Anaerobic Bacteria Research Articles

1,2-DCA biodegradation potential of an aquifer assessed in situ and in aerobic and anaerobic microcosms

Background1,2-dichloroethane (1,2-DCA) biodegradation can occur through aerobic or anaerobic pathways that can be exploited in bioremediation strategies. Bioremediation interventions are site specific and generally based on anaerobic pathways, nevertheless expanding knowledge on proper conditions favoring the biodegradation and especially on 1,2-DCA degrading microorganisms is crucial. In this work the intrinsic biodegradation potential of an aquifer impacted by Chlorinated Aliphatic Hydrocarbons (mainly 1,2-DCA) was evaluated by characterizing the aquifer microbiome across space and time and by setting up biostimulation treatments in microcosms under different aerobic and anaerobic conditions, in parallel.ResultsThe microbial profiling of the aquifer revealed noticeable alpha and beta diversity across the sampling sites within the aquifer and strong fluctuations over time. Surprisingly both the anaerobic and aerobic biostimulation treatments led to the successful removal of 1,2-DCA in microcosms, the enrichment of known 1,2-DCA degraders and the detection of reductive or hydrolytic dehalogenases. Ancylobacter and Starkeya were enriched in aerobic microcosms. Desulfovibrio and Desulfuromonas, known as perchloroethylene degraders, were enriched in anaerobic microcosms, suggesting they could be yet unknown 1,2-DCA respirers.ConclusionsOur results demonstrate the occurrence of both aerobic and anaerobic bioremediation potential in the aquifer despite its negative redox potential. Due to the feasibility of direct oxidation with oxygen insufflation, we propose that an enhanced bioremediation strategy based on direct oxidation of 1,2-DCA could be applied to the contaminated aquifer as an ecofriendly, efficient and cost-effective approach as an alternative to anaerobic biodegradation.

Leveraging Lactobacillus plantarum probiotics to mitigate diarrhea and Salmonella infections in broiler chickens

Anaerobic bacteria, such as Lactobacillus plantarum (LP), are known to play a significant role in maintaining gut health and protecting against enteric pathogens in animals. The present study aimed to develop a safe, affordable, and eco-friendly method for producing LP-based probiotics and evaluate their efficacy in mitigating Salmonella-induced diarrhea in broiler chickens. The study employed three different culture media (MRS, TSB, and Baird Parker) to grow LP, which was then dried using a spray-drying technique to produce a stable probiotic formulation. When administered to broiler chickens, the LP probiotic derived from the MRS medium significantly improved body weight gain (4.147-fold increase over 4 weeks) compared to the other two culture conditions. Importantly, the LP probiotic treatment could substantially reduce the diarrhea index in broilers, with up to an 86.45% improvement in Salmonella-induced enteric infections. The beneficial effects were attributed to the ability of LP to modulate the gut microbiome, enhance the integrity of the intestinal mucosa, and mitigate the pathogenic effects of Salmonella. These findings demonstrate the potential of anaerobic Lactobacillus plantarum as a safe and effective probiotic intervention for controlling enteric diseases and improving production outcomes in poultry farming. The developed method provides a sustainable approach to harness the beneficial properties of this anaerobic bacterium for animal health and welfare.Graphical abstract

Mathematical modeling of biohydrogen production via dark fermentation of fruit peel wastes by Clostridium butyricum NE95

