Comparison of specific methane yield of perennial ryegrass prepared by thermal drying versus non-thermal drying in small-scale batch digestion tests.

Dried milled biomass samples are frequently utilised in small-scale batch digestion tests. However, herbage chemical composition can be altered by thermal drying, and this may affect specific methane (CH4) yields. Thus, the specific CH4 yield of herbage pre- and post-ensiling, prepared by two preparation methods were compared. Perennial ryegrass samples were either non-thermally dried (i.e. subject to cryogenic conditions, -196 °C) or thermally dried (40 °C), prior to milling. Specific CH4 yield was subsequently determined in a small-scale batch digestion test. Herbage pre-ensiling yielded 204 and 243 L CH4 kg(-1)VS(added) and herbage post-ensiling yielded 212 and 188 L CH4 kg(-1)VS(added) with non-thermal dried and thermal dried sample preparation methods, respectively. Due to opposing effects of thermal drying on CH4 yields of herbage either pre- or post-ensiling, it is not recommended to use thermal drying. Instead, it is recommended that non-thermal dried herbage samples are used in small-scale batch digestion tests.

Microbial community structure during fluoranthene degradation in the presence of plants.

AIMS: To investigate bacterial and fungal community structure during degradation of varying concentrations (0-5000 mg kg(-1) ) of the polycyclic aromatic hydrocarbon (PAH) fluoranthene in the presence or absence of tomato plants. METHOD AND RESULTS: Fluoranthene amended or unamended growing media, with or without a plant, were incubated in pots in a glasshouse for 30 days. Fluoranthene concentration was quantified using GC-FID, while bacterial and fungal community structure was investigated using trflp and arisa, respectively. The abundance of two ring hydroxylating dioxygenase genes was measured using qPCR. More fluoranthene was degraded in the presence of tomato plants at 500 and 5000 mg fluoranthene kg(-1) (P < 0·001), and it had a toxic effect on plant growth. Bacterial and fungal community composition in the rhizosphere was significantly different from that in nonrhizospheric and unplanted samples. The influence of fluoranthene on bacterial communities overcame that of the plant root such that community composition in rhizosphere and planted nonrhizospheric samples was broadly similar when fluoranthene was present. PAH-RHDα-GP genes were more abundant than PAH-RHDα-GN genes in all treatments. PAH-RHDα-GN abundance was unaffected by either PAH concentration or growing medium type, while the abundance of PAH-RHDα-GP was greatest in the rhizosphere. CONCLUSIONS: Plants promoted microbial growth and diversity and led to increases in abundance of Gram-positive dioxygenase genes, correlated with increased degradation of fluoranthene. SIGNIFICANCE AND IMPACT OF THE STUDY: This work contributes to knowledge in the broad area of biodegradation and also provides useful information for the design of future bioremediation strategies.

Changes in chemical composition and digestibility of three maize stover components digested by white-rot fungi.

Maize stover (total stem and leaves) is not considered a ruminant feed of high nutritive value. Therefore, an improvement in its digestibility may increase the viability of total forage maize production systems in marginal growth regions. The objective of this study was to describe the changes in chemical composition during the storage of contrasting components of maize stover (leaf, upper stem and lower stem) treated with either of two lignin degrading white-rot fungi (WRF; Pleurotus ostreatus, Trametes versicolor). Three components of maize stover (leaf, upper stem and lower stem), harvested at a conventional maturity for silage production, were digested with either of two WRF for one of four digestion durations (1-4 months). Samples taken prior to fungal inoculation were used to benchmark the changes that occurred. The degradation of acid detergent lignin was observed in all sample types digested with P. ostreatus; however, the loss of digestible substrate in all samples inoculated with P. ostreatus was high, and therefore, P. ostreatus-digested samples had a lower dry matter digestibility than samples prior to inoculation. Similarly, T. veriscolor-digested leaf underwent a non-selective degradation of the rumen-digestible components of fibre. The changes in chemical composition of leaf, upper stem and lower stem digested with either P. ostreatus or T. veriscolor were not beneficial to the feed value of the forage, and incurred high DM losses.

Conservation characteristics of corn ears and stover ensiled with the addition of Lactobacillus plantarum MTD-1, Lactobacillus plantarum 30114, or Lactobacillus buchneri 11A44.

