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Animals : An Open Access Journal From... Feb 2024The genus is an important group of pathogenic and nonpathogenic Gram-positive anaerobic bacteria with a sporulation capacity and wide distribution in different... (Review)
Review
The genus is an important group of pathogenic and nonpathogenic Gram-positive anaerobic bacteria with a sporulation capacity and wide distribution in different environments, including the gastrointestinal tracts of healthy and diseased animals and humans. Among the pathogenic species of the genus, stands out as a histotoxic agent. It causes significant myonecrosis such as blackleg, a disease with high lethality, especially in young cattle, and is responsible for significant livestock losses worldwide. The pathogenicity of the disease is complex and has not yet been fully elucidated. Current hypotheses cover processes from the initial absorption to the transport and deposition of the agent in the affected tissues. The virulence factors of have been divided into somatic and flagellar antigens and soluble antigens/toxins, which are the main antigens used in vaccines against blackleg in Brazil and worldwide. This review provides important information on the first and current approaches to the agent and its virulence factors as well as a compilation of data on Brazilian studies related to blackleg.
PubMed: 38396606
DOI: 10.3390/ani14040638 -
International Journal of Food... Oct 2023Anaerobic spore-forming bacteria are a continuous threat to the dairy industry due to their ability to withstand processing conditions, such as those during heat...
Anaerobic spore-forming bacteria are a continuous threat to the dairy industry due to their ability to withstand processing conditions, such as those during heat treatment. These ubiquitous microorganisms have ample opportunity for multiple entry points into the milk chain, creating food quality and safety issues. Certain spore-formers, namely bacilli and clostridia, are more problematic due to their ability to spoil dairy products and pathogenicity. In this study, we investigated how milk treatment and milk powder production influenced the composition and survival of anaerobic spore-formers. Samples were obtained on three different days (replicate blocks) during the production of dairy powders and examined in a culture-dependent manner using the most probable number method coupled with 16S rRNA amplicon sequencing and metagenomic analysis of the enriched samples. Results revealed that the milk separation greatly affected the spore-former presence and composition which were detected along the entire production line from raw material to milk powders. Throughout the various points of the production line, the occurrence of species belonging to the Bacillus cereus sensu lato was higher than that of clostridia. Sequence variants (SVs) belonging to the anaerobic spore-forming genus Clostridium were taxonomically assigned to two SVs groups and were detected in all three replicate blocks. A total of 19 metagenome-assembled genomes were recovered from nine enrichments. Four near-complete and two medium-quality genomes were found in raw milk/milk powder samples and further assigned as Clostridium tyrobutyricum and Clostridium diolis, which may constitute a problem in the finished dairy product. In conclusion, our findings highlight spore-formers' importance on dairy quality and may aid in their intervention and control in the dairy production line.
Topics: Animals; Milk; Powders; Hot Temperature; Spores, Bacterial; RNA, Ribosomal, 16S; Anaerobiosis
PubMed: 37356408
DOI: 10.1016/j.ijfoodmicro.2023.110281 -
Microbiology Spectrum Dec 2023Respiration is a fundamental and complex process that bacteria use to produce energy. Despite aerobic respiration being the most common, some bacteria make use of a mode...
Respiration is a fundamental and complex process that bacteria use to produce energy. Despite aerobic respiration being the most common, some bacteria make use of a mode of respiration in the absence of oxygen, called anaerobic respiration, which can yield advantages in adaptation to various environmental conditions. Denitrification is part of this respiratory process ensuring higher respiratory flexibility under oxygen depletion. Here, we report for the first time the evidence of anaerobic growth of spp. under denitrifying conditions, which implies that this genus should be reconsidered as facultative anaerobic. Our study further describes that efficient denitrification is not equally found within the genus, with atypical species showing a greater ability to denitrify, correlated with higher expression of the genes involved, as compared to classical species.
Topics: Bacteria, Anaerobic; Bacteria; Oxygen
PubMed: 37882559
DOI: 10.1128/spectrum.02767-23 -
Microorganisms Sep 2023Fecal microbiota transplantation (FMT) is under investigation for several indications, including ulcerative colitis (UC). The clinical success of FMT depends partly on...