BackgroundBiohydrogen production from agro-industrial wastes through dark fermentation offers several advantages including eco-friendliness, sustainability, and the simplicity of the process. This study aimed to produce biohydrogen from fruit and vegetable peel wastes (FVPWs) by anaerobic fermentative bacteria isolated from domestic wastewater. Kinetic analysis of the produced biohydrogen by five isolates on a glucose medium was analyzed using a modified Gompertz model (MGM). Besides, the feasibility of hydrogen production by Clostridium butyricum NE95 using FVPWs as substrates was investigated.ResultsThe bacterial isolate NE95 was selected as the highest biohydrogen producer with maximum biohydrogen production (Hmax) of 1617.67 ± 3.84 mL/L, Rmax (MGM) of 870.77 mL/L/h and lag phase (λ) of 28.37 h. NE95 was phenotypically and genetically identified as C. butyricum and its 16 S rRNA gene sequence was deposited in the GenBank under the accession number PP581833. The genetic screening of hydrogenase gene clusters indicated the presence of Fe-Fe hydrogenase gene in C. butyricum NE95. C. butyricum NE95 showed the ability to produce biohydrogen from different FVPWs, with watermelon and melon peels being the most promising feedstocks for fermentation. It was revealed that using a mixture (1:1, w/w) of watermelon and melon peels as a substrate for C. butyricum NE95 significantly increased biohydrogen yield with Hmax of 991.00 ± 10.54 mL/L, Rmax of 236.31 mL/L/h, λ of 33.92 h and a high accuracy of R2 (0.997).ConclusionsThe study highlights the effectiveness of C. butyricum NE95 on the valorization of FVPWs and generates a sustainable source of biohydrogen production.

Bengtsoniella intestinalis gen. nov., sp. nov., a member of the family Oscillospiraceae, isolated from the hindgut of the marine herbivorous fish Kyphosus sydneyanus.

A Gram-stain-negative, non-spore-forming, rod-shaped, obligately anaerobic bacterium, designated strain BP47G, was isolated from the hindgut of a silver drummer (Kyphosus sydneyanus) fish collected from the Hauraki Gulf, New Zealand. Phylogenetic analysis based on the 16S rRNA gene sequence of the isolate indicated that it belonged to the family Oscillospiraceae in the phylum Bacillota. The gene sequence of BP47G was most similar to Oscillibacter valericigenes with 95.23% sequence identity. Isolate BP47G grew on agar medium containing mannitol and fish gut fluid as the sole carbon sources. Clear colonies of ~1 mm diameter grew within a week at 20-28 °C (optimum 28 °C) and pH 7.1-8.5 (optimum 8.5). BP47G tolerated the addition to the medium of up to 1% NaCl. Formate and butyrate were the major fermentation products. The major cellular fatty acids were C12:0, C13:0, iso-C14:0, C16:0 and C16:1 cis 7. Genomic analyses comparing BP47G with its closest relatives indicated low genomic relatedness based on the average nucleotide identity, average amino acid identity, percentage of conserved protein and in silico DNA-DNA hybridization. Supported by the phenotypic and taxonomic characteristics observed in this study, a novel genus and species Bengtsoniella intestinalis gen. nov., sp. nov. is proposed for isolate BP47G (=ICMP 24688=JCM 35770).

PHARMACOKINETICS OF METRONIDAZOLE IN GREEN (CHELONIA MYDAS), LOGGERHEAD (CARETTA CARETTA), AND KEMP'S RIDLEY (LEPIDOCHELYS KEMPII) SEA TURTLES AFTER SINGLE ORAL AND INTRAVENOUS DOSES.

Currently there are few antibacterial dosage regimens established to be safe and effective for sea turtles. Pharmacokinetic evaluation of antibiotics is an essential step in establishing accurate dosage guidelines for a particular species. Metronidazole is an antibiotic that is effective against anaerobic bacteria and some protozoa. For most anaerobic bacteria, the minimum inhibitory concentration (MIC) for metronidazole ranges from 0.25 to 4.0 µg/ml. The MIC values for some Clostridium species are up to 8 µg/ml, and for protozoal agents of trichomoniasis (MIC of 0.05 µg/ml), amebiasis, and giardiasis the MIC ranges from 1 to 50 µg/ml. The objective of this study was to determine the pharmacokinetic parameters after administration of metronidazole to aid in the establishment of species-specific dose guidelines in green (Chelonia mydas), loggerhead (Caretta caretta), and Kemp's ridley (Lepidochelys kempii) sea turtles. After administering metronidazole at a dose of 20 mg/kg orally and IV, the pharmacokinetics were very similar for these three species of sea turtles (n = 6 for each species). For both oral and IV routes of administration, plasma metronidazole concentrations were maintained above 8 µg/ml for approximately 24 h and above 4 µg/ml for approximately 48 h; however, plasma concentrations of 8 µg/ml were reached within 5 min only for the IV route, versus 8 h for the oral route.