The aim of this study was to investigate the effects of inoculating 3 contrasting lactic acid bacteria on the fermentation profile, estimated nutritive value, and aerobic stability of corn ears and stover produced under marginal growing conditions. Ears and stover were separated from whole-crop corn plants obtained from 3 replicate field blocks. Representative subsamples were precision chopped and allocated to 1 of the following treatments: an uninoculated control, Lactobacillus plantarum MTD-1 (LP1), L. plantarum 30114 (LP2), or Lactobacillus buchneri 11A44 (LB). Each bacterial additive was applied at a rate of 1 × 10(6) cfu/g of fresh herbage. Triplicate samples of each treatment were ensiled in laboratory silos at 15°C for 3, 10, 35, or 130 d. No difference was observed between the dry matter recoveries of uninoculated ear or stover silages and silages made with LP1, and the aerobic stability of uninoculated ear and stover silages did not differ from silages made with LB. Stover silages made with LP2 and ensiled for 35 d had a lower proportion of lactic acid in total fermentation products compared with LP1. The aerobic stability and dry matter recovery of ear and stover silages in this study were not improved when made with LB, LP1, or LP2, due to the indigenous highly heterolactic fermentation that prevailed in the uninoculated ear and stover during 130-d ensilage.

The effect of dietary concentrate and soya oil inclusion on microbial diversity in the rumen of cattle.

AIMS: Methane emissions from ruminants are a significant contributor to global greenhouse gas production. The aim of this study was to examine the effect of diet on microbial communities in the rumen of steers. METHODS AND RESULTS: The effects of dietary alteration (50 : 50 vs 90 : 10 concentrate-forage ratio, and inclusion of soya oil) on methanogenic and bacterial communities in the rumen of steers were examined using molecular fingerprinting techniques (T-RFLP and automated ribosomal intergenic spacer analysis) and real-time PCR. Bacterial diversity was greatly affected by diet, whereas methanogen diversity was not. However, methanogen abundance was significantly reduced (P = 0.009) in high concentrate-forage diets and in the presence of soya oil (6%). In a parallel study, reduced methane emissions were observed with these diets. CONCLUSIONS: The greater effect of dietary alteration on bacterial community in the rumen compared with the methanogen community may reflect the impact of substrate availability on the rumen bacterial community. This resulted in altered rumen volatile fatty acid profiles and had a downstream effect on methanogen abundance, but not diversity. SIGNIFICANCE AND IMPACT OF THE STUDY: Understanding how rumen microbial communities contribute to methane production and how these microbes are influenced by diet is essential for the rational design of methane mitigation strategies from livestock.

Assessing the impact of various ensilage factors on the fermentation of grass silage using conventional culture and bacterial community analysis techniques.

AIMS: Grass silage is an important ruminant feedstuff on farms during winter. The ensilage of grass involves a natural lactic acid bacterial fermentation under anaerobic conditions, and numerous factors can influence the outcome of preservation. The aim of this study was to investigate the effect of dry matter concentration, ensiling system, compaction and air infiltration on silage bacterial community composition. METHODS AND RESULTS: The impact of these factors was examined using conventional methods of microbial analysis and culture-independent Terminal Restriction Fragment Length Polymorphism (T-RFLP). Silage fermentation was restricted in herbage with a high dry matter concentration, and this was reflected in a shift in the bacterial population present. In contrast, ensiling system had little effect on bacterial community composition. Air infiltration, in the absence of compaction, altered silage bacterial community composition and silage pH. CONCLUSIONS: Dry matter concentration and the absence of compaction were the main factors affecting silage microbial community composition, and this was reflected in both the conventional culture-based and T-RFLP data. SIGNIFICANCE AND IMPACT OF THE STUDY: T-RFLP proved a useful tool to study the factors affecting ensilage. Apart from monitoring the presence or absence of members of the population, shifts in the relative presence of members could be monitored.

Bacterial community dynamics during the ensilage of wilted grass.

