Characterization of Streptococcus bovis from the rumen of the dromedary camel and Rusa deer

Biodegradability of PBAT/PLA coated paper and bioplastic bags under anaerobic digestion

Poly (lactic acid) (PLA) and Poly(butylene adipate-co-terephthalate) (PBAT) are two of biodegradable plastics with the highest production capacities in 2021. Bioplastic waste management can be easily integrated with organic waste management, especially when bioplastics are used as food packaging material, since they are potentially biodegradable. The aim of this study was to assess the biodegradability of biodegradable polymer-coated paper (BPCP) and bioplastic bags made from PBAT/PLA blend during mesophilic and thermophilic anaerobic digestion (AD) and to reveal the changes in the physicochemical properties of the bioplastics. BPCP obtained 155 NmL-CH4/g VS and 307.3 NmL-CH4/g VS under mesophilic and thermophilic conditions, respectively, but left bioplastic film residues. The bioplastic bags did not exhibit significant biodegradation during the AD processes. 1H NMR results indicated that the ratio of PLA to PBAT decreased significantly after AD of the BPCP film and that PLA monomers were formed from the bioplastic bags, leading to a decrease in the hydrophobicity on the surfaces of the materials. Methanoculleus was found to be enriched on the bioplastic surface after mesophilic AD. From the perspective of coupling bioplastic waste management with the food waste management, the incorporation of BPCP into the AD reactor not only enhances system stability and methane production to a greater extent than biodegradable plastic bags but also raises concerns regarding the residual biofilm when utilizing the digestate for direct land applications.

Isolation and characterization of tannin-degrading bacteria from the rumen of wild Hokkaido sika deer (Cervus nippon yezoensis)

We isolated tannin-degrading bacteria from the rumen of wild Hokkaido sika deer and characterized their phylogeny and tannase activity in relation to sample sources. The condensed tannin level was higher in all deer rumen samples (n = 20) than in forage-fed cattle rumen samples (n = 6), whereas no hydrolyzable tannins were detected in any of the rumen samples. Rumen bacteria were enumerated on nonselective brain heart infusion (BHI) agar medium and then transferred onto tannic acid-containing BHI agar plates to screen for bacteria only showing growth (tannin-resistant bacteria) and those showing both growth and a clear zone (tannin-degrading bacteria). Summer samples provided only tannin-resistant bacteria, none of which showed tannin-degrading activity. Although winter samples also provided tannin-resistant bacteria, most isolates exhibited tannin-degrading activity. A total of 70 isolates exhibiting tannin-degrading activity were classified as Streptococcus bovis group based on 16S rRNA gene sequencing and further classified into two groups, either group A or group B. Group A consisted of isolates showing weak tannase activity, whereas group B included a majority of the isolates exhibiting high tannase activity. These results suggest that wild Hokkaido sika deer develop tannin-degrading Streptococcus in the rumen during winter, which allows access to woody food materials rich in tannins.

Population shifts in some faeces and rumen bacteria profiles and subsequent blood LPS and lactate concentrations in lambs in the early period of subacute ruminal acidosis

BACKGROUND

It is known that ruminal acidosis can induce harmal population shifts in some ruminal bacteria profiles. However, there is little information related to alterations in faecal and ruminal bacterial communities and relevant serum lipopolysaccharide (LPS) in sheep with subacute ruminal acidosis (SARA).

OBJECTIVES

This study aimed to investigate alterations in the defined faecal and ruminal bacteria profiles and serum LPS and blood lactate concentrations in lambs with empirically induced SARA.

METHODS

Fifteen lambs were served and undergone to induce SARA during a 7-day period. Faecal and ruminal samples were taken to measure the pH and to perform the bacteriological works at 0 (just before induction), 8, 9, and 10 days of the challenge. Blood samples were collected to determine the serum LPS and lactate levels. The rumen and faecal samples were cultured to specify colony-forming units (CFU) for Escherichia coli, Streptococcus Group D (SGD), and lactic acid bacteria (LAB).

RESULTS

Serum LPS value had no significant increase in the affected lambs with SARA. Significant increasing trends were observed in faecal E. coli and LAB populations (p < 0.01). Rumen bacteriology revealed a rising trend for LAB and a falling trend for SGD populations (p < 0.01).

