Rumen Of Sheep Research Articles

Melatonin Sources in Sheep Rumen and Its Role in Reproductive Physiology

Melatonin Sources in Sheep Rumen and Its Role in Reproductive Physiology

Isolation and characterization of Methanosphaera sp. ISO3-F5, a member of a novel and widespread species of rumen methanogens growing with methanol plus hydrogen

Rumen methanogens predominantly fall into two physiological groups: hydrogenotrophs which use hydrogen (H2) to reduce carbon dioxide (CO2) to methane (CH4), and methylotrophs which use H2 to reduce methanol and methylamines as substrates for methanogenesis. We used a dilution to extinction approach to isolate two hydrogenotrophic Methanocatella spp. and four cultures of methylotrophic methanogens from sheep rumen contents. Three of the methylotrophs were stable mixed cultures containing methanogens belonging to different lineages of the order Methanomassiliicoccales and one was a pure Methanosphaera culture. Methanosphaera sp. ISO3-F5 has a comparatively large genome (2.68 Mb) comprised of two replicons, a chromosome and a megaplasmid. The genome has an average G + C content of 30.5 % and encodes 2360 putative protein-coding genes. Cells of ISO3-F5 have a spherical shape, 0.6–1.2 µm in diameter, usually occurring in pairs or loose clumps, and have no flagellum. Cells stain Gram positive, have a single thick cell wall and divide by the formation of a cross wall. The optimum temperature for growth was 39°C to 42°C and the optimum pH was 6.7–6.8. Acetate was required for growth, but CH4 was not produced from acetate, formate, ethanol, methylamine, or isopropanol with or without H2/CO2. Volatile fatty acids and rumen fluid were also found to enhance the growth of ISO3-F5, while coenzyme M did not. ISO3-F5 produced CH4 from methanol in the presence of H2 and the genes encoding the necessary methanogenesis pathway have been identified. Based on morphological, physiological, and genomic characteristics, ISO3-F5 is a new species of the genus Methanosphaera. Our study shows that simple isolation methods allowed us to culture diverse and significant members of the rumen methanogen community.

Effect of Dietary Concentrate-to-Forage Ratios During the Cold Season on Slaughter Performance, Meat Quality, Rumen Fermentation and Gut Microbiota of Tibetan Sheep.

This study aimed to investigate the effects of different dietary concentrate-to-forage ratios on slaughter performance, meat quality, rumen fermentation, rumen microbiota and fecal microbiota in Tibetan sheep. A total of sixty male Tibetan sheep were equally allocated into three dietary groups based on concentrate-to-forage ratios, i.e., 30:70 (C30), 50:50 (C50), and 70:30 (C70). Compared with the C30 group, sheep fed the C70 diet resulted in a higher (p < 0.05) slaughter live weight (SLW), hot carcass weight (HCW), dressing percentage (DP), eye muscle area, average daily gain (ADG), and ruminal total volatile fatty acids concentration and propionate molar proportion and lower (p < 0.05) shear force and cooking loss of meat, and ruminal acetate molar proportion and acetate:propionate ratio. Sheep in the C50 group exhibited a higher (p < 0.05) SLW, HCW, ADG, and ruminal propionate molar proportion and lower (p < 0.05) shear force and cooking loss of meat, and ruminal acetate molar proportion and acetate: propionate ratio compared with the C30 group. In rumen fluid, the relative abundance of Butyrivibrio was lower (p = 0.031) in the C30 group, and that of Ruminococcus was higher (p = 0.003) in the C70 group compared with the C50 group. In feces, genus Monoglobus and UCG_002 were the most abundant in the C30 group (p < 0.05), and the relative abundance of Prevotella was significantly higher in the C70 group than in other groups (p = 0.013). Correlation analysis revealed possible links between slaughter performance and meat quality and altered microbiota composition in the rumen and feces of Tibetan sheep. Overall, feeding a C70 diet resulted in superior carcass characteristics and meat quality in Tibetan sheep, thus laying a theoretical basis for the application of short-term remote feeding during the cold season.

The effects of compound probiotics on production performance, rumen fermentation and microbiota of Hu sheep.

