Category Archives: Journal of Applied Microbiology

Freshwater mussels and host fish gut microbe community composition shifts after agricultural contaminant exposure

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Abstract

Aims

We examined the effects of a mixture of contaminants found in agricultural watersheds on the gut microbiota and physiology of both the freshwater mussel Lampsilis cardium, and L. cardium host fish Micropterus salmoides.

Methods and results

Lampsilis cardium and M. salmoides were exposed to three concentrations of agricultural contaminants for 60 days (observing behaviour daily) before being sampled for gut microbiota analyses. DNA was extracted from the gut samples, amplified via PCR, and sequenced using the Illumina Mi-Seq platform. Only L. cardium guts had differing microbiota across treatments, with an increase in potentially pathogenic Aeromonas. We also provide novel evidence of a core microbiota within L. cardium and M. salmoides. In terms of physiology, female L. cardium exhibited a decrease in movement and marsupial gill display in contaminant exposures.

Conclusions

Exposure to contaminants from agricultural watersheds may affect population recruitment within freshwater mussel communities over time. Specifically, increased pathogenic micro-organisms and altered behaviour can reduce the likelihood of glochidia dispersal.

Significance and impact of the study

This study supports emerging research that contaminants found in agricultural watersheds may be a factor in freshwater mussel population declines. It also provides novel evidence that unionids have a core gut microbiota.

A novel dibenzofuran from endophytic fungus Mycosphaerella nawae preferentially inhibits CD4+ T cell activation and proliferation

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Abstract

Aim

To obtain promising immunosuppressants from endophytic fungus.

Methods and Results

The endophytic fungus Mycosphaerella nawae (ZJLQ129) was isolated from the plant Smilax china L. and its secondary metabolites extracted and fractionated through column chromatography. The metabolites were further modified by a derivatization reaction with ammonium hydroxide. After isolation and derivatization, a new dibenzofuran named as (+)isomycousnine enamine (iME) was obtained. The structures of the derivatives were determined based on chemical evidences and extensive spectroscopic methods including 2D-NMR, DEPT and HRESI-MS spectra. The immune activities of iME were first evaluated on the proliferation and cytokines (IL-2 and IFN-γ) production of T and B cells by using MTT and ELISA methods respectively. Then, its effects on the proliferation of T-cell subsets (CD4+ and CD8+ T cells), as well as CD25 and CD69 expressions were also determined by flow cytometry. Finally, by using Cytometric Bead Array (CBA), the impacts of iME on the secretion of Th1/Th2/Th17 cytokines from purified CD4+ T cells were assayed. The results showed that iME not only selectively suppressed the immune responses of T cells, but also preferentially inhibited the activation and proliferation of CD4+ T cells.

Conclusion

A novel dibenzofuran derived from endophytic fungus Mycosphaerella nawae preferentially inhibits CD4+ T-cell activation and proliferation.

Significance and Impact of the Study

This work obtained iME, a new dibenzofuran derived from endophytic fungus. iME has the capacity to inhibit CD4+ T-cell activation and therefore is a novel potential immunosuppressant for development in the future.

Simple and field amenable loop‐mediated isothermal amplification‐lateral flow dipstick assay for detection of west Nile virus in human clinical samples

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Abstract

Aim

West Nile encephalitis caused by infection with the West Nile virus (WNV) is endemic in many regions of the world and is a global public health threat. The aim of this report was to develop a method using colorimetry-based reverse-transcription loop-mediated isothermal amplification (cRT-LAMP) and RT-LAMP combined with lateral-flow dipstick (LFD) for rapidly detecting WNV in low-infrastructure settings.

Methods and Results

The primers for the cRT-LAMP and RT-LAMP-LFD assays were designed based on env gene of the WNV. Primers concentration, temperature and time were optimized for cRT-LAMP and RT-LAMP-LFD. The diagnostic performance of the cRT-LAMP and RT-LAMP-LFD assays was evaluated using human serum samples from 110 patients who were clinically suspected to be infected with WNV. The RT-LAMP was performed in a heating block at 63°C for 40 min. The LAMP amplicons were visible in the lateral-flow dipstick within 5 min. The detection limit of the developed cRT-LAMP and RT-LAMP-LFD assays was 10 copies and this assay showed a high degree of specificity for WNV. Compared with quantitative real-time RT-PCR assay, the kappa value of cRT-LAMP and RT-LAMP-LFD were 0.970.

