Relative fibrolytic activities of anaerobic rumen fungi on untreated and sodium hydroxide treated barley straw in in vitro culture

The Effects of Animal, Collection Time, and Interval on the Microbiota Structure, Metabolism, and Degradative Potential of Rumen Fluid Inoculum Collected by Esophageal Probe from Hay-Fed Cows

Rumen fluid (RF) is the greatest source of uncontrolled inter-assay variations in in vitro digestibility tests. This study aimed to investigate the effect of donor cow (DC) individual variability, time relative to feeding, and weekly sampling intervals on RF microbiota structure and metabolism, and on its degradative capacity expressed as enzymatic activity (EA). RF was collected using an esophageal probe from 4 Holstein hay-fed DCs before feeding, and 4 and 8 h post-feeding, over 3 days with one-week intervals, for a total of 3 weeks. Rumen bacteriome ß-diversity was affected by DCs and the one-week interval but not by time relative to feeding. However, volatile fatty acids and NDF and DM digestibility were not altered based on DCs. Propionic, lactic, and butyric acids were consistent between weeks, with some variations in lactic and butyric acids 8 h after feeding. Amylase and cellulase activities fluctuated between the weekly intervals, while xylanase activity increased in RF collected at 4 and 8 h after feeding (p = 0.030) and in DC3 compared to the other DCs (p < 0.001). Our results reinforce the importance of pooling RF from multiple cows and increasing the number of replicates to enhance the accuracy of the analysis.

Characteristics of a recombinant Fusarium verticillioides cutinase and its effects on enzymatic hydrolysis of rice straw

The current study heterologously expressed a cutinase from Fusarium verticillioides by Pichia pastoris and investigated its properties and effects on the hydrolysis of rice straw. The optimal pH and temperature for F. verticillioides cutinase were 8.0 and 50 °C, respectively. F. verticillioides cutinase had poor thermal stability and could be inhibited by some metal ions, inhibitors, and detergents (5 mM), including Ni²⁺, Zn²⁺, Cu²⁺, Ca²⁺, Mn²⁺, sodium dodecyl sulfate, EDTA, and Tween-20. F. verticillioides cutinase could tolerate 15% methanol and dimethyl sulfoxide but was significantly repressed by 15% ethanol and acetone with 48% and 63% residual activity, respectively. F. verticillioides cutinase could degrade the cuticle of rice straw with palmitic acid and stearic acid as the main products. However, the dissolving sugars released from the rice straw treated with F. verticillioides cutinase were significantly reduced by 29.2 μg/mL compared with the control (107.9 μg/mL). Similarly, the reducing sugars produced from the cellulase hydrolysis of rice straw pretreated with F. verticillioides cutinase were reduced by 63.5 μg/mL relative to the control (253.6 μg/mL). Scanning electron microscopy results showed that numerous tuberculate or warty protrusions were present nearly everywhere on the surface of rice straw treated with F. verticillioides cutinase, and some protrusions even covered and blocked the stomata of the rice straw surface. Current limited data indicate that F. verticillioides cutinase might not be an appropriate choice for improving the utilization of agricultural straws.

Replacement of alfalfa hay (Medicago sativa L.) with subabul (Leucaena leucocephala) leaf meal in diets of Najdi goats: effect on digestion activity of rumen microorganisms

This study investigated the effect of replacing alfalfa hay by subabul leaf meal (SLM) on digestion, fermentation parameters and rumen bacteria and fungi activity of Najdi goats. Six Najdi goats (150 ± 15 days of age and initial body weight of 35 ± 1.1 kg) were randomly assigned to one of two dietary treatments in a balanced completely randomized design (three goats per treatment) for 56 days. Experimental treatments included alfalfa hay as control group and diet containing SLM (SLM replacing alfalfa hay at 50% level). Bacterial and fungi activity and rumen fermentation parameters of animals fed experimental diets were determined. Dry matter disappearance (DMD) was unaffected by replacing SLM with alfalfa hay for both rumen bacteria and fungi in different incubation times, except for 48 h of incubation in specific culture medium of mixed rumen bacteria, which decreased for SLM group (P > 0.05). NDF disappearance (NDFD) and ADF disappearance (ADFD) after 24 and 48 h of incubation in specific culture medium of mixed rumen bacteria was not affected by experimental diets (P > 0.05). However, 72 h after incubation, NDFD in SLM treatment decreased (P > 0.05). Gas production parameters of rumen bacteria were similar for both experimental diets, but partitioning factor (PF), efficiency microbial biomass production (EMBP), microbial protein production (MP), and organic matter truly digested (OMTD) decreased (p < 0.05) in specific culture medium of mixed rumen fungi for SLM diet. There was significant decrease in total protozoa population for diet containing SLM (p < 0.05). Results indicated that replacement of alfalfa hay by SLM had no major effect on rumen microorganisms' activity of Najdi goats, so it may be used as an alternative for alfalfa (at 50% level) in susceptible areas.

