Bacterial biofilms are complex surface attached communities of bacteria held together by self-produced polymer matrixs mainly composed of polysaccharides, secreted proteins, and extracellular DNAs. ...Bacterial biofilm formation is a complex process and can be described in five main phases: (i) reversible attachment phase, where bacteria non-specifically attach to surfaces; (ii) irreversible attachment phase, which involves interaction between bacterial cells and a surface using bacterial adhesins such as fimbriae and lipopolysaccharide (LPS); (iii) production of extracellular polymeric substances (EPS) by the resident bacterial cells; (iv) biofilm maturation phase, in which bacterial cells synthesize and release signaling molecules to sense the presence of each other, conducing to the formation of microcolony and maturation of biofilms; and (v) dispersal/detachment phase, where the bacterial cells depart biofilms and comeback to independent planktonic lifestyle. Biofilm formation is detrimental in healthcare, drinking water distribution systems, food, and marine industries, etc. As a result, current studies have been focused toward control and prevention of biofilms. In an effort to get rid of harmful biofilms, various techniques and approaches have been employed that interfere with bacterial attachment, bacterial communication systems (quorum sensing, QS), and biofilm matrixs. Biofilms, however, also offer beneficial roles in a variety of fields including applications in plant protection, bioremediation, wastewater treatment, and corrosion inhibition amongst others. Development of beneficial biofilms can be promoted through manipulation of adhesion surfaces, QS and environmental conditions. This review describes the events involved in bacterial biofilm formation, lists the negative and positive aspects associated with bacterial biofilms, elaborates the main strategies currently used to regulate establishment of harmful bacterial biofilms as well as certain strategies employed to encourage formation of beneficial bacterial biofilms, and highlights the future perspectives of bacterial biofilms.
This study focused on providing a holistic solution to biodiesel instability challenges using a fuel additive. Three different samples of the multi-functional fuel additive (MFA 1, MFA 2 and MFA 3) ...were synthesized from abundant lignocellulose-based feedstock. Findings from their property evaluation reveal that 29.67 ± 8.08, 44.67 ± 2.31 and 53.33 ± 8.08% 2,2-Diphenyl-1-picrylhydrazyl (DPPH) radical inhibition with the MFA 1, MFA 2 and MFA 3 respectively, which shows an obvious antioxidation property. Also, findings obtained from the analysis of the additives using differential scanning calorimeter (DSC) reveal a reduction in crystallization temperature of biodiesel by 3.96, 8.79 and 14.25 °C with the MFA 1, MFA 2 and MFA 3 respectively, which signifies a robust anti-freezing property. Furthermore, the additives exhibited antibacterial and antifungal properties against some bacterial and fungal strains that were reported to have negative effects on biodiesel (Bacillus pumilus and Paecilomyces variotii respectively). For instance, the least zones of inhibition of 22.33 ± 0.58and 35.00 ± 5.03 mm were recorded with MFA 1 against the Bacillus pumilus and Paecilomyces variotii respectively using agar well method. Strikingly, biodiesel doped with MFA 2 exhibited improved oxidation stability, lower freezing temperature and strong inhibition against the microbial strains without taking other important properties of biodiesel out of standard specifications.
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•Synthesis of a multi-functional biodiesel additive from bio-based feedstock is reported for the first time.•The synthesized additives are totally miscible in biodiesel and exhibited antioxidative, anti-freezing and antimicrobial properties.•5% vol/vol. dosage of the additive impacted significant increase in oxidation induction temperature of biodiesel by 82 °C.•20% vol/vol. dosage of the additive impacted significant reduction of 8.79 °C in the high melting temperature.