Conclusions

These results showed that the newly developed WNV-specific cRT-LAMP and RT-LAMP-LFD assays can be employed as an alternative method for screening of WN-suspected human samples. The results revealed that the assay could potentially identify the virus without interference from human serum samples. Collectively, all results revealed that cRT-LAMP and RT-LAMP-LFD assays offer a suitable field-based diagnosis of WNV.

Significance and Impact of the Study

The cRT-LAMP and LAMP-LFD platform for the detection of WNV is rapid, accurate and simple-to-perform. Our present method has not only a short turnaround time but also avoided cross-contamination problem. Moreover, the use of simple lateral flow dipsticks broadens its application potential for the point-of-care use in resource-limited settings during outbreak situations. To the best of our knowledge, this is the first report for the development of cRT-LAMP and LAMP-LFD assays for rapid, simple, specific and sensitive detection of WNV using human clinical samples and EvaGreen dye.

Beneficial effects of fermented barley extracts on inflammatory status and gut microbiota in high‐fat diet‐induced obese rats

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Abstract

Aims

To explore how fermented barley extracts could affect obesity-associated inflammatory responses to ameliorate high-fat diet (HFD)-induced obesity, and investigate whether their anti-inflammatory properties were affected by modulating the gut microbiota.

Methods and Results

Twenty-four male rats were assigned randomly to three groups for 8 weeks. Inflammatory status and gut microbiota in HFD-induced obese rats were measured by enzyme linked immunosorbent assay and 16sRNA sequencing technology. The dietary supplementation of Extract of fermented barley with L. plantarum JDM1 (LFBE) reduced HFD-induced obesity and improved insulin sensitivity. LFBE significantly decreased the levels of lipopolysaccharide (LPS) and pro-inflammatory cytokines (tumour necrosis factor-α, interleukin [IL]-6, IL-1β, monocyte chemotactic protein-1), and increased anti-inflammatory cytokines (IL-10) in serum. In addition, LFBE suppressed the activation of nuclear factor-κB (NF-κB) by inhibiting the inhibitor of NF-κB alpha degradation and phosphorylation of JNK/p38 mitogen-activated protein kinases in adipose tissue. Combined with changes in gut microbiota, these results illustrated that LFBE treatment markedly decreased the proportion of the LPS-producing opportunistic pathogens and increased the proportion of Bifidobacterium.

Conclusions

Administration of LFBE has beneficial effects on ameliorating HFD-induced obesity and insulin resistance, lessening HFD-induced gut microbiota dysbiosis and pro-inflammatory cytokines secretion.

Significance and Impact of this Study

The results suggest that fermented barley extracts may be a useful functional compound and beneficial to improve inflammatory status and gut microflora.

Assessing some Cladosporium species in the biodegradation of petroleum hydrocarbon for treating oil contamination

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Abstract

Aim

Biodegradation is a cost-effective and eco-friendly treatment for oil-contaminated materials using microorganisms. Bacteria and fungi can degrade petroleum by using it as an energy source and this may provide an enormous scope to remediate soils contaminated with petroleum and oil. This study aimed to assess the biodegradation of petroleum hydrocarbons by certain Cladosporium species.

Methods and results

By using traditional and spectroscopic assessment analysis, qualitative screening was carried out using Cladosporium spores isolated from air and cultured on mineral salt medium supplemented with petroleum hydrocarbon as the sole carbon source, followed by quantitative assessment using gas chromatography–mass spectroscopy. Nineteen Cladosporium strains from a total of 212 isolates exhibited remarkable capability to degrade petroleum hydrocarbon, representing four species (C. herbarum, C. macrocarpum, C. sphaerospermum, and C. cladosporioides). The results were expressed in terms of biodegradation percentage and optical density of hydrocarbon using a standard calibration curve. The highest reduction of petroleum hydrocarbon was observed with five Cladosporium strains belonging to two species (C. sphaerospermum and C. cladosporioides).