Deciphering the inhibition mechanisms of microplastics on the full-stage sludge anaerobic digestion via enrichment to anaerobic microbes and toxicity of released compounds.

Increasingly accumulated microplastics (MPs) in sludge could affect the sludge treatment process, while the contributions and mechanisms of MP particles and the released organic matters (MP-DOM) are not fully understood. To fill this gap, this study systematically investigates the effects and mechanisms of MPs on sludge anaerobic digestion. In the presence of MPs, the hydrolysis and acidogenesis of organic matters and methanogenesis all decreased due to the inhibition on the activity of anaerobic microorganisms and key enzymes. Mechanism analysis showed that MPs mainly acted as substrates to enrich anaerobic microorganisms and reduced the abundance and function of free microorganisms in sludge that metabolized organic matters. Moreover, a large amount of organic compounds including various plasticizers (dibutyl phthalate) and chain-scission products (benzoic acid) from physical abrasions of MPs with sludge particles, which made a 50.9-51.6 % contribution to the MP-inhibited sludge anaerobic digestion by the chemical toxicity and generated reactive oxygen species. Owing to the decreased digestion performance, the risk associated with ARGs and pathogenic bacteria increased distinctly. The findings highlight the concerns about MP-derived organic compounds compared to the substrate themselves and suggest the necessity for removing MPs in the sludge of wastewater treatment plants (WWTP).

Dysbiosis of gut microbiota in COVID-19 is associated with intestinal DNA phage dynamics of lysogenic and lytic infection.

This study compared intestinal DNA phage dynamics and gut microbiota changes observed at the onset of coronavirus disease 2019 (COVID-19). The study participants included 19 healthy individuals and 19 patients with severe acute respiratory syndrome coronavirus 2 infection. Significant differences were observed in the diversity of the intestinal DNA virome after the onset of COVID-19 compared with that in healthy individuals. Classification by their tail morphology resulted in the order Caudovirales, a double-stranded DNA phage, accounting for >95% of all participants. In classifying phages based on host bacteria, a decreased number of phages infecting mainly the Clostridia class was observed immediately after the onset of COVID-19 and recovered over time. After the onset of COVID-19, two distinct movement patterns of intestinal phages and their host bacteria were observed: phage- and bacteria-predominant. The abundance of obligate anaerobes, such as Clostridium_sense_strict_1, Fusicatenibacter, and Romboutsia, and the phages hosting these bacteria decreased immediately after the onset of COVID-19, and faster phage recovery was observed compared with bacterial recovery. In contrast, the genus Staphylococcus, a facultative anaerobic bacterium, increased immediately after the onset of COVID-19, whereas the phages infecting Staphylococcus decreased. Furthermore, immediately after the onset of COVID-19, the percentage of lytic phages increased, whereas that of temperate phages decreased. These observations suggest that the gut microbiota dysbiosis observed immediately after the onset of COVID-19 may be linked to phage dynamics that control gut microbiota and may also affect the recovery from dysbiosis.IMPORTANCEBacteriophages infect and replicate with bacteria and archaea and are closely associated with intestinal bacteria. The symbiotic relationship between gut microbiota and bacteriophages is of interest, but it is challenging to study their dynamics in the human body over time. SARS-CoV-2 infection has been reported to alter the gut microbiota, which is involved in gut immune regulation and pathophysiology, although changes in the intestinal phages of patients with SARS-CoV-2 and their dynamic relationship with the gut microbiota remain unclear. SARS-CoV-2 infection, which follows a transient pathological course from disease onset to cure, may provide a reliable model to investigate these interactions in the gut environment. Therefore, this study aimed to elucidate the correlation between gut microbiota and intestinal DNA virome dynamics in COVID-19 pathogenesis. This study found that the dysbiosis observed in SARS-CoV-2 infection involves a growth strategy that depends on the phage or bacterial dominance.