Biochemical features and bioethanol production of microalgae from coastal waters of Pearl River Delta

This study describes identification, cultivation, monitoring of carbohydrate accumulation and bioethanol production from microalgal strains from the coastal waters of Pearl River Delta. Eighteen identified strains belong to the families Chlorellaceae, Scotiellocystoidaceae, Neochloridaceae, Selenastraceae and Scenedesmaceae. Of isolated strains Mychonastes afer PKUAC 9 and Scenedesmus abundans PKUAC 12 were selected for further biomass and ethanol production analysis. Comparison of three cultivation modes (stationary, shaken and aerated) resulted in the highest biomass productivity obtained for aerated cultures that yielded 0.09 g and 0.11 g dry weight per day per litre of medium for M. afer PKUAC 9 and S. abundans PKUAC 12, respectively. Carbohydrate accumulation monitored by FTIR showed that early stationary phase is optimal for biomass harvest. Microalgal biomass was successfully used as a carbohydrate feedstock for fermentative bioethanol production. S. abundans PKUAC 12 was superior feedstock for bioethanol production when pre-treated with the combination of dilute acid treatment and cellulase.

Development and use of quantitative competitive PCR assays for relative quantifying rumen anaerobic fungal populations in both in vitro and in vivo systems

This paper describes the use of a quantitative competitive polymerase chain reaction (QC-PCR) assay; using PCR primers to the rRNA locus of rumen fungi and a standard-control DNA including design and validation. In order to test the efficiency of this method for quantifying anaerobic rumen fungi, it has been attempted to evaluate this method in in vitro conditions by comparing with an assay based on measuring cell wall chitin. The changes in fungal growth have been studied when they are grown in in vitro on either untreated (US) or sodium hydroxide treated wheat straw (TS). Results showed that rumen fungi growth was significantly higher in treated samples compared with untreated during the 12d incubation (P<0.05) and plotting the chitin assay's results against the competitive PCR's showed high positive correlation (R(2)> or =0.87). The low mean values of the coefficients of variance in repeatability in the QC-PCR method against the chitin assay demonstrated more reliability of this new approach. And finally, the efficiency of this method was investigated in in vivo conditions. Samples of rumen fluid were collected from four fistulated Holstein steers which were fed four different diets (basal diet, high starch, high sucrose and starch plus sucrose) in rotation. The results of QC-PCR showed that addition of these non-structural carbohydrates to the basal diets caused a significant decrease in rumen anaerobic fungi biomass. The QC-PCR method appears to be a reliable and can be used for rumen samples.

Methods to study degradation of ruminant feeds

Ruman degradation is crucial in the supply of dietary nutrients to meet the nutrient demands of the anaerobic microbes and body tissues of ruminant animals. Therefore, it is essential to study the dynamics of rumen degradation of various feeds before their potential use to formulate nutritious diets for ruminant animals. Amongst many methods that have been used in the past, thein saccomethod has been the most effective method to study rumen degradation. However, this method is undesirable due to its implications for animal welfare and costs. While manyin vitromethods have been tested as possible alternatives to thein saccomethod to study rumen degradation of feeds, they were unable to remove the need to use fistulated animals to obtain rumen fluid. Although solubility, enzyme- and faeces-basedin vitromethods do not require rumen fluid, they still need data from either thein saccomethod or the rumen fluid-basedin vitromethods for comparison and validation. Therefore, there is a need to developin vitromethods that do not require the need to surgically modify ruminants to obtain rumen fluid to study rumen degradation. We review the potentials and problems associated with the existing methods to study rumen degradation and their implications for the animal industry in different situations.