In this study, 207 strains of aerobic and facultatively anaerobic cellulolytic bacteria were isolated from the gut of Holotrichia parallela larvae. These bacterial isolates were assigned to 21 genotypes by amplified ribosomal DNA restriction analysis (ARDRA). A partial 16S rDNA sequence analysis and standard biochemical and physiological tests were used for the assignment of the 21 representative isolates. Our results show that the cellulolytic bacterial community is dominated by the Proteobacteria (70.05%), followed by the Actinobacteria (24.15%), the Firmicutes (4.35%), and the Bacteroidetes (1.45%). At the genus level, Gram-negative bacteria including Pseudomonas, Ochrobactrum, Rhizobium, Cellulosimicrobium, and Microbacterium were the predominant groups, but members of Bacillus, Dyadobacter, Siphonobacter, Paracoccus, Kaistia, Devosia, Labrys, Ensifer, Variovorax, Shinella, Citrobacter, and Stenotrophomonas were also found. Furthermore, our results suggest that a significant amount of bacterial diversity exists among the cellulolytic bacteria, and that Siphonobacter aquaeclarae, Cellulosimicrobium funkei, Paracoccus sulfuroxidans, Ochrobactrum cytisi, Ochrobactrum haematophilum, Kaistia adipata, Devosia riboflavina, Labrys neptuniae, Ensifer adhaerens, Shinella zoogloeoides, Citrobacter freundii, and Pseudomonas nitroreducens are reported to be cellulolytic for the first time in this study. Our results indicate that the scarab gut is an attractive source for the study of novel cellulolytic microorganisms and enzymes useful for cellulose degradation.

Degradation of rice straw by cooperative microbial activities is at present the most attractive alternative to fuels and provides a basis for biomass conversion. The use of microbial consortia in the biodegradation of lignocelluloses could reduce problems such as incomplete synergistic enzymes, end-product inhibition, and so on. In this study, a cellulolytic microbial consortium was enriched from the hindgut of Holotrichia parallela larvae via continuous subcultivation (20 subcultures in total) under static conditions. The degradation ratio for rice straw was about 83.1% after three days of cultivation, indicating its strong cellulolytic activity. The diversity analysis results showed that the bacterial diversity and richness decreased during the consortium enrichment process, and the consortium enrichment process could lead to a significant enrichment of phyla Proteobacteria and Spirochaetes, classes Clostridia, Epsilonproteobacteria, and Betaproteobacteria, and genera Arcobacter, Treponema, Comamonas, and Clostridium. Some of these are well known as typical cellulolytic and hemicellulolytic microorganisms. Our results revealed that the microbial consortium identified herein is a potential candidate for use in the degradation of waste lignocellulosic biomass and further highlights the hindgut of the larvae as a reservoir of extensive and specific cellulolytic and hemicellulolytic microbes.

In this study, we used a culture-independent method based on library construction and sequencing to analyze the genetic diversity of the cellulase and hemicellulase genes of the bacterial community resident in the hindgut of Holotrichia parallela larvae. The results indicate that there is a large, diverse set of bacterial genes encoding lignocellulose hydrolysis enzymes in the hindgut of H. parallela. The total of 101 distinct gene fragments (similarity <95%) of glycosyl hydrolase families including GH2 (24 genes), GH8 (27 genes), GH10 (19 genes), GH11 (14 genes) and GH36 (17 genes) families was retrieved, and certain sequences of GH2 (10.61%), GH8 (3.33%), and GH11 (18.42%) families had <60% identities with known sequences in GenBank, indicating their novelty. Based on phylogenetic analysis, sequences from hemicellulase families were related to enzymes from Bacteroidetes and Firmicutes. Fragments from cellulase family were most associated with the phylum of Proteobacteria. Furthermore, a full-length endo-xylanase gene was obtained, and the enzyme exhibited activity over a broad range of pH levels. Our results indicate that there are large number of cellulolytic and xylanolytic bacteria in the hindgut of H. parallela larvae, and these symbiotic bacteria play an important role in the degradation of roots and other organic matter for the host insect.

This study was carried out in an attempt to evaluate the impact of Broussonetia papyrifera as a roughage substitute at different levels on carcase traits, growth performance, meat quality and immune performance in Hu ram lambs. Sixty Hu rams (5 months of age, 26.70 ± 2.14 kg body weight) were randomly divided into four groups. The treatments comprised B. papyrifera supplementation at levels of 0% (G0), 30% (G30), 60% (G60) and 100% (G100) of roughage feed. The results suggested that diet supplemented with B. papyrifera (G100 group) caused a higher average weight gain (AWG) and average daily gain (ADG) than those of G0 group. The highest carcase weight was observed in the G60 group. The chemical and physical properties of the longissimus dorsi muscle of Hu rams showed no significant differences (p>.05). For fatty acid, the G60 group had significantly lower content of saturated fatty acids (SFAs), higher contents of monounsaturated fatty acids (MUFAs) and polyunsaturated fatty acids (PUFAs) and higher PUFA/SFA ratio than other groups (p<.05). In terms of the immune response, G60 and G100 groups significantly showed a significant rise in the immunoglobulins (IgG, IgA and IgM) (p<.05). This study indicated multiple beneficial effects of the inclusion of B. papyrifera (60% of the roughage feed) on the growth performance, carcase traits, meat quality and immune response in Hu rams. It could be used as a high-quality unconventional feedstuff for rams.

Methane production is the main gas energy loss in ruminants and generates a powerful greenhouse gas that contributes to climate changes. Macleaya cordata is a plant commonly utilized additive in livestock diet as it contains various chemical compounds with beneficial health effects. This study aimed to explore the influence of M. cordata extract on in vitro methanogenesis and rumen fermentation. Three cannulated Jingjiang cattle were used as rumen fluid donors. The mixture of rumen fluid and a buffer (60 ml, 1:2 volume ratio) was treated with 6 different concentrations of M. cordata extract (0.01%, 0.11%, 0.21%, 0.31%, 0.41%, and 0.51%) and incubated for 12 and 24 hr. The control sample, with no addition of plant extract, was also analyzed. At each time point, pH, total gas, methane, dry matter (DM) digestibility, neutral detergent fiber (NDF), acid detergent fiber (ADF), ammonia nitrogen (NH₃-N), microbial protein (MCP), and volatile fatty acids (VFA) concentrations were determined. Total gas production decreased with increasing the amount of M. cordata extract at all time points. Methane production also decreased dose-dependently with M. cordata extract after 3, 6, 9, and 12 hr of incubation, but increased after 24 hr. M. cordata extract decreased the concentration of NH₃-N and VFA, and the amount of acetic, propionic, and butyric acid. M. cordata extract decreased the MCP concentration after 12 hr, but its level returned to the initial value after 24 hr. Supplementation with 0.01, 0.11, and 0.21% of M. cordata extract did not affect the DM digestibility. However, supplementation with 0.31, 0.41, and 0.51% of M. cordata extract significantly decreased the DM digestibility. Supplementation with 0.11% of M. cordata extract effectively reduced methane production without affecting the DM digestion in vitro. However, its effect on in vivo methane production, rumen fermentation, and ruminant production requires further investigation.