Fungal probiotics have the potential as feed additives, but less has been explored in ruminant feed up to date. This study aimed to determine the effect of compound probiotics (CPs) with Aspergillus oryzae 1, Aspergillus oryzae 2 and Candida utilis on Hu sheep's growth performance, rumen fermentation and microbiota. A total of 120 male Hu sheep, aged 2 months and with the body weight of 16.95 ± 0.65 kg were divided into 4 groups. Each group consisted of 5 replicates, with 6 sheep per replicate. Group A was the control group fed with the basal diet. Group B, C and D was supplemented with the basal diet by adding 400, 800 and 1,200 grams per ton (g/t) CPs, respectively. The feeding trial lasted for 60 days after a 10-day adaptation period. The results showed that the average daily gain (ADG) of sheep in the CPs groups were significantly higher, the feed/gain were significantly lower than those in group A in the later stage and the overall period. The addition of CPs increased the economic benefit. The levels of CD4+ and the CD4+/CD8+ ratio in the CPs groups were higher than those in Group A. The levels of GSH, IgG, IL-2, IL-6, and IFN-γ in group C were significantly elevated compared with group A. Group B showed a significant increase in rumen NH3-N and cellulase activity. There was no difference in VFAs content between group A and group B, however, with the increasing addition of CPs, the butyric acid and isobutyric acid content tended to decrease. The rumen microbiota analysis indicated that the CPs addition increased the Firmicutes and Proteobacteria abundances, decreased the Bacteroidetes abundance. The correlation analysis showed that Prevotella was negatively correlated with ADG, and the addition of 400 CPs in group B reduced Prevotella's relative abundance, indicating CPs increased sheep growth by decreasing Prevotella abundance. The CPs addition reduced caspase-3, NF-κB and TNF-α expression in liver, jejunum and rumen tissues. In conclusion, the addition of CPs increased the sheep production performance, reduced inflammation, improved rumen and intestinal health. Considering the above points and economic benefits, the optimal addition of CPs as an additive for Hu sheep is 800 g/t.

Microbial-Metabolomic Exploration of Tea Polyphenols in the Regulation of Serum Indicators, Liver Metabolism, Rumen Microorganisms, and Metabolism in Hu Sheep.

This study investigated the impact of tea polyphenols on serum indices, rumen microorganisms, rumen metabolism, and liver metabolism in Hu sheep. Sixty healthy lambs, aged three months and with similar average weights, were chosen and randomly assigned to control (CON), TP400, TP800, and TP1200 groups, each consisting of fifteen lambs. The control group received a basal diet, while the experimental groups were provided with basal diet supplemented with 400 mg/kg, 800 mg/kg, and 1200 mg/kg of tea polyphenols, respectively. Compared with the CON group, the addition of tea polyphenols to the diet significantly increased serum IgA, GSH-Px, and TSOD. In addition, tea polyphenols were able to increase rumen pH but had no significant effect on the rumen NH3-N, VFA molar content, and the microbial top 10 phylum and genus levels. Moreover, Firmicutes predominated in the network map of the top 80 abundant microorganisms at the genus level, identifying 13 biomarkers at the genus level. In addition, strong correlations were observed between liver and rumen metabolites, particularly between rumen succinic acid and liver alanyl-serine and methylmalonic acid. Furthermore, tea polyphenol additions changed the enrichment of liver and rumen metabolites in the top five KEGG metabolic pathways, but 400-1200 mg/kg additions had no negative impact on the liver and rumen. In summary, TP significantly influences rumen and liver metabolites in Hu sheep, enhancing lamb immunity and antioxidant capacity, with 400 mg/kg being the most effective dosage.

Effects of Neem Tree Leaf Extract (Azadirachta I Ndica A. Juss) as Defaunating Agent of Sheep (Ovis Aries L.) Fed Napier Grass (Pennisetum Purpureum Schumach)

The effectiveness of neem tree leaf extract (NTLE) as defaunating agent was compared with sodium lauryl sulphate (SLS). Ten (10) sheep was used in the comparison of defaunating agents, the neem tree leaf extract was found to cause fluctuations in ruminal pH, similar to that of sodium lauryl sulphate, effectively reducing protozoal counts (from 296,000 cells/ml to 1,000 cells/ml) and increasing bacterial population (from 10,780 colony forming units/ml to 950,000 colony forming units /ml) in the rumen of sheep. It is therefore strongly advised to use neem tree extract as defaunating agents for sheep fed Napier grass to defaunated sheep in order to maximize food utilization and animal performance.