Oxygen as obturation biomaterial in endodontic treatment: development of novel membranous dental restoration system

Complexities in obturation and difficulties in disinfection represent significant issues that render endodontic treatment notably time-consuming. A new perspective is essential to reduce both working time and address these two challenges. To date, none of the established techniques for root canal obturation can assure a perfect seal. Solid materials are not easily manipulated to hermetically fill the intricate branches of the root canal system. Concurrently, anaerobic and facultative anaerobic bacteria, particularly Enterococcus faecalis, are predominant in discussions surrounding endodontic infections. Numerous studies have demonstrated that achieving complete disinfection of Enterococcus faecalis is exceedingly difficult, even with the use of irrigating solutions that possess strong antibacterial properties. Under anaerobic conditions, the invasion efficiency of facultative anaerobes is heightened. If irrigation and disinfection fail to entirely eliminate anaerobes and facultative anaerobes, a novel strategy is required to address the bacteria that persist within the root canal. Oxygen can easily permeate the root canal system, eradicate anaerobes, and inhibit facultative anaerobes from becoming pathogenic. Therefore, employing oxygen as a biomaterial for obturation following appropriate cleaning and shaping procedures is anticipated to address the two primary endodontic issues. This article aims to explore a new potential concept for a dental restoration system that utilizes an oxygen-permeable membrane to reduce the time required for endodontic treatment. The membrane is positioned at the orifice of a duct designed to connect the entire root canal system with ambient air outside the restoration. The function of the membrane is somewhat analogous to the masks used during the COVID-19 pandemic, as it allows for the circulation of oxygen while preventing the passage of fluids, debris, and microorganisms. We hypothesize that the oxygen circulating within the root canal system will also function as a continuously renewing antimicrobial agent.

ANÁLISE DA QUALIDADE DE LEITE EM TANQUES DE ORDENHA MECÂNICA, DE ORDENHA MANUAL E TANQUES COMUNITÁRIOS

This study aims to analyze bacterial contamination in milk produced by three different milking systems: manual, mechanical, and community tanks. The research involved collecting milk samples from rural properties in Presidente Médici, focusing on the count of mesophilic aerobic and facultative anaerobic bacteria. The analysis of results showed that the manual milking system had the highest contamination levels due to greater manipulation and the use of simple equipment. On the other hand, the mechanical milking system exhibited an intermediate level of contamination, while community tanks, which generally face challenges regarding hygiene and management, surprisingly showed lower contamination levels than expected. These findings indicate that proper hygiene and management practices are essential to ensure milk quality, regardless of the milking system used. The study emphasizes the importance of training producers and investing in infrastructure to enhance the competitiveness of Brazilian milk in both the domestic and international markets.

Molecular Study: Nitroreductase Enzyme and Nitroimmidazole Resistance Genes (Nim Genes) Effect on AMR to Metronidazole in Clostridium difficile

