Co-cultured methanogen improved the metabolism in the hydrogenosome of anaerobic fungus as revealed by gas chromatography-mass spectrometry analysis

Methane production and lignocellulosic degradation of wastes from rice, corn and sugarcane by natural anaerobic fungi-methanogens co-culture

Biomass from agriculture, forestry, and urban wastes is a potential renewable organic resource for energy generation. Many investigations have demonstrated that anaerobic fungi and methanogens could be co-cultured to degrade lignocellulose for methane generation. Thus, this study aimed to evaluate the effect of natural anaerobic fungi-methanogens co-culture on the methane production and lignocellulosic degradation of wastes from rice, corn and sugarcane. Hu sheep rumen digesta was used to develop a natural anaerobic fungi-methanogen co-culture. The substrates were rice straw (RS), rich husk (RH), corn stover (CS), corn cobs (CC), and sugarcane baggage (SB). Production of total gas and methane, metabolization rate of reducing sugar, glucose, and xylose, digestibility of hemicellulose and cellulose, activity of carboxymethylcellulase and xylanase, and concentrations of total acid and acetate were highest (P < 0.05) in CC, moderate (P < 0.05) in RS and CS, and lowest (P < 0.05) in SB and RH. The pH, lactate and ethanol were lowest (P < 0.05) in CC, moderate (P < 0.05) in RS and CS, and lowest (P < 0.05) SB and RH. Formate was lowest (P < 0.05) in CC, RS and CS, moderate (P < 0.05) in SB, and lowest (P < 0.05) in RH. Therefore, this study indicated that the potential of methane production and lignocellulosic degradation by natural anaerobic fungi-methanogens co-culture were highest in CC, moderate in RS and CS, and lowest in SB and RH.

Bioactivity Screening and Chemical Characterization of Biocompound from Endophytic Neofusicoccum parvum and Buergenerula spartinae Isolated from Mangrove Ecosystem

The discovery of biomolecules has been the subject of extensive research for several years due to their potential to combat harmful pathogens that can lead to environmental contamination and infections in both humans and animals. This study aimed to identify the chemical profile of endophytic fungi, namely Neofusicoccum parvum and Buergenerula spartinae, which were isolated from Avecinnia schaueriana and Laguncularia racemosa. We identified several HPLC-MS compounds, including Ethylidene-3,39-biplumbagin, Pestauvicolactone A, Phenylalanine, 2-Isopropylmalic acid, Fusaproliferin, Sespendole, Ansellone, Calanone derivative, Terpestacin, and others. Solid-state fermentation was conducted for 14-21 days, and methanol and dichloromethane extraction were performed to obtain a crude extract. The results of our cytotoxicity assay revealed a CC₅₀ value > 500 μg/mL, while the virucide, Trypanosoma, leishmania, and yeast assay demonstrated no inhibition. Nevertheless, the bacteriostatic assay showed a 98% reduction in Listeria monocytogenes and Escherichia coli. Our findings suggest that these endophytic fungi species with distinct chemical profiles represent a promising niche for further exploring new biomolecules.

No time to die: Comparative study on preservation protocols for anaerobic fungi

Anaerobic fungi (AF, phylum Neocallimastigomycota) are best known for their ability to anaerobically degrade recalcitrant lignocellulosic biomass through mechanic and enzymatic means. While their biotechnological potential is well-recognized, applied research on AF is still hampered by the time-consuming and cost-intensive laboratory routines required to isolate, maintain, and preserve AF cultures. Reliable long-term preservation of specific AF strains would aid basic as well as applied research, but commonly used laboratory protocols for AF preservation can show erratic survival rates and usually exhibit only moderate resuscitation success for up to one or two years after preservation. To address both, the variability, and the preservation issues, we have set up a cross-laboratory, year-long study. We tested five different protocols for the preservation of AF. The experiments were performed at three different laboratories (Austria, Germany, Switzerland) with the same three morphologically distinct AF isolates (Anaeromyces mucronatus, Caeocmyces sp., and Neocallimastix cameroonii) living in stable co-culture with their naturally occurring, syntrophic methanogens. We could show that handling greatly contributes to the variability of results, especially in Anaeromyces mucronatus. Cryopreservation of (mature) biomass in liquid nitrogen had the highest overall survival rates (85-100%, depending on the strain and laboratory). Additionally, preservation on agar at 39°C had surprisingly high survival rates for up to 9 months, if pieces of agar containing mature AF thalli were resuscitated. This low-cost, low-effort method could replace consecutive batch cultivation for periods of up to 6 months, while long-term preservation is best done by cryopreservation in liquid nitrogen. Regardless of the method, however, preserving several replicates (>three) of the same strain is highly advisable.

Roughage biodegradation by natural co-cultures of rumen fungi and methanogens from Qinghai yaks