Conclusion

This study succeeded in isolating several Cladosporium strains (from the air) with a high ability to degrade crude oil that can be used as biological agents to control petroleum pollution in soils and seas. The addition of a surfactant (Tween 80) enhanced the degradation of crude oil reaching a final concentration of 0.4%. Based on these results, the present study could indicate some unique prospects in the field of bioremediation and biodegradation of petroleum-contaminated soil.

Significance and impact of study

This study gives unique prospects in the field of bioremediation and biodegradation of petroleum-contaminated soil.

Comparison of Monkeypox virus genomes from the 2017 Nigeria outbreak and the 2022 outbreak

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Abstract

Aims

The current Monkeypox virus (MPX) outbreak is not only the largest known outbreak to date caused by a strain belonging to the West-African clade, but also results in remarkably different clinical and epidemiological features compared to previous outbreaks of this virus. Here, we consider the possibility that mutations in the viral genome may be responsible for its changed characteristics.

Methods and Results

Six genome sequences of isolates from the current outbreak were compared to five genomes of isolates from the 2017 outbreak in Nigeria and to two historic genomes, all belonging to the West-African clade. We report differences that are consistently present in the 2022 isolates but not in the others. Although some variation in repeat units was observed, only two were consistently found in the 2022 genomes only, and these were located in intergenic regions. A total of 55 single nucleotide polymorphisms were consistently present in the 2022 isolates compared to the 2017 isolates. Of these, 25 caused an amino acid substitution in a predicted protein.

Conclusions

The nature of the substitution and the annotation of the affected protein identified potential candidates that might affect the virulence of the virus. These included the viral DNA helicase and transcription factors.

Significance

This bioinformatic analysis provides guidance for wet-lab research to identify changed properties of the MPX.

Decontamination efficacy of common liquid disinfectants against non‐spore‐forming biological agents in soil matrices

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Abstract

Aims

The purpose of this study was to evaluate decontamination efficacy, within three soil types, against Yersinia pestis, Burkholderia pseudomallei, and the Venezuelan Equine Encephalitis virus (VEEV).

Methods and Results

One of three liquid disinfectants (dilute bleach, Virkon-S or Klozur One) was added to three soil types (sand, loam, or clay) and allowed contact for four pre-spike durations: 0, 15, 30 and 60 min. Y. pestis, B. pseudomallei, or VEEV was then spiked into the soil (10 microliters or approx. 1 × 107 CFU or PFU into 1 g soil) and decontamination efficacy assessed at post-spike contact times of 10 or 60 min at ambient environmental conditions. Across all soil types, sandy soil resulted in the least quenching to all three disinfectants tested as shown by sustained decontamination efficacy across all pre-spike and post-spike timepoints. Clay and loam soil types exhibited quenching effects on the hypochlorite and peroxygen based disinfectants (dilute bleach and Virkon S) and in general resulted in decreased efficacy with increased pre-spike contact time. The sodium persulfate (Klozur One) performance was the most consistent across all soil types and pre-spike contact times, resulting in greater efficacy with increased post-spike time.

Conclusions

Liquid disinfectants can provide high levels of decontamination in soil for both viral and non-spore-forming bacterial select agents. Hypochlorite and peroxygen based disinfectants used in soils containing higher organic content (loam or clay) may require extended contact times or re-application of liquid disinfectant, in as little as 15 min of application, to achieve a 6-log reduction.

Significance and Impact of the Study

These results provide information for the performance of three disinfectants in soil against non-spore-forming select agents. These data may aid response decision makers following a biological contamination incident by informing the selection of disinfectant as well as the re-application time to achieve effective site remediation.

Microbial incubations of 8‐phenyloctanoic acid and furan fatty acids in rumen fluid

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Abstract

Aims

The digestive tract of ruminants is specialized in the digestion of various plant components. One of the largest parts of the stomach is the so-called rumen, which contains a large number of micro-organisms that may degrade or modify fatty acids, for example by β-oxidation, chain elongation and/or hydrogenation.