PERFORMANCE AND ECONOMICS OF PRODUCTION OF WEANER RABBITS FED WITH SUN-DRIED SHEEP RUMEN CONTENTS AS A REPLACEMENT FOR WHEAT OFFAL

The study was therefore, conducted to evaluate the performance and economics of production of weaner rabbits fed with varying levels of sun-dried sheep rumen contents (SDSRC) as replacement for wheat offal (WO). Fifty mongrel rabbits were allotted to five dietary treatments replicated five times in a completely randomized design with SDSRC replacing WO at 0, 25, 50, 75 and 100% designated as diet 1, 2, 3, 4 and 5, respectively. Growth performance, weight gain, feed intake and feed conversion ratio were not influenced (P&gt;0.05) by treatment. Feed cost (N/kg) and total feed cost (N) reduced as the percentage SDSRC increased. Lower4 values were recorded for diet 5(100% SDSRC) of N68.80 and N300.90 respectively. It is therefore, concluded that inclusion of SDSRC in the diet of weaner rabbits reduce cost of production without compromising their production attributes, it is therefore recommended for farmers to incorporate it, to reduce cost of production and environmental pollution in Nigeria.

Effects of Saccharomyces cerevisiae and Bacillus subtilis on in vitro fermentation in the rumen of Hu sheep.

The demand for animal products is increasing in developing countries due to population growth. However, livestock production contributes significantly to global warming, accounting for 25%. Probiotics can help improve livestock efficiency by enhancing gut microbes and fat metabolism. They can modify rumen populations, enhance fermentation, reduce methane emissions and improve feed digestion. In this study, the goal was to determine the most effective method of reducing methane emissions in the rumen of sheep in vitro by adding different concentrations of Saccharomyces cerevisiae and Bacillus subtilis. Adding 8 × 106 CFU g-1 S. cerevisiae during fermentation reduced pH levels after 48 h. This also increased the concentrations of NH3-N, microbial protein and total gas production. At the same time, it decreased methane emissions. Furthermore, adding 20 × 106 CFU g-1 B. subtilis to the mixture increased total gas production (TGP) and methane production, with the highest production observed after 48 h. However, it did not affect pH levels after 48 h. It can be concluded that S. cerevisiae had significantly increased microbial protein and NH3-N concentrations after fermentation without altering pH. Additionally, the addition of S. cerevisiae enhanced TGP and reduced methane emissions. It is worth noting that TGP increased because B. subtilis was added at a concentration of 20 × 106 CFU g-1, with no significant differences between concentrations. Therefore, we recommend adding S. cerevisiae and B. subtilis to the diet at doses of 8 and 20 × 106 CFU g-1, as it resulted in higher TGP and reduced methane emissions. © 2024 Society of Chemical Industry.

Analysis of the microbiota between the rumen and duodenum in sheep with hay-concentrate feeding

Analysis of the microbiota between the rumen and duodenum in sheep with hay-concentrate feeding

Impact of wheat processing on growth, serum biochemistry, and ruminal microbiota in sheep (Ovis aries)

This study investigated the impact of wheat processing methods (wheat flour vs wheat pellets) on the growth performance, serum biochemical parameters, and rumen microbiome composition in sheep. Results indicated that feeding of wheat flour resulted in significantly higher terminal weight and average daily gain (P < 0.05) and lower cholesterol and ALP04 levels (P < 0.05) in sheep compared to those fed wheat pellets. Analysis of 16s rDNA high-throughput sequencing data revealed significantly higher microbial richness (Chao1 index) in the rumen of sheep fed wheat flour (P < 0.05), even though the phylum-level composition dominated by Firmicutes, Bacteroidetes, and Proteobacteria was similar in both groups of sheep. Notably, sheep fed wheat flour were found to have a significantly higher relative abundance of Bacteroidetes (P < 0.05). At the genus level, Succinivibrionaceae_UCG-001 and Prevotella_1 were significantly more abundant in the rumen of sheep fed wheat flour (P < 0.05). Correlation analysis identified that both terminal weight and average daily gain were positively correlated with ruminal abundance of Bacteroidetes and Prevotella_1, while ALP04 was negatively correlated with the abundance of these taxa. Functional prediction using PICRUSt2 indicated enrichment of pathways related to the ABC-type glycerol-3-phosphate transport system, and periplasmic components in both wheat flour and pellet fed sheep. Overall, these findings suggest that dietary wheat flour modulates rumen microbiota composition, and improves growth performance in sheep.