CONCLUSION

Unlike cattle, LPS appears to be of minor importance in the pathogenesis of SARA in sheep. The increased ruminal and faecal LAB (4.00 × 10⁷ CFU/ml or g) are proposed as valuable biomarkers for improving nutritional strategy and screening SARA in lambs.

The Influence of Essential Oils on Gut Microbial Profiles in Pigs

Simple Summary

In recent years, the intake of ultra-processed foods has increased dramatically worldwide. Missing natural foods in the diet raise the need of biologically active food components that could compensate for this deficiency and help maintain proper immune status. In this study, the microbial changes in pigs as experimental animals were assessed as influenced by consumption of oregano extract combination with peppermint and thyme essential oils. The results demonstrated that the combination of plant extracts had a positive effect on the gastrointestinal tract of animals by increasing the number of probiotic bacteria. Based on the results obtained it may be outlined that the combination of oregano extract and peppermint and thyme essential oils can be promising ingredient as a functional component for the development of the new nutraceutical preparation.

Abstract

In recent years, the intake of ultra-processed foods has increased dramatically worldwide. Missing natural foods in the diet raise the need of biologically active food components that could compensate for this deficiency and help maintain proper immune status. This study used pigs as an animal model for the assessment of the impact of consumption of Origanum vulgare plant extract combined with Mentha piperita and Thymus vulgaris essential oils on microbial profile in intestines. A single group of weaned pigs received basal diet, while the other group basal diet supplemented with plant extract and two essential oils in the form of bilayer tablets prepared using “liquid/solid” phase technology. Metagenomic sequencing was performed with the aim to investigate changes of microbial communities in ileum, caecum, and colon. The results demonstrated that the combination of essential oils was non cytotoxic, and had a positive effect on the microbial composition in the large intestine of pigs due to significant increase in the number of probiotic bacteria. The amount of Lactobacillus was 2.5 times and Bifidobacterium 1.9 times higher in the animal group fed with supplement. The combination, however, had some negative impact on the variety of minor species in the distal part of the ileum. Additional studies need to be performed to obtain knowledge on how combinations of essential oils can change bacterial variety in the proximal part of the gastrointestinal tract.

Comparative analysis of fecal microbial communities in cattle and Bactrian camels

Bactrian camels may have a unique gastrointestinal (GI) microbiome because of their distinctive digestive systems, unique eating habits and extreme living conditions. However, understanding of the microbial communities in the Bactrian camel GI tract is still limited. In this study, microbial communities were investigated by comparative analyses of 16S rRNA hypervariable region V4 sequences of fecal bacteria sampled from 94 animals in four population groups: Inner Mongolian cattle (IMG-Cattle), Inner Mongolian domestic Bactrian camels (IMG-DBC), Mongolian domestic Bactrian camels (MG-DBC), and Mongolian wild Bactrian camels (MG-WBC). A total of 2,097,985 high-quality reads were obtained and yielded 471,767,607 bases of sequence. Firmicutes was the predominant phylum in the population groups IMG-Cattle, IMG-DBC and MG-WBC, followed (except in the Inner Mongolian cattle) by Verrucomicrobia. Bacteroidetes were abundant in the IMG-DBC and MG-WBC populations. Hierarchical clustered heatmap analysis revealed that the microbial community composition within the three Bactrian camel groups was relatively similar, and somewhat distinct from that in the cattle. A similar result was determined by principal component analysis, in which the camels grouped together. We also found several species-specific differences in microbial communities at the genus level: for example, Desulfovibrio was abundant in the IMG-DBC and MG-WBC groups; Pseudomonas was abundant in the IMG-Cattle group; and Fibrobacter, Coprobacillus, and Paludibacter were scarce in the MG-WBC group. Such differences may be related to different eating habits and living conditions of the cattle and the various camel populations.