Methods and Results

Here we performed incubation experiments with less common fatty acids by in vitro incubations with rumen fluid of fistulated cows for 24 h. Sample extracts were analysed by gas chromatography with mass spectrometry. As substrates, we selected one phenyl fatty acid and four furan fatty acids (FuFAs). All studied fatty acids were degraded by β-oxidation (two or three chain-shortening steps) while chain elongation or saturation of the aromatic part (terminal phenyl or central furan moiety) was not observed in any case.

Conclusions

The percentage of β-oxidation products was low, especially in the case of the FuFAs. This could be due to the rather long carbon number of FuFAs (19–22 carbon atoms). In addition, compound-specific differences in the degradation rates were observed in our experiments.

Significance and Impact of the Study

Our results produce evidence that FuFAs, which are valuable antioxidants that are known to be present in various feed items of the cow, can be effectively passed on the rumen into the milk.

Effects of supplementing with Humulus scandens on the growth performance and gut microbiota in piglets

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Abstract

Aims

This study was conducted to evaluate the effects of feeding Humulus scandens (Hu) on growth performance and gut microbiota in piglets.

Methods and Results

A total of 120 piglets were allocated to four dietary treatments (1) CON, basal diet; (2) T1, basal diet + 2.0% Hu; (3) T2, basal diet + 2.8% Hu and (4) T3, basal diet + 3.6% Hu. The results showed that dietary H. scandens supplementation increased the final body weight and average daily gain. Furthermore, H. scandens supplementation in T1 groups increased the content of total protein, globulin and IgG in serum and the apparent digestibility of crude protein. Gut microbiota analysis showed that H. scandens treatment in T1 groups increased the abundances of Lactobacillus, Ruminococcaceae, Enterococcus and Pseudomonas in cecum content.

Conclusions

These findings suggested that dietary H. scandens supplementation improved the growth performance, immunological function and nutrient apparent digestibility as well as modulating the gut microbiota in piglets.

Significance and Impact of the Study

This study contributed to developing new feed resources and might provide an alternative strategy for growth promotion in piglets.

Photocatalytic and biological activities of green synthesized SnO2 nanoparticles using Chlorella vulgaris

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Abstract

Aims

To produce tin oxide (SnO2) nanoparticles (NP) with microalga for use in azo dye-polluted wastewater treatment and to optimize the conditions to synthesize as small NPs as possible.

Methods and Results

The green microalga Chlorella vulgaris mediated NPs were synthesized after an optimization process utilizing the statistical response surface methodology (RSM). The optimized synthesis conditions were 200 W microwave power, 0.5 mM SnCl2 concentration and 200°C calcination temperature. Methyl orange (MO) was studied for its photocatalytic degradation with UV. Antibacterial activity against four pathogenic bacteria was studied using the well diffusion method. Cytotoxicity was measured using the MMT assay with lung cancer cell line A549, and antioxidant activity using DPPH radical scavenging. Following the optimization of their production, the produced crystalline SnO2 NPs were on average 32.2 nm (by XRD) with a hydrodynamic size of 52.5 nm (by LDS). Photocatalytic degradation of MO under UV was nearly complete (94% removal) after 90 min and the particles could be reused for 5 cycles retaining 80% activity. The particles had antibacterial activity towards all five tested bacterial pathogens with the minimum inhibitory concentrations ranging from 22 to 36 μg/ml. The minimum bactericidal NP concentration varied between 83 and 136 μg/ml. Antioxidant activity was concentration dependent. A cytotoxicity was determined towards A549 cells with an LD50 of 188 μg/ml after 24 h of incubation, a concentration that is much higher than the active concentration for dye removal ranging from 22 to 36 μg/ml.

Conclusions

After optimization, SnO2 nanoparticles produced with C. vulgaris displayed high photocatalytic activity at concentrations below their antibacterial and cytotoxic activities.

Significance and Impact of the study

The SnO2 nanoparticles produced with the help of microalgae are suitable for the removal of MO dye from wastewater. Further applications of this green technology can be expected.