Aedes aegypti
is a crucial vector for many arboviral diseases that cause millions of deaths worldwide and thus is of major public health concern. Crystal (Cry) proteins, which are toxins produced by
...Bacillus thuringiensis
, are structurally organized into three-domains, of which domain II is the most variable in terms of binding towards various toxin receptors. The binding of Cry11Aa to putative receptor such as aminopeptidase-N (APN) is explicitly inhibited by midgut C-type lectins (CTLs). The similarity between the domain II fold of Cry11Aa toxin and the carbohydrate recognition domain in the CTLs is a possible structural basis for the involvement of Cry domain II in the recognition of carbohydrates on toxin receptors. In this study, a site-directed point mutation was introduced into the
A. aegypti
CTLGA9 gene on the basis of molecular docking findings, leading to substitution of the Leucine-6 (Leu-6) residue in the protein with alanine. Subsequently, functional monitoring of the mutated protein was carried out. Unlike the amino acid residues of wild-type CTLGA9, none of the residues of mutant (
m
) CTLGA9 were competed with Cry11Aa for binding to the APN receptor interface. Additionally, ligand blot analysis showed that both wild-type and mutant CTLGA9 had similar abilities to bind to APN and Cry11Aa. Furthermore, in the competitive ELISA in which labeled mutant CTLGA9 (10 nM) was mixed with increasing concentrations of unlabeled Cry11Aa (0–500 nM), the mutant showed no competition with Cry11Aa for binding to APN., By contrast, in the positive control sample of labeled wild type CTLGA9 mixed with same concentrations of Cry11Aa competition between the two ligands for binding to the APN was evident. These results suggest that Leucine-6 may be the key site involved in the competitive receptor binding between CTLGA9 and Cry11Aa. Moreover, according to the bioassay results, mutant CTLGA9 could in fact enhance the toxicity of Cry11Aa. Our novel findings provide further insights into the mechanism of Cry toxicity as well as a theoretical basis for enhancing the mosquitocidal activity of these toxin through molecular modification strategies.
is one of the world's most dangerous mosquitoes, and a vector of diseases such as dengue fever, chikungunya virus, yellow fever, and Zika virus disease. Currently, a major global challenge is the ...scarcity of antiviral medicine and vaccine for arboviruses.
var israelensis (
) toxins are used as biological mosquito control agents. Endotoxins, including Cry4Aa, Cry4Ba, Cry10Aa, Cry11Aa, and Cyt1Aa, are toxic to mosquitoes. Insect eradication by Cry toxin relies primarily on the interaction of cry toxins with key toxin receptors, such as aminopeptidase (APN), alkaline phosphatase (ALP), cadherin (CAD), and ATP-binding cassette transporters. The carbohydrate recognition domains (CRDs) of lectins and domains II and III of Cry toxins share similar structural folds, suggesting that midgut proteins, such as C-type lectins (CTLs), may interfere with interactions among Cry toxins and receptors by binding to both and alter Cry toxicity. In the present review, we summarize the functional role of C-type lectins in
mosquitoes and the mechanism underlying the alteration of Cry toxin activity by CTLs. Furthermore, we outline future research directions on elucidating the
resistance mechanism. This study provides a basis for understanding
resistance, which can be used to develop novel insecticides.
Beneficial root-associated rhizospheric microbes play a key role in maintaining host plant growth and can potentially allow drought-resilient crop production. The complex interaction of ...root-associated microbes mainly depends on soil type, plant genotype, and soil moisture. However, drought is the most devastating environmental stress that strongly reduces soil biota and can restrict plant growth and yield. In this review, we discussed our mechanistic understanding of drought and microbial response traits. Additionally, we highlighted the role of beneficial microbes and plant-derived metabolites in alleviating drought stress and improving crop growth. We proposed that future research might focus on evaluating the dynamics of root-beneficial microbes under field drought conditions. The integrative use of ecology, microbial, and molecular approaches may serve as a promising strategy to produce more drought-resilient and sustainable crops.
Microbial pesticides can be significantly improved by adjuvants. At present, microbial pesticide formulations are mainly wettable powders and suspension concentrations, which are usually produced ...with adjuvants such as surfactants, carriers, protective agents, and nutritional adjuvants. Surfactants can improve the tension between liquid pesticides and crop surfaces, resulting in stronger permeability and wettability of the formulations. Carriers are inert components of loaded or diluted pesticides, which can control the release of active components at appropriate times. Protective agents are able to help microorganisms to resist in adverse environments. Nutritional adjuvants are used to provide nutrients for microorganisms in microbial pesticides. Most of the adjuvants used in microbial pesticides still refer to those of chemical pesticides. However, some adjuvants may have harmful effects on non-target organisms and ecological environments. Herein, in order to promote research and improvement of microbial pesticides, the types of microbial pesticide formulations were briefly reviewed, and research progress of adjuvants and their applications in microbial pesticides were highlighted, the challenges and the future perspectives towards sustainable green adjuvants of microbial pesticides were also discussed in this review.