Nitroreductase enzymes and Nim genes have been observed to be a factor predisposing to reduced susceptibility to metronidazole in anaerobic bacteria. Therefore, this study was determined the effect of nitroreductase enzymes and nim genes in metronidazole susceptibility in UK C. difficile isolates. Three UK C. difficile ribotypes 027, 001, 106 including metronidazole reduced susceptible (CDRM) and metronidazole susceptible (CDSM) C. difficile strains, and 2 control strains from ribotype 010 (CDRM) and 038 (CDSM) were used. Control strain C. perfringens ATCC 3626 previously identified to be nitroreductase positive, and positive control for nimB which was Bacteroides fragilis strain BF8 was also included in this research. These selected strains were observed for their nitroreductase activity and presence of Nim genes. C. perfringens ATCC 3626 demonstrated nitroreductase activity but was absent in C. difficile control. Three CDRM strains (001 and 106 ribotype) demonstrated nitoreductase activity. None of the CDSM strains analysed showed detectable nitroreductase activity. The nim gene PCR amplification was only observed in the nim positive control strain BF8 (about 400 bp). All samples tested including ribotype 001 027 and 106 CDSM and CDRM strains showed no nimPCR product. In conclusion, despite the nitroreductase result obtained, inconsistencies observed during the assay showed methodology issues, thus using radio labelled metronidazole and monitoring the decline in the radiolabel signal proportional to the level of nitroreduction, maybe a preferred method in correlating nitroreductase activity to the CDRM phenotype. Also, this research observed the absence of nim genes in C. difficile UK ribotypes irrespective of metronidazole susceptibility patterns, depicting the inability of the universal primers for nimA-NimE to amplify a potential nim gene in C. difficile UK ribotypes. The universal primers were previously reported incapable of amplifying nimJ due to a different nucleotide sequence coding for same proteins as the universal primers.

Degradation of logs installed underground for a half century and the microbial communities involved

The use of wood in civil engineering projects is attractive from the perspective of utilizing renewable materials and reducing CO2 emissions. Furthermore, civil engineering presents an appealing opportunity to expand the demand for wood. Wood degradation rates are low in anaerobic environments, such as underground conditions. In this study, the degradation of wood after 55 years in an underground environment was examined by analyzing logs that had been driven underground for a soil stabilization project. Log density was measured and wood cell walls were observed under a microscope to estimate the degree of degradation, and the bacterial and fungal communities living in the sapwood of the logs were examined using a metagenomic approach. The results showed that the wood density was hardly reduced, and that anaerobic cellulolytic bacteria were dominant in the microbial communities in the wood. The degree of wood degradation over 55 years was low, indicating that these logs retained their ground improvement function for at least half a century.

Thermophilic anaerobic ethane oxidation coupled with selenate and selenite reduction

Anaerobic microorganisms are critical in regulating ethane in geothermal environments, where selenate and selenite are common contaminants. Although coupling ethane oxidation with selenate reduction has been demonstrated as feasible, such processes remain poorly explored in geothermal environments. This study addressed this gap by successfully enriching thermophilic anaerobic cultures capable of coupling ethane oxidation with selenate/selenite reduction, achieving selenate and selenite removal rate of 2.7 mg Se/L/d and 2.1 mg Se/L/d, respectively. Metagenomic analysis revealed a novel genus ‘Candidatus Ethanivorans selenatireducens’, which accounted for 16.0 % and 32.6 % of microbial communities in selenate- and selenite-dependent systems, respectively. This microorganism encoded pathways for anaerobic ethane oxidation via fumarate addition and genes required for the sequential reduction of selenate to elemental selenium. These findings unveiled a novel microbial mechanism linking ethane oxidation and selenate reduction in geothermal systems, providing new insights into the biogeochemical interaction between carbon and selenium in thermophilic environments.

The collaboration and competition between indigenous microorganisms and exogenous anaerobic digester sludge in anaerobic treatment of pickled mustard wastewater at different salinities

The highly concentrated pickled mustard wastewater presents significant potential for energy recovery, but the stress effect of high osmotic pressure on cell integrity and activity seriously impedes the methane production by anaerobic microorganisms. The survival ability of indigenous microorganisms (IM) in pickled mustard wastewater supports the establishment of anaerobic treatment. Moreover, inoculation of anaerobic digester sludge is a common start-up strategy. However, the effects of exogenous anaerobic sludge on IM are unclear, especially in hypersaline environment. This research aimed to investigate the influence of exogenous anaerobic sludge on the construction, performance, and microbiota at 3% and 5% salinity. And the research focused on the collaboration and competition between exogenous anaerobic sludge and IM. The neutral community model (which explains the formation and evolution of biological communities) indicated that the interaction between exogenous digester sludge microorganisms and IM dominated community assembly. At 3%, the digester sludge collaborated with IM to increase daily COD reduction and biogas production compared with IM group. However, at 5%, the competitive relationship reduced daily COD reduction and biogas production compared with IM group. This study provides a new perspective for the selection of inoculation strategies for exogenous anaerobic digester sludge under different salinity, in order to realize energy conversion from salinity organic wastewater.