Microbiological indicators in the rumen of sheep when fed different levels of concentrates

Microbiological indicators in the rumen of sheep when fed different levels of concentrates

Evaluating the Safety of Bacillus cereus GW-01 Obtained from Sheep Rumen Chyme.

Bacillus cereus is responsible for 1.4-12% food poisoning outbreaks worldwide. The safety concerns associated with the applications of B. cereus in health and medicine have been controversial due to its dual role as a pathogen for foodborne diseases and a probiotic in humans and animals. In this study, the pathogenicity of B. cereus GW-01 was assessed by comparative genomic, and transcriptome analysis. Phylogenetic analysis based on a single-copy gene showed clustering of the strain GW-01, and 54 B. cereus strains from the NCBI were classified into six major groups (I-VI), which were then associated with the source region and sequence types (STs). Transcriptome results indicated that the expression of most genes related with toxins secretion in GW-01 was downregulated compared to that in the lag phase. Overall, these findings suggest that GW-01 is not directly associated with pathogenic Bacillus cereus and highlight an insightful strategy for assessing the safety of novel B. cereus strains.

Characterization of the ruminal microbiota in sheep and goats fed different levels of tannin-rich Sericea lespedeza hay.

Understanding ruminal microbiota and diet-host breed interactions under forage feeding conditions is essential for optimizing rumen fermentation and improving feed efficiency in small ruminants. This study aimed to investigate the effects of different ratios of condensed tannin-rich Sericea lespedeza (SL; Lespedeza cuneata) in the diets on changes and interactions of ruminal microbiota and host species (i.e., sheep and goats). Katahdin sheep (n = 12) and Alpine goats (n = 12) at approximately 10 to 12 mo of age were blocked by body weight (BW = 30.3 and 25.5kg, respectively) and randomly assigned to one of the 3 treatments. Diets contained 75% coarsely ground forage and 25% concentrate. The forages were 1) 100% alfalfa hay (AL), 2) 100% SL, and 3) 50% AL + 50% SL (ASL). In the present study, the diversity and composition of ruminal microbiota differed between sheep and goats fed similar diets. Based on the taxonomic analysis, there was a distinct clustering pattern (P < 0.05) for sheep by diets, but such a pattern was not observed for goats (P > 0.1). The most predominant phyla were Firmicutes, Bacteroidetes, Ascomycota, and methanogen species of Methanobrevibactor sp. in the rumen of sheep and goats, regardless of diets. The Bacteroidetes and Ascomycota were enriched in sheep fed AL and ASL. In contrast, these microbial phyla were enhanced in goats fed tannin-rich SL diets, with the diet-by-host species interaction (P < 0.02) for the Bacteroidetes phylum. Sheep rumen fluid samples showed a higher degree of variability in microbial community composition compared to goat rumen fluid samples. The relative proportion of the Aspergillus fungi population was reduced to 90.7% in the SL group compared with the AL group, regardless of host species. The antimicrobial activity of tannins and greater sensitivities of selected microbiota species to these tannin compounds during SL feeding in sheep and goats perhaps caused this difference. The results from this study suggest that differences in the microbiota were associated with differences in diets and host species. Therefore, this study provides a better understanding of ruminal microbiota and diet-host species interactions under various tannin-rich diets, which could advance consolidative information on rumen microbiome community diversity changes and may improve sheep and goat production.

Expression and characterization of a novel microbial GH9 glucanase, IDSGLUC9-4, isolated from sheep rumen.