Streptococcus bovis/S. equinus complex septicemia in a group of calves following intramuscular vaccination

Organisms previously classified as Streptococcus bovis (i.e., the S. bovis/S. equinus complex) are common in cattle feces, but may also act as opportunistic pathogens. In the current work, Streptococcus infantarius subsp. coli, a member of this complex, was associated of a cluster of calves that died within hours of injection with a modified live viral vaccine. Within 12 h of vaccination of 46 calves at a cow/calf operation, 4 calves had died, 3 calves were ill, and 1 unvaccinated cow was dead. Autopsies were performed on the cow, 2 dead calves, and 1 affected surviving calf, which was euthanized ~24 h after vaccine administration. The animals had similar gross anatomic and microscopic lesions, including subcutaneous and intramuscular dark hemorrhage on the caudal neck, multiorgan ecchymosis and petechiation, and alveolitis to interstitial pneumonia. Gram-positive cocci were in the vasculature of the lung and skeletal muscle, and S. infantarius subsp. coli was cultured from tissues and from the vaccines used on affected animals, but not in vials used on unaffected animals. Together, these findings suggest death caused by streptococcal septicemia and toxemia as a result of contamination.

Genomics, evolution, and molecular epidemiology of the Streptococcus bovis/Streptococcus equinus complex (SBSEC)

The Streptococcus bovis/Streptococcus equinus complex (SBSEC) is a group of human and animal derived streptococci that are commensals (rumen and gastrointestinal tract), opportunistic pathogens or food fermentation associates. The classification of SBSEC has undergone massive changes and currently comprises 7 (sub)species grouped into four branches based on sequences identities: the Streptococcus gallolyticus, the Streptococcus equinus, the Streptococcus infantarius and the Streptococcus alactolyticus branch. In animals, SBSEC are causative agents for ruminal acidosis, potentially laminitis and infective endocarditis (IE). In humans, a strong association was established between bacteraemia, IE and colorectal cancer. Especially the SBSEC-species S. gallolyticus subsp. gallolyticus is an emerging pathogen for IE and prosthetic joint infections. S. gallolyticus subsp. pasteurianus and the S. infantarius branch are further associated with biliary and urinary tract infections. Knowledge on pathogenic mechanisms is so far limited to colonization factors such as pili and biofilm formation. Certain strain variants of S. gallolyticus subsp. macedonicus and S. infantarius subsp. infantarius are associated with traditional dairy and plant-based food fermentations and display traits suggesting safety. However, due to their close relationship to virulent strains, their use in food fermentation has to be critically assessed. Additionally, implementing accurate and up-to-date taxonomy is critical to enable appropriate treatment of patients and risk assessment of species and strains via recently developed multilocus sequence typing schemes to enable comparative global epidemiology. Comparative genomics revealed that SBSEC strains harbour genomics islands (GI) that seem acquired from other streptococci by horizontal gene transfer. In case of virulent strains these GI frequently encode putative virulence factors, in strains from food fermentation the GI encode functions that are pivotal for strain performance during fermentation. Comparative genomics is a powerful tool to identify acquired pathogenic functions, but there is still an urgent need for more physiological and epidemiological data to understand SBSEC-specific traits.

Acute septicemia caused by Streptococcus gallolyticus subsp. pasteurianus in turkey poults

Streptococcus gallolyticus, previously known as Streptococcus bovis biotypes I and II/2, is a well-known cause of sepsis and meningitis in humans and birds. The present case report describes an outbreak of fatal septicemia associated with S. gallolyticus subsp. pasteurianus (S. bovis biotype II/2) in 11 turkey flocks in Pennsylvania between 2010 and 2013. Affected poults were 2-3 wk of age. Major clinical observation was sudden increase in mortality among turkey poults without any premonitory clinical signs. Postmortem examination findings revealed acute septicemia with lesions such as fibrinous pericarditis, meningitis, splenic multifocal fibrinoid necrosis, hepatitis, osteochondritis, myositis, and airsacculitis. Gram-positive cocci were isolated from several organs by routine bacterial culture. Biotyping identified bacteria as streptococci, whereas 16S ribosomal RNA gene sequencing identified them as S. gallolyticus subsp. pasteurianus. Antibiotic susceptibility profiles revealed that all the strains isolated were sensitive to penicillin and erythromycin with different sensitivity profiles for other antibacterial agents tested. The present study reports the first confirmed case of acute septicemia in turkey poults caused by S. gallolyticus subsp. pasteurianus.