Enhancing simultaneous nitrogen and phosphorus removal using partial nitritation/anammox with an airlift inner-circulation partition bioreactor

The partial nitritation/anammox (PNA)-hydroxyapatite (HAP) process for synchronized nitrogen (N) and phosphorus (P) removal has attracted much attention; however, its use has been restricted by the limited availability of optimal bioreactor configuration and its operational conditions. In the present study, a new single-stage PNA reactor, the airlift inner-circulation partition bioreactor (AIPBR), was continuously operated for 261 days at a fixed hydraulic retention time of 6 h. The results showed that the optimal removal performance (ammonia, 92.77 ± 0.72 %; total N, 76.92 ± 1.78 %; %, total P, 86.57 ± 2.84 %) was achieved at a Ca/P ratio of 4.0 during the operation period; the influent ammonia and P concentrations were maintained at 250 mg/L and 20 mg/L, respectively. The P removal efficiency was 10 % higher than that reported in similar studies, indicating that a highly efficient PNA-HAP process can be successfully achieved using the AIPBR. By enhancing the circulation of the mixture between the inner and outer layers, accelerating the accumulation of ammonia-oxidizing and anaerobic ammonia-oxidizing bacteria, and promoting simultaneous biological autotrophic denitrification and phosphorization, the sludge granulation and HAP crystallization were gradually strengthened by the pH increase inside the sludge particles. Our findings provide a scientific basis for developing next-generation technologies for synchronized N and P removal from wastewater.

Vertical profiles of community and activity of methanotrophs in large lake and reservoir of Southwest China

Microbial methane oxidation plays a significant role in regulating methane emissions from lakes and reservoirs. However, the differences in methane oxidation activity and methanotrophic community between lakes and reservoirs remain inadequately characterized. In this study, sediment and water samples were collected from the large shallow lake (Dianchi) and deep reservoirs (Dongfeng and Hongjiadu) located in karst area, Southwest China. The results indicated that the rates of aerobic oxidation of methane (AeOM) in lake sediment ranged from 7.1 to 27.7 μg g−1 d−1, which was higher than that in reservoirs sediment (1.92 to 11.56 μg g−1 d−1). Similarly, the average AeOM in the water column of lake (104.7 μg L−1 d−1) was much higher than that of reservoirs (46 μg L−1 d−1). The content of sediment organic carbon and dissolved inorganic carbon were important factors that influenced the rates of AeOM in sediment and water column, respectively. 16S rRNA genes sequencing revealed a higher relative abundance of methanotrophs in lake sediments compared to reservoir sediments. The dominant methanotrophic taxa in lake was Methylococcaceae (type Ib), while Methylomonadaceae (type Ia) was predominant in reservoirs. Meanwhile, anaerobic methane-oxidizing microorganisms Candidatus Methylomirabilis and Candidatus Methanoperedens were also abundant in sediments of reservoirs. However, metatranscriptomic analysis revealed that the type I methanotrophs, especially Methylobacter, was most active in the sediment of both lake and reservoir. Water depth and conductivity could be the key controlling factors of the structures of methanotrophic communities in sediment and water column, respectively. Metagenome-assembled genomes suggested that type I methanotrophs exhibited greater motility, as evidenced by a higher number of flagellar assembly genes, while type II methanotrophs demonstrated advantages in metabolic processes such as carbon, phosphorus, and methane metabolism.