Anaerobic fungus–methanogen co-cultures from rumen liquids and faeces can degrade lignocellulose efficiently. In this study, 31 fungus–methanogen co-cultures were first obtained from the rumen of yaks grazing in Qinghai Province, China, using the Hungate roll-tube technique. The fungi were identified according to morphological characteristics and internal transcribed spacer (ITS) sequences. The methanogens associated with each fungus were identified by polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE) and 16S rRNA gene sequencing. They were five co-culture types: Neocallimastix frontalis + Methanobrevibacter ruminantium, Neocallimastix frontalis + Methanobrevibacter gottschalkii, Orpinomyces joyonii + Methanobrevibacter ruminantium, Caecomyces communis + Methanobrevibacter ruminantium, and Caecomyces communis + Methanobrevibacter millerae. Among the 31 co-cultures, during the 5-day incubation, the N. frontalis + M. gottschalkii co-culture YakQH5 degraded 59.0%–68.1% of the dry matter (DM) and 49.5%–59.7% of the neutral detergent fiber (NDF) of wheat straw, corn stalk, rice straw, oat straw and sorghum straw to produce CH₄ (3.0–4.6 mmol/g DM) and acetate (7.3–8.6 mmol/g DM) as end-products. Ferulic acid (FA) released at 4.8 mg/g DM on corn stalk and p-coumaric acid (PCA) released at 11.7 mg/g DM on sorghum straw showed the highest values, with the following peak values of enzyme activities: xylanase at 12,910 mU/mL on wheat straw, ferulic acid esterase (FAE) at 10.5 mU/mL on corn stalk, and p-coumaric acid esterase (CAE) at 20.5 mU/mL on sorghum straw. The N. frontalis + M. gottschalkii co-culture YakQH5 from Qinghai yaks represents a new efficient combination for lignocellulose biodegradation, performing better than previously reported fungus–methanogen co-cultures from the digestive tract of ruminants.

Co-culturing fungus Penicillium citrinum and strain Citrobacter freundii improved nitrate removal and carbon utilization by promoting glyceride metabolism

Exploring the interaction between denitrifying microbial species is significant for improving denitrification performance. In this study, the effects of co-culturing fungus Penicillium citrinum and strain Citrobacter freundii on denitrification were investigated. Results showed that the maximum nitrate removal and carbon utilization in co-culture were 68.0 and 14.1 mg·L^-1·d^-1, respectively. The total adenosine triphosphatase activity was increased to 9.87 U‧mg^-1 protein in co-culture, and nicotinamide adenine dinucleotide production was 1.7-2.3 times that of monoculture, attributing to increased carbon utilization. Further metabolomics and membrane permeability assay revealed that co-culture increased the metabolism of glycerides, thereby enhancing the membrane permeability of strain Citrobacter freundii and promoting the transmembrane transport of nitrate and glucose, which boosted nitrate reductase activity and nicotinamide adenine dinucleotide production in turn. In summary, co-culturing promoted carbon utilization and enhanced substrate removal efficiency through the metabolism of glycerides, which provided a strategy to enhance denitrification performance in wastewater treatment.

Microbial communities and their enzymes facilitate degradation of recalcitrant polymers in anaerobic digestion

Microbial consortia efficiently degrade complex biopolymers found in the organic fraction of municipal solid waste (OFMSW). Through enzyme production and division of labor during anaerobic digestion, microbial communities break down recalcitrant polymers and make fermentation products, including methane. However, microbial communities remain underutilized for waste degradation as it remains difficult to characterize and predict microbial interactions during waste breakdown, especially as cultivation conditions change drastically throughout anaerobic digestion. This review discusses recent progress and opportunities in cultivating natural and engineered consortia for OFMSW hydrolysis, including how recalcitrant substrates are degraded by enzymes as well as the critical factors that govern microbial interactions and culture stability. Methods to measure substrate degradation are also reviewed, and we demonstrate the need for increased standardization to enable comparisons across different environments.

Effects of Olive (Olea europaea L.) Leaves with Antioxidant and Antimicrobial Activities on In Vitro Ruminal Fermentation and Methane Emission

Simple Summary

Olives are cultivated mostly in the Mediterranean as well as in Asia Minor, Korea, Japan, and China. Olive oil is currently used as a food ingredient in human diet, and its consumption is gradually expanding in various countries. Therefore, olive cultivation and oil extraction produce a significant amount of byproducts; providing these byproducts as feed to livestock has been attempted for a long period. Economic, environmental, and nutritional considerations make the use of olive byproducts efficient and cost-effective as feed for ruminants. Among the olive byproducts, olive leaves (OLs) contain higher levels of polyphenols than olive fruits, and have a very high feed value. In this study, it was confirmed that methane production decreased during 12 h of in vitro fermentation, and the number of fat-utilizing microorganisms increased in the 5% OLs group. OLs were found to show antioxidant and antimicrobial activity. Moreover, the proportion of cellulose-degrading bacteria, Fibrobacter succinogenes, Ruminococcus albus, and Ruminococcus flavefaciens increased in the 5% OLs group at 12 h and decreased at 24 h. Olive leaves are believed to be very useful as feed additives and supplements for ruminants.

Abstract

We evaluated whether olive leaves (OLs) are effective as feed additives and supplements for ruminants and the potential methane reduction effects during in vitro fermentation. Two Hanwoo cows (460 ± 20 kg) equipped with cannula were fed Timothy hay and corn-based feed 3% of the body weight at a ratio of 6:4 (8:30 a.m. and 5:00 p.m.). Ruminal fluid from the cows was collected and mixed before morning feeding. In vitro batch fermentation was monitored after 12 and 24 h of incubation at 39 °C, and OLs were used as supplements to achieve the concentration of 5% in the basal diet. At 12 h of fermentation, methane production decreased in the 5% OLs group compared to that in the control group, but not at 24 h. The proportion of cellulose-degrading bacteria, Fibrobacter succinogenes, Ruminococcus albus, and Ruminococcus flavefaciens, tended to increase in the 5% OLs group at 12 h. The amount of ammonia produced was the same as the polymerase chain reaction result for Prevotella ruminicola. At 12 h, the proportion of Prevotella ruminicola was significantly higher in the 5% OLs group. OLs may be used incorporated with protein byproducts or other methane-reducing agents in animal feed.