The effect of fibre source on the numbers of some fibre-degrading bacteria of Arabian camel's (Camelus dromedarius) foregut origin

The total bacterial community of Fibrobacter succinogenes and Ruminococcus flavefaciens in fibre-enriched culture of the foregut contents of 12 adult feral camels (Camelus dromedaries) fed on native vegetation in Australia was investigated using quantitative PCR. Foregut contents were collected postmortem, pooled and filtered before divided into two fractions. One fraction was used for extraction of DNA, while the other fraction was inoculated straight away into BM 10 contained filter paper (FP), cotton thread (CT) or neutral detergent fibre (NDF) as the sole carbohydrate sources in Hungate tubes. The tubes were incubated anaerobically at 39 °C for 1 week. After a near complete degradation of the FP and CT and extensive turbidity in the NDF, media subculturing was carried out into fresh media tubes. This was repeated twice before genomic DNA was extracted and used for quantification of bacteria. Using an absolute quantification method, the numbers of cells in 1 ml of each sample ranged from 4.07 × 10(6) to 2.73 × 10(9) for total bacteria, 1.34 × 10(3) to 2.17 × 10(5) for F. succinogenes and 5.78 × 10(1) to 3.53 × 10(4) for R. flavefaciens. The mean cell number of F. succinogenes was highest in the FP enrichment medium at approximately 107-fold, whereas for the R. flavefaciens targeted primer, the NDF enrichment media had the highest mean cell number at approximately 4-fold when compared to the rumen content. The data presented here provide evidence of fibre type preference by the two main fibre-degrading bacteria and would help us understand the interaction between fibre type and fibre-degrading microorganisms, which has ramification on camel nutrition at different seasons and environments.

Methane emission by camelids

Methane emissions from ruminant livestock have been intensively studied in order to reduce contribution to the greenhouse effect. Ruminants were found to produce more enteric methane than other mammalian herbivores. As camelids share some features of their digestive anatomy and physiology with ruminants, it has been proposed that they produce similar amounts of methane per unit of body mass. This is of special relevance for countrywide greenhouse gas budgets of countries that harbor large populations of camelids like Australia. However, hardly any quantitative methane emission measurements have been performed in camelids. In order to fill this gap, we carried out respiration chamber measurements with three camelid species (Vicugna pacos, Lama glama, Camelus bactrianus; n = 16 in total), all kept on a diet consisting of food produced from alfalfa only. The camelids produced less methane expressed on the basis of body mass (0.32±0.11 L kg⁻¹ d⁻¹) when compared to literature data on domestic ruminants fed on roughage diets (0.58±0.16 L kg⁻¹ d⁻¹). However, there was no significant difference between the two suborders when methane emission was expressed on the basis of digestible neutral detergent fiber intake (92.7±33.9 L kg⁻¹ in camelids vs. 86.2±12.1 L kg⁻¹ in ruminants). This implies that the pathways of methanogenesis forming part of the microbial digestion of fiber in the foregut are similar between the groups, and that the lower methane emission of camelids can be explained by their generally lower relative food intake. Our results suggest that the methane emission of Australia's feral camels corresponds only to 1 to 2% of the methane amount produced by the countries' domestic ruminants and that calculations of greenhouse gas budgets of countries with large camelid populations based on equations developed for ruminants are generally overestimating the actual levels.

Molecular diversity of the foregut bacteria community in the dromedary camel (Camelus dromedarius)

The molecular diversity of the foregut bacterial community in the dromedary camel (Camelus dromedarius) in Central Australia was investigated through comparative analyses of 16S rRNA gene sequences prepared from the foregut contents of 12 adult feral camels fed on native vegetation. A total of 267 full-length 16S rRNA gene clones were examined, with 151 operational taxonomic units (OTUs) identified at a 99% species-level identity cut-off criterion. The prediction of actual diversity in the foregut of the dromedary camel using the Chaol approach was 238 OTUs, while the richness and evenness of the diversity estimated using Shannon index was 4.84. The majority of bacteria in the current study were affiliated with the bacterial phylum Firmicutes (67% of total clones) and were related to the classes Clostridia, Bacilli and Mollicutes, followed by the Bacteroidetes (25%) that were mostly represented by the family Prevotellaceae. The remaining phyla were represented by Actinobacteria, Chloroflexi, Cynophyta, Lentisphaerae, Planctomycetes, Proteobacteria and Sphirochaetes. Moreover, 11 clones of cultivated bacteria were identified as Brevundimonas sp., Butyrivibrio fibrisolvens, Prevotella sp. and Ruminococcus flavefaciens. The novelty in this foregut environment is remarkable where 97% of the OTUs were distantly related to any known sequence in the public database.