Enhanced butanol production through intracellular NADH regeneration in CdSe-C. Acetobutylicumg semi-photosynthetic biohybrid system

Current environmental challenges and energy crises highlight the urgent need for a transition in energy mix. In this study, an innovative semi-photosynthetic biohybrid system that combined light-activated cadmium selenide quantum dots (CdSe QDs) with engineered Gram-positive anaerobic bacteria, Clostridium acetobutylicumg (C. acetobutylicumg), was developed to enhance renewable butanol production. The results demonstrated that CdSe QDs could be biosynthesized intracellularly within C. acetobutylicumg through the introduction of glutathione pathway, without causing significant damage to bacteria. Furthermore, this system showed remarkable tolerance to butanol and weak acids. Under illumination, the biological synthesized CdSe QDs enabled C. acetobutylicumg to achieve a 45.5 % increase in NADH/NAD+ ratio compared to C. acetobutylicumg without CdSe QDs. When utilizing undetoxified rice straw hydrolysate in photo-fermentation, this system achieved a butanol titer of 14.82 g/L and a yield of 0.29 g/g. Overall, this work aims to effectively harness solar energy and biomass resources for sustainable clean biofuel production.

Phytotreatment of tofu effluent using water lettuce (Pistia stratiotes) and potential of biogas production from resultant biomass

Tofu effluent contains a high concentration of organic materials, nutrients, suspended solids and is also low in pH. This research was aimed at applying phytotreatment using floating plant species of Pistia stratiotes to polish tofu effluent before final discharge into water bodies while also producing biogas from the resultant biomass after treatment. A range-finding test (RFT) was conducted to determine the initial concentration to be treated and resulted in 10 % tofu effluent. Phytotreatment was conducted for a period of 14 days, focusing on the removal of organic matter and nutrient contents. After 14 days of treatment, P. stratiotes were able to remove total suspended solids (TSS) by 88 %, ammonia by 42.3 %, phosphate by 50 %, chemical oxygen demand (COD) by 84 %, and biological oxygen demand (BOD) by 95 %, significantly higher as compared to control. Phytotreatment was able to stabilize pH to a neutral value, and P. stratiotes were able to transfer oxygen from air to the rhizosphere area. The maximum daily production of biogas using the plant's biomass was higher as compared to the control; however, the overall biogas accumulation was significantly lower during the 45 days of observation. Further biomass pretreatment was suggested before digestion to obtain higher biogas production since the cellulose, hemicellulose, and lignin content inside the plant biomass were subjected to being hardly degraded by the anaerobic microorganisms.

Case report: Relaps of Streptococcus suis infection in patient with Meningoencephalitis at Prof. Ngoerah Hospital, Bali

Background: S. suis is a facultative anaerobic Gram-positive bacterium that causes human infection. It is a primary health problem in the swine industry. Ceftriaxone is a therapeutic option for meningitis besides Ampicillin. Recently, the incidence of resistance to ceftriaxone was reported. The recurrence of S. suis in this patient is thought to be caused by ceftriaxone resistance due to inadequate initial therapy. Case Presentation: A 43-year-old male patient came to the ER with headaches in the head and neck. The patient had a history of meningitis due to S. suis twice before. While in the ER, the patient was given ceftriaxone while awaiting culture results. Blood cultures showed S. suis infection using VITEK 2 COMPACT (Biomeriuex®) and ceftriaxone resistance. The patient was successfully managed with Ampicillin following these culture results, leading to good outcomes. Discussion: S. suis is a gram-positive bacterial pathogen in pigs that can cause severe human infection, including meningitis, septicemia, endocarditis and deafness the most common complications. The patient experienced three relapses due to S. suis. On the third visit, blood culture results identified ceftriaxone-resistant S. suis. The patient's recurrent relapses could be attributed to several factors, including inadequate antibiotic administration, antibiotic resistance, weak immune system, contact with the source of infection and environmental variables, highlighting the complexity and challenges in treating S. suis infection. Conclusion: The use of antibiotics in relapse cases has the potential to cause antibiotic resistance, so it’s necessary to make guidelines for antibiotic therapy in S. suis infection to prevent recurrent infections.