Fecal microbiota transplantation (FMT) is under investigation for several indications, including ulcerative colitis (UC). The clinical success of FMT depends partly on the engraftment of viable bacteria. Because the vast majority of human gut microbiota consists of anaerobes, the currently used aerobic processing protocols of donor stool may diminish the bacterial viability of transplanted material. This study assessed the effect of four processing techniques for donor stool (i.e., anaerobic and aerobic, both direct processing and after temporary cool storage) on bacterial viability. By combining anaerobic culturing on customized media for anaerobes with 16S rRNA sequencing, we could successfully culture and identify the majority of the bacteria present in raw fecal suspensions. We show that direct anaerobic processing of donor stool is superior to aerobic processing conditions for preserving the bacterial viability of obligate anaerobes and butyrate-producing bacteria related to the clinical response to FMT in ulcerative colitis patients, including , , and . The effect of oxygen exposure during stool processing decreased when the samples were stored long-term. Our results confirm the importance of sample conditioning to preserve the bacterial viability of oxygen-sensitive gut bacteria. Anaerobic processing of donor stool may lead to increased clinical success of FMT, which should further be investigated in clinical trials.
PubMed: 37764082
DOI: 10.3390/microorganisms11092238 -
Frontiers in Microbiology 2023The alpine grassland ecosystem is a biodiversity hotspot of plants on the Qinghai-Tibetan Plateau, where rapid climate change is altering the patterns of plant...
The alpine grassland ecosystem is a biodiversity hotspot of plants on the Qinghai-Tibetan Plateau, where rapid climate change is altering the patterns of plant biodiversity along elevational and seasonal gradients of environments. However, how belowground microbial biodiversity changes along elevational gradient during the growing season is not well understood yet. Here, we investigated the elevational distribution of soil prokaryotic communities by using 16S rRNA amplicon sequencing along an elevational gradient between 3,200 and 4,200 m, and a seasonal gradient between June and September in the Qinghai-Tibetan alpine grasslands. First, we found soil prokaryotic diversity and community composition significantly shifted along the elevational gradient, mainly driven by soil temperature and moisture. Species richness did not show consistent elevational trends, while those of evenness declined with elevation. Copiotrophs and symbiotic diazotrophs declined with elevation, while oligotrophs and AOB increased, affected by temperature. Anaerobic or facultatively anaerobic bacteria and AOA were hump-shaped, mainly influenced by moisture. Second, seasonal patterns of community composition were mainly driven by aboveground biomass, precipitation, and soil temperature. The seasonal dynamics of community composition indicated that soil prokaryotic community, particularly Actinobacteria, was sensitive to short-term climate change, such as the monthly precipitation variation. At last, dispersal limitation consistently dominated the assembly process of soil prokaryotic communities along both elevational and seasonal gradients, especially for those of rare species, while the deterministic process of abundant species was relatively higher at drier sites and in drier July. The balance between deterministic and stochastic processes in abundant subcommunities might be strongly influenced by water conditions (precipitation/moisture). Our findings suggest that both elevation and season can alter the patterns of soil prokaryotic biodiversity in alpine grassland ecosystem of Qinghai-Tibetan Plateau, which is a biodiversity hotspot and is experiencing rapid climate change. This work provides new insights into the response of soil prokaryotic communities to changes in elevation and season, and helps us understand the temporal and spatial variations in such climate change-sensitive regions.
PubMed: 37808282
DOI: 10.3389/fmicb.2023.1280011 -
Microbial Biotechnology Nov 2023The global economic burden of microbial corrosion of metals is enormous. Microbial corrosion of iron-containing metals is most extensive under anaerobic conditions.... (Review)
Review
The global economic burden of microbial corrosion of metals is enormous. Microbial corrosion of iron-containing metals is most extensive under anaerobic conditions. Microbes form biofilms on metal surfaces and can directly extract electrons derived from the oxidation of Fe to Fe to support anaerobic respiration. H generated from abiotic Fe oxidation also serves as an electron donor for anaerobic respiratory microbes. Microbial metabolites accelerate this abiotic Fe oxidation. Traditional strategies for curbing microbial metal corrosion include cathodic protection, scrapping, a diversity of biocides, alloys that form protective layers or release toxic metal ions, and polymer coatings. However, these approaches are typically expensive and/or of limited applicability and not environmentally friendly. Biotechnology may provide more effective and sustainable solutions. Biocides produced with microbes can be less toxic to eukaryotes, expanding the environments for potential application. Microbially produced surfactants can diminish biofilm formation by corrosive microbes, as can quorum-sensing inhibitors. Amendments of phages or predatory bacteria have been successful in attacking corrosive microbes in laboratory studies. Poorly corrosive microbes can form biofilms and/or deposit extracellular polysaccharides and minerals that protect the metal surface from corrosive microbes and their metabolites. Nitrate amendments permit nitrate reducers to outcompete highly corrosive sulphate-reducing microbes, reducing corrosion. Investigation of all these more sustainable corrosion mitigation strategies is in its infancy. More study, especially under environmentally relevant conditions, including diverse microbial communities, is warranted.
