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Five arthroconidium-producing yeast strains representing a novel Trichosporon-like species were independently isolated from the UK, Hungary and Norway. Two strains (Bio4T and Bio21) were isolated from biogas reactors used for processing grass silage, with a third strain (S8) was isolated from soil collected at the same UK site. Two additional strains were isolated in mainland Europe, one from soil in Norway (NCAIM Y.02175) and the other from sewage in Hungary (NCAIM Y.02176). Sequence analyses of the D1/D2 domains of the LSU rRNA gene and internal transcribed spacer (ITS) region indicated that the novel species belongs to the recently reinstated genus Apiotrichum and is most closely related to Apiotrichum scarabaeorum, a beetle-associated species first found in South Africa. Despite having similar physiological characteristics, the two species can be readily distinguished from one another by ITS sequencing. The species name Apiotrichum terrigenum sp. nov. is proposed to accommodate these strains, with Bio4T (=CBS 11373T=NCYC 3540T) designated as the type strain. The Mycobank deposit number is MB817431.

Xylitol is a low calorie sweetener that can be produced through a bioconversion approach from lignocellulosic biomass that requires pre-treatment prior to the bioconversion of xylose to xylitol. Steam explosion (SE) is an industrially scalable pre-treatment (PT) process with the potential to liberate xylose monomers, however SE-PT has not been optimized for xylose release from multiple feedstock. The effect of pressure, substrate weight, phosphoric acid loading concentration and residence time on four feedstock [wheat straw (WS), corn stover (CS), Miscanthus (M), and willow (W)] for xylose release and minimal fermentation inhibitor production [furfural and 5-hydroxymethylfurfural (HMF)] was investigated using the Taguchi methodology for design of experiment (DoE) with variation at four levels (44). An L16 orthogonal array design was utilized and all factors indicated influence on xylose release and inhibitor formation and the resulting xylose rich hydrolysate assessed for bioconversion to xylitol. The L16 DoE gave hydrolysates containing 75–95% of xylose content in the original biomass, whilst retaining cellulose and lignin components in the fiber. The level of inhibitors were within boundary limits to enable microbial fermentation of the hydrolysates to xylitol. Fine tuning of the overall evaluation criteria (OEC) model imbibing 1.5 kg feedstock in 1.2% w/v orthophosphoric acid, 12 bar(g) and 6 min residence time resulted in 90% xylose recovery and production of >1,000 L of wheat straw hydrolysate for bioconversion to xylitol. The advantages and limitations of the Taguchi OEC model and further improvements to this process are discussed in a biorefining context.

Efficient utilization of lignocellulosic biomass requires pretreatment in order to liberate cellulose from lignin and disrupt its recalcitrant crystalline structure before effective enzymatic hydrolysis can take place. Three different pretreatment methods (pressure cooking with dilute alkali and dilute acid as well as alkaline extraction) to recover the xylooligosaccharides fraction from five different grass silage samples, whole crop rye silage and maize silage were compared. The predominant end products released were xylobiose, xylotetraose, xylopentaose and xylohexaose whereas the xylooligosaccharides release pattern differed with the substrate. Maximum values of xylooligosaccharides was found for grass silage 17.26 g/L, whole crop rye silage 3.06 g/L and for maize silage 5.77 g/L. Results reveal the production of high value by-products from agricultural biomass. Advantages of the green-biorefinery concept include a resulting liquid fraction after pretreatment with very low contents of inhibitors such ...