Foraminifera and geomicrobiology as indicators of the environmental recovery in a mangrove affected by oil spills in the Guanabara Bay (Brazil)

Foraminifera could be used as indicators to evaluate the impacts of oil spills because the crude oil causes several disturbances on the development and reproduction of the species. However, little is known about the relationship between mangrove species and this pollutant. Foraminiferal assemblages were studied in 22 surface sediment samples collected from a mangrove in Guanabara Bay (Brazil) that was severely impacted by an oil spill six years earlier. The foraminiferal responses to the environmental stress helped to determine the most degraded areas. Elevated concentrations of aromatic compounds and potentially bioavailable heavy metals, with contamination levels up to nine times higher compared to the pre-industrial period in the Guanabara Bay. The dominance of anaerobic bacteria, and high esterase enzyme activity (ESTE) suggest that the bacterial community is metabolizing the hydrocarbons in the sediments. Despite these stressors, density and diversity of living foraminifera are comparable to values observed in less impacted Brazilian mangroves. Species distribution patterns reveal an environmental gradient across the mangrove with numerous species increasing their relative abundance towards the areas topographically lower and with higher levels of pollutants and ESTE. Specifically, Caronia exilis, Tiphotrocha comprimata, Ammobaculites exiguus, Textularia paranaguaensis, Ammotium cassis, Ammobaculites dilatatus, Polyssaccamina hipohalina, Siphotrochammina lobata, Ammonia tepida, Ammotium morenoi, Miliammina fusca, Entzia macrescens, Trochammina squamata and Paratrochammina clossi are inferred as pollution-tolerant taxa. This integrated geochemical, microbiological and ecological approach applied to assess the sediment quality in a complex ecosystem has important implications for the use of living foraminifera in recovery stage assessments and biomonitoring plans.

Comparative evaluation of BacT/ALERT VIRTUO and BACTEC FX400 blood culture systems for the detection of bloodstream infections.

Bloodstream infections (BSI) pose significant threats to patient health, necessitating timely and accurate diagnostics to reduce mortality and morbidity. This study aimed to evaluate the clinical performance of the BacT/ALERT VIRTUO blood culture system with FANPlus bottles compared to the BACTEC FX400 system in detecting bloodstream pathogens. A total of 1,772 blood specimens were collected from various hospital wards. Specimen selection criteria were based on clinical suspicion of bloodstream infections, ensuring the inclusion of relevant and representative patient samples. These blood samples, collected from the same suspected sepsis patients, were cultured in parallel using both the BacT/ALERT VIRTUO and BACTEC FX400 systems. The diagnostic efficiency of both systems, including detection rates, time to detection (TTD), and sensitivity across different bacterial species, was assessed. In various application scenarios, the VIRTUO system demonstrates a higher positive detection rate, whether in the intensive care unit (ICU) (8.5% vs 6.4%, P = 0.028) or in general wards. Additionally, for different types of bacteria, the TVIRTUO system exhibits superior detection rates for anaerobic bacteria (5.9% vs 3.2%, P < 0.001) and aerobic bacteria (9.1% vs 7.2%, P = 0.043). Furthermore, it boasts a shorter median TTD of 14 hours compared to 16 hours, and a higher sensitivity for Gram-positive bacteria (2.8% vs 1.6%, P < 0.001). These findings emphasize VIRTUO's effectiveness in enhancing diagnostic accuracy, achieving faster time to detection, and expanding the spectrum of detected organisms, thereby facilitating the quicker initiation of appropriate therapies, supporting precise clinical decision-making, and ultimately improving patient outcomes.IMPORTANCEOur study conducted a critical evaluation of advanced blood culture technologies for managing bloodstream infections (BSI). A distinctive strength of our research is the large sample size and the concurrent testing of the same patients with two systems, a methodology rarely achieved in other studies. BSIs present severe health threats, necessitating prompt and accurate diagnostics to mitigate morbidity and mortality. The BacT/ALERT VIRTUO system, in comparison to the BACTEC FX400 system, demonstrated superior detection capabilities, emphasizing the critical role of advanced diagnostics in clinical settings.