Topics: Humans; Nitrates; Corrosion; Caustics; Metals; Oxidation-Reduction; Biofilms; Disinfectants
PubMed: 37796110
DOI: 10.1111/1751-7915.14347 -
Journal of Veterinary Science Nov 2023Antibiotic beads are used to treat local bacterial infections by delivering high drug concentrations to infected tissue.
BACKGROUND
Antibiotic beads are used to treat local bacterial infections by delivering high drug concentrations to infected tissue.
OBJECTIVES
This study examined the elution characteristics of metronidazole from metronidazole-calcium sulfate (MCa) and metronidazole-calcium-potassium sulfate (MCaK) beads over 20 days and the antibacterial efficacy of the beads after storage.
METHODS
The MCa and MCaK beads were prepared by mixing 250 mg of metronidazole and 10 g of calcium sulfate hemihydrate with water and a 3% potassium sulfate solution, respectively. The beads were placed in phosphate-buffered saline for the elution study. The metronidazole eluents were determined using high-performance liquid chromatography. The microstructures were examined by scanning electron microscopy (SEM), and the antimicrobial activity was evaluated by a microbioassay.
RESULTS
For the 20-day study, the total amount of metronidazole released was greater in the MCa beads than in the MCaK beads by 6.61 ± 0.48 mg (89.11% ± 3.04%) and 4.65 ± 0.36 mg (73.11% ± 4.38%), respectively. The amounts of eluted drugs from the MCa and MCaK beads were higher than the minimum inhibitory concentration at 0.5 µg/mL against anaerobic bacteria at both 20 days and 14 days. SEM showed that calcium crystals on the outer surface had dissolved after elution, and thinner calcium crystals were prominent in the MCaK beads. The MCa and MCaK beads exhibited antibacterial activity after setting, followed by storage at room temperature or 4°C for 21 days.
CONCLUSIONS
The MCa beads could release more drug than the MCaK beads, but all eluted metronidazole amounts were effective in controlling bacterial infections. Both metronidazole beads could be stored at ambient temperature or in a refrigerator.
Topics: Animals; Metronidazole; Calcium Sulfate; Calcium; Anti-Bacterial Agents; Bacterial Infections
PubMed: 37904636
DOI: 10.4142/jvs.23166 -
Cureus Nov 2023Intra-abdominal complications such as peritoneal abscesses pose significant medical challenges. Over recent years, there has been a heightened focus on refining... (Review)
Review
Intra-abdominal complications such as peritoneal abscesses pose significant medical challenges. Over recent years, there has been a heightened focus on refining treatments for these conditions, such as optimal surgical techniques, drug therapies, and intervention methods. This paper aims to present a comprehensive overview of 10 research studies spanning various countries to highlight recent advancements and findings in the treatment and management of peritoneal abscesses. The paper reviewed 10 trials involving a total of 942 participants, covering diverse methodologies including randomized controlled trials, retrospective analyses, and phase 3 clinical trials. The research spanned countries such as the USA, Finland, Japan, Turkey, India, and China. Key findings included the notable benefits of laparoscopic interventions in appendiceal abscess treatments, which led to quicker recoveries and reduced readmissions compared to conservative approaches. Additionally, certain drug combinations, such as tazobactam/ceftolozane with metronidazole, showcased high clinical efficacy, particularly against resistant bacterial strains. Challenges persist in the early detection of intra-abdominal infections, emphasizing the pivotal role of antimicrobial treatments. Unique therapeutic approaches, like the use of strong acid-electrolyzed water (SAEW) in pediatric appendicitis cases, have proven effective in reducing surgical site infections. Intrabdominal complications such as peritoneal abscesses pose a real challenge. Early detection plays a critical role, which relies on using imaging techniques such as CT scans. Poorly managed mild intra-abdominal diseases can lead to the development of abscesses. Therefore, the implication of highly effective antibiotic combinations such as tazobactam/ceftolozane and metronidazole/ceftriaxone from the start can effectively combat challenging bacterial infections such as Gram-negative and anaerobic bacteria. Surgical procedures remain the most effective method to treat abscesses, and they are usually used as the last resort when drainage, laparoscopy, and other methods fail.