Identification and characterisation of the predominant lactic acid-producing and lactic acid-utilising bacteria in the foregut of the feral camel (Camelus dromedarius) in Australia

The camel is emerging as a new and important animal in the Australian livestock industry. However, little is known regarding the microbial ecosystem of the gastrointestinal tract of this ruminant-like animal. This study was carried out to determine the diversity of lactic acid-producing and lactic acid-utilising bacteria in the foregut of the feral camel (Camelus dromedarius) in Australia. Putative lactic acid bacteria were isolated from the foregut contents of camels by culturing on De Man, Rogosa, Sharpe and lactic acid media. Identification of representative isolates was based on the analysis of 16S rRNA gene sequences. Fermentation end products of glucose (i.e. volatile fatty acids and lactate) were also measured in vitro. The key predominant bacteria identified in this study were closely related to Streptococcus bovis, Selenomonas ruminantium, Butyrivibrio fibrisolvens, Lachnospira pectinoschiza and Prevotella ruminicola. The main L-lactate producers were those isolates closely related to S. bovis, S. ruminantium and Lactococcus garvieae, while the efficient lactate utilisers were S. ruminantium-related isolates. D-lactate was produced by isolates closely related to either L. pectinoschiza or S. ruminantium. The predominant bacteria isolated and characterised in this study are identical and/or closely related to those typically found in true ruminants (e.g. S. ruminantium, B. fibrisolvens, S. bovis). In addition, some of the bacteria isolated represent novel species of Lachnospira and Clostridium in the context of lactic acid bacteria from a large herbivorous host. The results from this study have contributed to our understanding and provide opportunities to reduce foregut acidosis in the camel.

Streptococcus bovis causing perforating corneal ulcer

PURPOSE

The purpose of this study was to report the first case of Streptococcus bovis causing a perforating corneal ulcer in a healthy adult.

METHODS

Observational case report.

RESULTS

A healthy 77-year-old man presented with rapidly progressing corneal ulcer, resulting in perforation within 4 days. Preoperative and operative cultures isolated the same organism, S. bovis, susceptible only to vancomycin and ceftriaxone. The patient underwent a successful corneal transplantation, with histopathology revealing full-thickness necrosis and scattered bacteria.

CONCLUSIONS

Although a rare pathogen in ocular infections, we report a case of devastating corneal infection caused by S. bovis and highlight consideration of this pathogen in rapidly progressing corneal ulcers.

Ecology and pathogenicity of gastrointestinal Streptococcus bovis

Streptococcus bovis is an indigenous resident in the gastrointestinal tracts of both humans and animals. S. bovis is one of the major causes of bacterial endocarditis and has been implicated in the incidence of human colon cancer, possibly due to chronic inflammatory response at the site of intestinal colonization. Certain feeding regimens in ruminants can lead to overgrowth of S. bovis in the rumen, resulting in the over-production of lactate and capsular polysaccharide causing acute ruminal acidosis and bloat, respectively. There are multiple strategies in controlling acute lactic acidosis and bloat. The incidence of the two diseases may be controlled by strict dietary management. Gradual introduction of grain-based diets and the feeding of coarsely chopped roughage decrease the incidence of the two disease entities. Ionophores, which have been used to enhance feed conversion and growth rate in cattle, have been shown to inhibit the growth of lactic acid bacteria in the rumen. Other methods of controlling lactic acid bacteria in the ruminal environment (dietary supplementation of long-chain fatty acids, induction of passive and active immune responses to the bacteria, and the use of lytic bacteriophages) have also been investigated. It is anticipated that through continued in-depth ecological analysis of S. bovis the characteristics responsible for human and animal pathogenesis would be sufficiently identified to a point where more effective control strategies for the control of this bacteria can be developed.