This study aimed to identify and characterize a novel endo-β-glucanase, IDSGLUC9-4, from the rumen metatranscriptome of Hu sheep. A novel endo-β-glucanase, IDSGLUC9-4, was heterologously expressed in Escherichia coli and biochemically characterized. The optimal temperature and pH of recombinant IDSGLUC9-4 were determined. Subsequently, substrate specificity of the enzyme was assessed using mixed-linked glucans including barley β-glucan and Icelandic moss lichenan. Thin-layer chromatography (TLC), high-performance liquid chromatography (HPLC), matrix assisted laser desorption ionization time of flight mass spectrometry analyses were conducted to determine the products released from polysaccharides and cello-oligosaccharides substrates. The recombinant IDSGLUC9-4 exhibited temperature and pH optima of 40°C and pH 6.0, respectively. It exclusively hydrolyzed mixed-linked glucans, with significant activity observed for barley β-glucan (109.59±3.61 μmol/mg min) and Icelandic moss lichenan (35.35±1.55 μmol/mg min). TLC and HPLC analyses revealed that IDSGLUC9-4 primarily released cellobiose, cellotriose, and cellotetraose from polysaccharide substrates. Furthermore, after 48 h of reaction, IDSGLUC9-4 removed most of the glucose, indicating transglycosylation activity alongside its endo-glucanase activity. The recombinant IDSGLUC9-4 was a relatively acid-resistant, mesophilic endo-glucanase (EC 3.2.1.4) that hydrolyzed glucan-like substrates, generating predominantly G3 and G4 oligosaccharides, and which appeared to have glycosylation activity. These findings provided insights into the substrate specificity and product profiles of rumen-derived GH9 glucanases and contributed to the expanding knowledge of cellulolytic enzymes and novel herbivore rumen enzymes in general.

Prickly ash seeds can promote healthy production of sheep by regulating the rumen microbial community.

This study aimed to investigate the effect of prickly ash seeds (PAS) on the microbial community found in rumen microbes of Hu sheep by adding different percentages of prickly ash seeds and to carry out research on the relation between rumen flora and production performance. Twenty-seven male lambs of Hu sheep were classified into three groups based on the content of prickly ash seeds (PAS) fed for 90 days, i.e., 0%, 3%, and 6%. At the end of the feeding trial, rumen fluid samples were collected from six sheep in each group for 16S amplicon sequencing. The results showed that the addition of prickly ash seeds significantly increased both Chao1 and ACE indices (P < 0.05), and the differences between groups were greater than those within groups. The relative content of Bacteriodota decreased, and the relative content of Fusobacteriota, Proteobacteria, Acidobacteriota, and Euryarchaeota increased. The relative content of Papillibacter and Saccharofermentans was increased at the genus level, and the relative content of Bacteroides and Ruminococcus was decreased. The test group given 3% of prickly ash seeds was superior to the test group given 6% of prickly ash seeds. In addition, the addition of 3% of prickly ash seeds improved the metabolism or immunity of sheep. Fusobacteriota and Acidobacteriota were positively correlated with total weight, dressing percentage, and average daily gain (ADG) and negatively correlated with average daily feed intake (ADFI), feed-to-gain ratio (F/G), and lightness (L*). Methanobrevibacter and Saccharofermentans were positively correlated with ADG and negatively correlated with ADFI and L*. In conclusion, under the present experimental conditions, the addition of prickly ash seeds increased the abundance and diversity of rumen microorganisms in Hu sheep and changed the relative abundance of some genera. However, the addition of 6% prickly ash seeds may negatively affect the digestive and immune functions in sheep rumen.

Study of Fauna and Ecology of Species Belonging to Entodynimorpha in the Regions of Nakhchivan Autonomous Republic

Rumen Protozoa are strictly anaerobic and highly specialized ciliates and can live only in the rumen and similar habitats. These Ciliata play an important role in feed utilization and indicate the environmental impact (methane emissions and nitrogen excretion) of ruminant production. Digestion of feed in ruminants depends on the life activity of microorganisms. Without their help, ruminants could not assimilate cellulose with simple non-protein compounds. These microorganisms located in rumen decompose the organic substances in the feed and form volatile fatty acids, ammonia, amino acids, which animals use for their development and reproduction. In the rumen of domesticated cattle and sheep, rumen cilia constitute 20-50% of the total microbial biomass. Rumen Ciliata develop symbiotic relationships with their animal hosts and both symbiotic and predator-prey relationships with other members of the rumen microbiota. The lack of axenic cultures of rumen Ciliata has forced researchers to use other methods to determine the metabolism and functions of rumen Protozoa, such as comparing rumen fermentation and microbial profiles of faunal and non-ciliated cattle or sheep or using in vitro cultures.