To keep the concept of a safe food supply to the consumers, animal feed industries world over are showing an increasing interest in the direct-fed microbials (DFM) for improved animal performance in terms of growth or productivity. This becomes all the more essential in a situation, where a number of the residues of antibiotics and/or other growth stimulants reach in milk and meat with a number of associated potential risks for the consumers. Hence, in the absence of growth stimulants, a positive manipulation of the rumen microbial ecosystem to enhance the feedstuff utilization for improved production efficiency by ruminants has become of much interest to the researchers and entrepreneurs. A few genera of live microbes (i.e., bacteria, fungi and yeasts in different types of formulations from paste to powder) are infrequently used as DFM for the domestic ruminants. These DFM products are live microbial feed supplements containing naturally occurring microbes in the rumen. Among different DFM possibilities, anaerobic rumen fungi (ARF) based additives have been found to improve ruminant productivity consistently during feeding trials. Administration of ARF during the few trials conducted, led to the increased weight gain, milk production, and total tract digestibility of feed components in ruminants. Anaerobic fungi in the rumen display very strong cell-wall degrading cellulolytic and xylanolytic activities through rhizoid development, resulting in the physical disruption of feed structure paving the way for bacterial action. Significant improvements in the fiber digestibility were found to coincide with increases in ARF in the rumen indicating their role. Most of the researches based on DFM have indicated a positive response in nutrient digestion and methane reducing potential during in vivo and/or in vitro supplementation of ARF as DFM. Therefore, DFM especially ARF will gain popularity but it is necessary that all the strains are thoroughly studied for their beneficial properties to have a confirmed ‘generally regarded as safe’ status for ruminants.

Agriculture significantly contributes to global greenhouse gas (GHG) emissions and there is a need to develop effective mitigation strategies. The efficacy of methods to reduce GHG fluxes from agricultural soils can be affected by a range of interacting management and environmental factors. Uniquely, we used the Taguchi experimental design methodology to rank the relative importance of six factors known to affect the emission of GHG from soil: nitrate (NO3-) addition, carbon quality (labile and non-labile C), soil temperature, water-filled pore space (WFPS) and extent of soil compaction. Grassland soil was incubated in jars where selected factors, considered at two or three amounts within the experimental range, were combined in an orthogonal array to determine the importance and interactions between factors with a L16 design, comprising 16 experimental units. Within this L16 design, 216 combinations of the full factorial experimental design were represented. Headspace nitrous oxide (N2O), methane (CH4) and carbon dioxide (CO2) concentrations were measured and used to calculate fluxes. Results found for the relative influence of factors (WFPS and NO3- addition were the main factors affecting N2O fluxes, whilst glucose, NO3- and soil temperature were the main factors affecting CO2 and CH4 fluxes) were consistent with those already well documented. Interactions between factors were also studied and results showed that factors with little individual influence became more influential in combination. The proposed methodology offers new possibilities for GHG researchers to study interactions between influential factors and address the optimized sets of conditions to reduce GHG emissions in agro-ecosystems, while reducing the number of experimental units required compared with conventional experimental procedures that adjust one variable at a time.

Five yeast morphotypes were isolated from biogas reactors at North Wyke Research, Okehampton, UK. Out of the five morphotypes, four were identified as known species. In contrast, the fifth morphotype strain, Bio10(T), was found to differ from Bullera dendrophila and Kwoniella mangroviensis, its closest phylogenetic neighbours, by 2.6-2.9% with respect to the nucleotide sequence of the D1/D2 domain of the 26S rRNA gene and by 5.6-6.2% with respect to the internal transcribed spacer 1 (ITS1)-5.8S rRNA gene-ITS2 region. Bio10(T) also differs from these two species by a number of phenotypic characteristics. Thus, based on the phenotypic differences and phylogenetic analysis, strain Bio10(T) is assigned the status of a new species of Cryptococcus, for which the name Cryptococcus shivajii sp. nov. is proposed. The type strain is Bio10(T) (NCYC 3541(T) = CBS 11374(T)).

