheat flour (Triticum aestivum) on spore density and sporulation efficiency of Bacillus megaterium isolated from Litopenaeus vannamei gastrointestinal tract. Biodiversitas 22: 3709-3715. Bacillus megaterium is frequently used in fish farming, such as white shrimp (Litopenaeus vannamei) pond, which can produce spores with high stability in its implementation. Currently, spore production still requires the availability of high-cost carbon sources. The objective of this research was to evaluate the effect of different wheat flour doses on spore density and sporulation efficiency of B. megaterium BM1. In flasks, 50 mL of each test medium was treated with different doses of wheat (10, 20, 30 and 40 g. L-1, respectively) and glucose was used as a control. Each treatment was inoculated with B. megaterium BM1 (2.6 x 108 CFU. mL-1) and incubated in a shaker incubator (120 rpm) at 37 °C for 120 hours. The results showed that the highest vegetative cell concentration (17 x 108 CFU. mL-1), growth rate (0.8 hour-1) and spore (14.7 x 108 spores. mL-1) were found in the wheat flour dose of 30 g. L-1. Furthermore, the highest sporulation efficiency was achieved at 20 g. L-1 of wheat (91.30%) and germination should be done at a dose less than 40 g. L-1. The size of the spores was 1.35-1.39 µm. Thus, 30 g. L-1 of wheat flour is a potential dose to produce spore for probiotic candidates.

Native arbuscular mycorrhizal fungi respond to rehabilitation in iron ore mining areas from the Eastern Brazilian Amazon

Rehabilitation of mining areas is a relevant and current subject, in which the response of microbial communities is an important evaluation tool regarding their progress. In this context, our study had the objective of evaluating the effect of rehabilitation on the community composition and activity of arbuscular mycorrhizal fungi, and their relation with main soil properties, in three iron ore mining sites from Serra Norte of Carajás in the Eastern Brazilian Amazon. For that, non-rehabilitated, rehabilitated, and reference areas within each site were evaluated for spore density and diversity, mycorrhizal colonization, glomalin contents, as well as soil chemical and physical attributes. In general, all mycorrhizal variables responded positively to the rehabilitation processes in the three mining sites. Over time, an increase of similarity of the mycorrhizal communities between rehabilitated and reference areas from each site was observed, as well as, a decrease of the easily extractable glomalin/total extractable glomalin ratio. High ratios of easily extractable glomalin/total extractable glomalin indicated high degree of disturbance and/or disequilibrium of ecosystems, whereas low ratios indicated their equilibrium and/or recovery. This relation can be an interesting parameter, easy to interpret and compare for assessing the degree of disturbance, equilibrium and/or recovery of environments, regardless of absolute values of these variables. Main soil properties related to mycorrhizal response were pH, texture, organic matter content, and cation exchange capacity. Briefly, our results showed the resilience of native mycorrhizal communities and the success of the rehabilitation actions carried out in this Amazonian region.

Formalin-casein enhances water absorbency of calcium alginate beads and activity of encapsulated Metarhizium brunneum and Saccharomyces cerevisiae

The control of root-feeding wireworms has become more challenging as synthetic soil insecticides have been progressively phased out due to environmental risk concerns. Innovative microbial control alternatives such as the so-called attract-and-kill strategy depend on the rapid and successful development of dried encapsulated microorganisms, which is initiated by rehydration. Casein is a functional additive that is already used in food or pharmaceutical industry due to its water binding capacity. Cross-linked forms such as formalin-casein (FC), exhibit altered network structures. To determine whether FC influences the rehydration of alginate beads in order to increase the efficacy of an attract-and-kill formulation for wireworm pest control, we incorporated either casein or FC in different alginate/starch formulations. We investigated the porous properties of alginate/starch beads and subsequently evaluated the activities of the encapsulated entomopathogenic fungus Metarhizium brunneum and the CO2 producing yeast Saccharomyces cerevisiae. Adding caseins altered the porous structure of beads. FC decreased the bead density from (1.0197 ± 0.0008) g/mL to (1.0144 ± 0.0008) g/mL and the pore diameter by 31%. In contrast to casein, FC enhanced the water absorbency of alginate/starch beads by 40%. Furthermore, incorporating FC quadrupled the spore density on beads containing M. brunneum and S. cerevisiae, and simultaneous venting increased the spore density even by a factor of 18. Moreover, FC increased the total CO2 produced by M. brunneum and S. cerevisiae by 29%. Thus, our findings suggest that rehydration is enhanced by larger capillaries, resulting in an increased water absorption capacity. Our data further suggest that gas exchange is improved by FC. Therefore, our results indicate that FC enhances the fungal activity of both fungi M. brunneum and S. cerevisiae, presumably leading to an enhanced attract-and-kill efficacy for pest control.Graphic abstract