Isolation and characterization of tanninolytic bacteria from sheep rumen contents: Assessment of tannin degrading, fibrolytic and feed digestibility potential

To counteract the negative effects of phytotannins, ruminants host a diverse community of bacteria that break down tannins. These bacteria not only possess tanninolytic activity but also have other functional relevance which has not been properly examined. Therefore, the present study was conducted to isolate and characterize tannin degrading bacteria (TDB) with possible fibrolytic activity from rumen of sheep fed tannin-rich diet. Based on the development of a clear zone on tannin-enriched agar plates, a total of 24 isolates were screened as tannin hydrolyzing bacteria. Majority of the isolates were gram positive cocci. The isolates could tolerate phenolic monomers such as ferulic acid, gallic acid, vanillic acid up to 30 mM and pyrogallol up to 10 mM however, the isolates failed to grow in presence of syringic acid, p-coumaric acid and p-hydroxybenzoic acid. Highest tannase activity was observed in isolate TDB23 while, lowest in isolates TDB2 and TDB5. In terms of fibrolytic activity, maximum endoglucanase, exoglucanase, and FPase activity was observed in isolate TDB9. In vitro digestibility of Prosopis cineraria leaves was considerably enhanced by inoculation of isolate TDB23 followed by TDB9. Therefore, the screened isolates demonstrated promising tannin and fibre degrading potential which can be further explored as direct-fed microbial in ruminants for effective utilization of tannin-rich fibrous feeds.

Effects of Garlic Oil and Cinnamaldehyde on Sheep Rumen Fermentation and Microbial Populations in Rusitec Fermenters in Two Different Sampling Periods.

Garlic oil (GO) and cinnamaldehyde (CIN) have shown potential to modify rumen fermentation. The aim of this study was to assess the effects of GO and CIN on rumen fermentation, microbial protein synthesis (MPS), and microbial populations in Rusitec fermenters fed a mixed diet (50:50 forage/concentrate), as well as whether these effects were maintained over time. Six fermenters were used in two 15-day incubation runs. Within each run, two fermenters received no additive, 180 mg/L of GO, or 180 mg/L of CIN. Rumen fermentation parameters were assessed in two periods (P1 and P2), and microbial populations were studied after each of these periods. Garlic oil reduced the acetate/propionate ratio and methane production (p < 0.001) in P1 and P2 and decreased protozoal DNA concentration and the relative abundance of fungi and archaea after P1 (p < 0.05). Cinnamaldehyde increased bacterial diversity (p < 0.01) and modified the structure of bacterial communities after P1, decreased bacterial DNA concentration after P2 (p < 0.05), and increased MPS (p < 0.001). The results of this study indicate that 180 mg/L of GO and CIN promoted a more efficient rumen fermentation and increased the protein supply to the animal, respectively, although an apparent adaptive response of microbial populations to GO was observed.

Impact of feeding native Caatinga pasture on the rumen histomorphometry of sheep raised in semi-extensive management.

In the northeastern region of Brazil, sheep and goat farming, encompassing around 20 million animals, is predominantly a subsistence activity. Forage quality plays a crucial role in animal productivity, posing a complex interplay between plant and animal aspects. The Caatinga biome, vital for livestock in the region, serves as a significant source for animal diet through pastures. This study aimed to conduct a histomorphometric evaluation of sheep rumens in a semi-extensive system, comparing those feeding on native Caatinga pastures to those on cultivated pastures. Histological processing followed standard protocols, with morphometry focusing on six viable rumen papillae and the submucosa and muscular layer thickness. Statistical correlation analysis revealed morphological differences in papillae across various rumen regions. Morphometric data indicated no significant difference in papillae area between the groups, with average values in Group A surpassing those in Group B, except for width. This study establishes a morphological and morphometric pattern for rumen regions linked to diet types-native or cultivated. The findings not only enhance understanding of the dietary foundation in the Caatinga's extensive system, but also contribute valuable insights for formulating nutritional strategies to enhance sheep production in the region. This research sheds light on the intricacies of forage-based animal nutrition, particularly in semi-extensive systems, offering a foundation for future studies and practices to optimise livestock management in the northeastern Brazilian context.

Complete genome sequence of Methanosphaera sp. ISO3-F5, a rumen methylotrophic methanogen.

Methanosphaera spp. are methylotrophic methanogenic archaea and members of the order Methanobacteriales with few cultured representatives. Methanosphaera sp. ISO3-F5 was isolated from sheep rumen contents in New Zealand. Here, we report its complete genome, consisting of a large chromosome and a megaplasmid (GenBank accession numbers CP118753 and CP118754, respectively).