Predicted increases in greenhouse gas emissions, depleting fossil fuel supplies, global conflicts, and energy security are major factors driving the search for renewable energy supplies. Based on future energy demand projections, biofuels production is expected to increase. However, this increase represents a small fraction of this growing demand because the land area required to grow sufficient biofuels crops is unavailable. Hence, fulfilling the growing energy demand after attaining peak fossil fuel production will include using a combination of energy sources such as renewables, wind, geothermal, nuclear, hydroelectric, solar, and coal. Current and potential feedstocks include grains, grasses, root crops, oil seeds, algae, and lignocellulosics. Grains, sugar crops, and lignocellulosics are the main feedstocks used in full-scale first- and second-generation ethanol processes. While first-generation biodiesel is produced mainly from corn, soybeans, canola oil, rapeseed, palm oil, Jatropha, and coconut oil, second-generation fuels are produced from lignocellulosics. Third-generation technology employs several processes to produce a variety of biofuels from algae while fourth-generation technologies, a developing concept, is intended to employ genetically modified terrestrial or aquatic plants. In another concept, fourth-generation technologies can be configured with CO2 sequestration and storage. First-generation biobutanol is produced from corn or molasses and from sugar beet as well as sugarcane, while second-generation production processes utilize lignocellulosics such as corn stover, rice straw, corn fiber, switchgrass, alfalfa, reed canary grass, sugarcane bagasse, Miscanthus, waste paper, dry distillers grain with solubles (DDGS), and soy molasses. A variety of technologies, based on the enzyme systems, are currently under investigation for producing biohydrogen. Biohydrogen production routes are divided into biophotolysis (direct/indirect), dark fermentation, and photofermentation. Increasing global demand is expected to drive increasing bioethanol and biobutanol production using food and nonfood feedstocks. At the same time, researchers are developing technologies to produce biohydrogen and biodiesel. Biohydrogen and biodiesel production technologies are in their developmental stages; however, with innovation, these technologies are expected to mature into economical processes.

Two euryarchaeota-specific 16S rRNA gene clone libraries (MT1 and MT2) and two bacterial 16S rRNA gene clone libraries (HW1 and HW2) were constructed using DNA isolated from two sludge samples (sample 1 and sample 2) collected from two separate tanks of commercial biogas plant operating at the methanogenesis stage, each receiving the same feedstock, after heat pretreatment for an hour at 70 °C, located near Holsworthy, Devon, UK. In the euryarchaeotal-based libraries, both samples revealed clone sequenses assigned to Methanomicrobiales and Methanosarcinales of the phylum Euryarchaeota. Although not much difference was observed in the Archaeal diversity, phylogenetic tree analysis demonstrates that 25 % of clone sequences of sample 1 and 42 % of clone sequences of sample 2 formed separate clades from cultured diversity. 16S rRNA gene-based bacterial libraries also revealed the ubiquitous presence of phyla Firmicutes and Proteobacteria. Cellulolytic bacterial clone sequences were abundant in both the samples. Fluorescent in situ hybridisation (FISH) results also revealed the presence of Methanomicrobiales and Methanosarcinales as a dominant group.

The growing demand for sustainable animal production is compelling researchers to explore the potential approaches to reduce emissions of greenhouse gases from livestock that are mainly produced by enteric fermentation. Some potential solutions, for instance, the use of chemical inhibitors to reduce methanogenesis, are not feasible in routine use due to their toxicity to ruminants, inhibition of efficient rumen function or other transitory effects. Strategies, such as use of plant secondary metabolites and dietary manipulations have emerged to reduce the methane emission, but these still require extensive research before these can be recommended and deployed in the livestock industry sector. Furthermore, immunization vaccines for methanogens and phages are also under investigation for mitigation of enteric methanogenesis. The increasing knowledge of methanogenic diversity in rumen, DNA sequencing technologies and bioinformatics have paved the way for chemogenomic strategies by targeting methane producers. Chemogenomics will help in finding target enzymes and proteins, which will further assist in the screening of natural as well chemical inhibitors. The construction of a methanogenic gene catalogue through these approaches is an attainable objective. This will lead to understand the microbiome function, its relation with the host and feeds, and therefore, will form the basis of practically viable and eco-friendly methane mitigation approaches, while improving the ruminant productivity.

Agriculture significantly contributes to global greenhouse gas (GHG) emissions and there is a need to develop effective mitigation strategies. The efficacy of methods to reduce GHG fluxes from agricultural soils can be affected by a range of interacting management and environmental factors. Uniquely, we used the Taguchi experimental design methodology to rank the relative importance of six factors known to affect the emission of GHG from soil: nitrate (NO3−) addition, carbon quality (labile and non-labile C), soil temperature, water-filled pore space (WFPS) and extent of soil compaction. Grassland soil was incubated in jars where selected factors, considered at two or three amounts within the experimental range, were combined in an orthogonal array to determine the importance and interactions between factors with a L16 design, comprising 16 experimental units. Within this L16 design, 216 combinations of the full factorial experimental design were represented. Headspace nitrous oxide (N2O), methane (CH4) and carbon dioxide (CO2) concentrations were measured and used to calculate fluxes. Results found for the relative influence of factors (WFPS and NO3− addition were the main factors affecting N2O fluxes, whilst glucose, NO3− and soil temperature were the main factors affecting CO2 and CH4 fluxes) were consistent with those already well documented. Interactions between factors were also studied and results showed that factors with little individual influence became more influential in combination. The proposed methodology offers new possibilities for GHG researchers to study interactions between influential factors and address the optimized sets of conditions to reduce GHG emissions in agro-ecosystems, while reducing the number of experimental units required compared with conventional experimental procedures that adjust one variable at a time.