PubMed: 38084178
DOI: 10.7759/cureus.48601 -
Ear, Nose, & Throat Journal Oct 2023To explore the clinical features, diagnosis, and treatment strategies for otogenic brain abscesses (OBA). Clinical data from 10 patients with OBA were analyzed...
To explore the clinical features, diagnosis, and treatment strategies for otogenic brain abscesses (OBA). Clinical data from 10 patients with OBA were analyzed retrospectively. Clinical characteristics, diagnosis, and treatment experiences were summarized. Two were first diagnosed in the Department of Otorhinolaryngology, 5 in Neurosurgery, and 3 in other departments. There were 6 cases of temporal lobe abscess and 4 cases of cerebellar abscesses. Five cases were accompanied by 1 or more intracranial complications. Headache is a common presentation in all cases. The main pathogenic bacteria were anaerobic bacteria. All patients had no previous ear or brain surgery history, and no history of traumatic brain injury, 7 received surgical treatment in the neurosurgery and/or otolaryngology department. Two patients died, the other 8 fully recovered and so were discharged. Diagnosis and treatment of OBA must involve multiple departments. Multidisciplinary consultation (MDT) is crucial to the success of the first OBA diagnosis. The diagnosis and treatment team develops personalized treatment plans by integrating MDT treatment opinions and combining the actual condition of patients, thereby making the diagnosis and treatment of OBA accurate and timely.
PubMed: 37902176
DOI: 10.1177/01455613231205442 -
Journal of Environmental Management Oct 2023As a consequence of the rapidly growing poultry industry, chicken litter is becoming an abundant and problematic waste. Anaerobic digestion of chicken litter can...
As a consequence of the rapidly growing poultry industry, chicken litter is becoming an abundant and problematic waste. Anaerobic digestion of chicken litter can mitigate environmental issues while producing valuable by-products. Recent studies have shown that leach bed reactor (LBR) systems are suitable for processing chicken litter and that anaerobic digestion can be enhanced using biochar. This study investigates the influence of biochar position within an LBR system on anaerobic digestion of chicken litter. Compared to a system without biochar, application of biochar in both the LBR (mixed in with the feedstock or as a layer below the feedstock) and coupled leachate tank (LT) increased methane yield by 6 to 8% at 51 days and accelerated VFA degradation and methane production. More significant differences in methane yield were observed at shorter solid retention times. Biochar mixed in feedstock in addition to a filter in the LT performed best in terms of both methane and hydrogen sulfide production, with a 77% reduction in hydrogen sulfide yield and hydrogen sulfide contents maintained below 500 ppm. The enhanced rates of VFA degradation and methane production when applying biochar in both reactors corresponds with observed differences in the methanogen population. Biochar application in both reactors increased the abundance of Methanobacteriales in digestate and Methanosarcinaceae in leachate compared to the control. Microbial attachment and activity on biochar also increased when mixed in feedstock. Increased diversity of the methanogen population throughout the system, as well as increased activity on biochar, may have facilitated the syntrophic relationship between acetogenic bacteria and methanogens, thus accelerating VFA degradation and methane production. These results suggest mixing biochar in feedstock, in addition to a biochar filter in the LT, to enhance anaerobic digestion of chicken litter in this system.
Topics: Animals; Chickens; Anaerobiosis; Bioreactors; Hydrogen Sulfide; Methane
PubMed: 37348304
DOI: 10.1016/j.jenvman.2023.118404