AIMS: Grass silage is the product formed by a natural lactic acid bacterial fermentation when grass is stored under anaerobic conditions, and represents an important ruminant feedstuff on farms during winter. Of the two commonly employed methods of ensiling forage, baled silage composition frequently differs from that of comparable precision-chop silage reflecting a different ensiling environment. The aim of this study was to investigate the dynamics of the silage fermentation in wilted grass and between ensiling systems. METHODS AND RESULTS: Fermentation dynamics were examined using traditional methods of silage analyses, including microbial enumeration and analysis of fermentation products, and culture-independent terminal restriction fragment length polymorphism (T-RFLP). A successful fermentation was achieved in both systems, with the fermentation (increase in lactic acid bacteria and lactic acid concentration, decrease in pH) proceeding rapidly once the herbage was ensiled. CONCLUSIONS: Under controlled conditions, little difference in silage quality and microbial composition were observed between ensiling systems and this was further reflected in the T-RFLP community analysis. SIGNIFICANCE AND IMPACT OF THE STUDY: T-RFLP proved a potentially useful tool to study the ensilage process and could provide valid support to traditional methods, or a viable alternative to these methods, for investigating the dynamics of the bacterial community over the course of the fermentation.

Histological grading of epithelial ovarian carcinomas.

The grade of an ovarian epithelial neoplasm provides useful information. However, different approaches to grading exist and many ovarian cancers are not graded. We examined primary ovarian cancers from patients treated at our hospital and applied the 'universal' grading system. We found a significant association between grade and clinical stage, with a survival difference between grades for low-stage tumours. The application of grade is discussed in the light of developments in the grading of other gynaecological cancers.

Radial scars/complex sclerosing lesions and malignancy in a screening programme: incidence and histological features revisited.

AIMS: Radial scars (RS) are benign entities, frequently identified on screening mammography, which may be associated with malignancy. Much debate has been generated with regard to the optimum management of RS. We present our experience of RS in the first 5 years of a screening programme. The aim was to evaluate (i) the incidence of atypia and malignancy and (ii) the value of the preoperative core biopsy. We also further characterize the histological features. METHODS AND RESULTS: One hundred and twenty-five histologically confirmed cases of RS were reviewed (111 had preoperative biopsies). Thirty-one (24.8%) patients had a final malignant diagnosis (11 with invasive malignancy) and 28 (22.4%) showed atypia (including lobular carcinoma in situ). In those with core biopsies and a final malignant diagnosis, 12 cases were categorized as B5 (41.3%), three as B4 (10.3%), 12 as B3 (41.3%) and two as B2 (7%). Common histological features included obliterated ducts and chronic inflammation with, less frequently, neural hyperplasia (16.8%) and perineural invasion (3.2%). CONCLUSIONS: The high incidence of atypia and malignancy identified in our study justifies our policy of removing all mammographically detected RS. We emphasize the utility of preoperative core biopsy evaluation in permitting one-stage surgical therapy in those with B5 diagnoses.

Microbial community changes during the bioremediation of creosote-contaminated soil.

AIMS: To investigate the effects of aeration on the ex situ biodegradation of polycyclic aromatic hydrocarbons (PAHs) in creosote-contaminated soil and its effect on the microbial community present. METHODS AND RESULTS: Aerated and nonaerated microcosms of soil excavated from a former timber treatment yard were maintained and sampled for PAH concentration and microbial community changes by terminal restriction fragment length polymorphism (TRFLP) analysis. After an experimental period of just 13 days, degradation was observed with all the PAHs monitored. Abiotic controls showed no loss of PAH. Results unexpectedly showed greater loss of the higher molecular weight PAHs in the nonaerated control. This may have been due to the soil excavation causing initial decompaction and aeration and the resulting changes caused in the microbial community composition, indicated by TRFLP analysis showing several ribotypes greatly increasing in relative abundance. Similar changes in both microcosms were observed but with several possible key differences. The species of micro-organisms putatively identified included Bacilli, pseudomonad, aeromonad, Vibrio and Clostridia species. CONCLUSIONS: Excavation of the contaminated soil leads to decompaction, aeration and increased nutrient availability, which in turn allow microbial biodegradation of the PAHs and a change in the microbial community structure. SIGNIFICANCE AND IMPACT OF THE STUDY: Understanding the changes occurring in the microbial community during biodegradation of all PAHs is essential for the development of improved site remediation protocols. TRFLP allows useful monitoring of the total microbial community.