Laccase production by Coriolopsis caperata RCK2011 under solid state fermentation was optimized following Taguchi design of experiment. An orthogonal array layout of L18 (2(1) × 3(7)) was constructed using Qualitek-4 software with eight most influensive factors on laccase production. At individual level pH contributed higher influence, whereas, corn steep liquor (CSL) accounted for more than 50% of the severity index with biotin and KH2PO4 at the interactive level. The optimum conditions derived were; temperature 30°C, pH 5.0, wheat bran 5.0 g, inoculum size 0.5 ml (fungal cell mass = 0.015 g dry wt.), biotin 0.5% w/v, KH2PO4 0.013% w/v, CSL 0.1% v/v and 0.5 mM xylidine as an inducer. The validation experiments using optimized conditions confirmed an improvement in enzyme production by 58.01%. The laccase production to the level of 1623.55 Ugds(-1) indicates that the fungus C. caperata RCK2011 has the commercial potential for laccase.

The interest in xylitol has increased considerably in recent years, due to many commercial applications in different industrial sectors like food, dental related products, and pharmaceuticals. As industrial biotechnological routes to xylitol are costly they currently represents a small fraction of the marketshare. Therefore, over the past few decades much effort has been devoted to the development of cost-effective and environmentally-friendly biotechnological processes by evaluating cheaper lignocellulosic substrates. In this chapter, xylitol commercial processes, cost and market trends are discussed with a special focus on biorefining and biotechnological methods. Increasing commercial and scientific interest in xylitol has led to a strong demand for this product in the global market, of more than 125,000 tons per anum, with a value that is relatively high (4.5–5.5$/kg for bulk purchase by pharma/chewing gum companies and 12£ or 20$/kg in supermarkets) makes its an attractive proposition for commercialization.

Maximizing methane production while maintaining an appreciable level of process stability is a crucial challenge in the anaerobic digestion industry. In this study, the role of six parameters: the type of immobilizing supports, loading rate, inoculum levels, C:N ratio, trace nutrients concentrations and mixing rate, on methane production were investigated under thermophilic conditions (55 ± 1 °C) with synthetic substrate medium. The immobilizing supports were Silica gel, Sand, Molecular Sieve and Dowex Marathon beads. A Taguchi Design of Experiment (DOE) methodology was employed to determine the effects of different parameters using an L 16 orthogonal array. Overall, immobilizing supports influenced methane production substantially (contributing 61.3% of the observed variation in methane yield) followed by loading rate and inoculum which had comparable influence (17.9% and 17.7% respectively). Optimization improved methane production by 153% (from 183 to 463 ml CH 4 l −1 d −1 ).

A yeast-like fungus producing a large amount of extracellular polysaccharide was isolated from the biogas reactors at North Wyke Research, UK (latitude, 50°46′29″N; longitude, 3°55′23″W). This strain was identified as Aureobasidium pullulans based on nucleotide sequence of the D1/D2 domain of the large-subunit (LSU) rRNA gene. Extracellular polysaccharide or pullulan, produced from this new strain of A. pullulans in shake flasks and a stirred tank fermenter was investigated. A maximum polysaccharide concentration of 40.1 g l −1 , and productivity of 12.5 g l −1 per day was obtained in a batch culture from stirred tank fermenter. The optimal cultivation conditions for pullulan production for this strain in 250 ml shake flask containing 100 ml of sucrose medium were observed at 28 °C and with 200 rpm. The effect of different sugars and nitrogen sources on pullulan production was investigated. It was found that more pullulan was produced when the strain was grown in the medium supplemented with NaNO 3 than when it was cultivated in the medium supplemented with C5 and C6 sugars and other nitrogen sources.