Bacillus
biocontrol agent(s) BCA(s) such as
Bacillus cereus, Bacillus thuringiensis
and
Bacillus subtilis
have been widely applied to control insects’ pests of plants and pathogenic microbes, improve ...plant growth, and facilitate their resistance to environmental stresses. In the last decade, researchers have shown that, the application of
Bacillus
biocontrol agent(s) BCA(s) optimized agricultural production yield, and reduced disease risks in some crops. However, these bacteria encountered various abiotic stresses, among which ultraviolet (UV) radiation severely decrease their efficiency. Researchers have identified several strategies by which
Bacillus
biocontrol agents resist the negative effects of UV radiation, including transcriptional response, UV mutagenesis, biochemical and artificial means (addition of protective agents). These strategies are governed by distinct pathways, triggered by UV radiation. Herein, the impact of UV radiation on
Bacillus
biocontrol agent(s) BCA(s) and their mechanisms of resistance were discussed.
Insect and mite pests are damaging stressors that are threatening the cultivation of tea plants, which result in enormous crop loss. Over the years, the effectiveness of synthetic pesticides has ...allowed for its prominent application as a control strategy. However, the adverse effects of synthetic pesticides in terms of pesticide residue, environmental contamination and insect pest resistance have necessitated the need for alternative strategies. Meanwhile, microbial pesticides have been applied to tackle the damaging activities of the insect and mite pests of tea plants, and their performances were scientifically adjudged appreciable and environmental friendly. Herein, entomopathogenic microbes that were effective against tea geometrid (
Ectropis obliqua
Prout), tea green leafhopper (
Empoasca onukii
Matsuda), paraguay tea ampul (
Gyropsylla spegazziniana
), tea mosquito bug (
Helopeltis theivora
Waterhouse) and red spider mite (
Oligonychus coffea
Nietner) have been reviewed. The current findings revealed that microbial pesticides were effective and showed promising performances against these pests. Overall, this review has provided the basic and integrative information on the integrated pest management (IPM) tool(s) that can be utilized towards successful control of the aforementioned insect and mite pests.
Graphic abstract
Thuricin 4AJ1, produced by
Bacillus thuringiensis
strain 4AJ1, showed inhibition activity against
Bacillus cereus
0938 and ATCC 10987. It began to appear in the stationary phase and reached its ...maximum activity level of 209.958 U at 18 h against
B. cereus
0938 and 285.689 U at 24 h against
B. cereus
ATCC 10987. Tricine–SDS-PAGE results showed that the partly purified thuricin 4AJ1 was about 6.5 kDa. The molecular weights of the known
B. thuringiensis
bacteriocins and the ones obtained by the two mainstream websites for predicting bacteriocins were inconsistent with the size of the thuricin 4AJ1, indicating that the bacteriocin obtained in this study may have a novel structure. Based on the biochemical properties, the thuricin 4AJ1 activities increased after treatment with proteinase K and lipase II, and were not affected by a-amylase, catalase, α-chymotrypsin VII and α-chymotrypsin II. It was heat tolerant, being active up to 90º C. In the pH 3–10 range, it maintained most of its activity. Finally, the sensitivity of the strain 4AJ1 to commonly used antibiotics was tested. In view of its stability and antibacterial activity, thuricin 4AJ1 may be applied as a food biopreservative.
Graphic abstract
Owing to crowded and unsanitary conditions, internally displaced persons (IDPs) have an increased risk of COVID-19 infection. Adoption of COVID-19 preventive measures among this population is ...premised on accurate information, adequate knowledge, and risk perception. We assessed COVID-19 knowledge and risk perception and investigated the association between risk perception and COVID-19 preventive measures, including vaccination among IDPs in Northeast Nigeria.
We conducted a cross-sectional study during July-December 2022 and sampled 2,175 IDPs using stratified sampling. We utilized a 12-point assessment tool to evaluate COVID-19 knowledge. Participants who scored ≥ 6 points were considered to have adequate knowledge. We used a 30-item Risk Behavior Diagnosis Scale to assess COVID-19 risk perception and evaluated each item on a 5-point Likert scale. Participants were divided into risk perception categories by the median of Likert scale scores. We performed weighted logistic regression analysis to identify factors associated with risk perception. Pearson's chi-squared with Rao-Scott adjustment was used to determine the relationship between risk perception and COVID-19 preventive measures.
Of 2,175 participants, 55.7% were 18-39 years old, 70.9% were females, and 81.7% had no formal education. Among the IDPs, 32.0% (95% CI: 28.8 - 35.0) were considered to have adequate COVID-19 knowledge, and 51.3% (95% CI: 47.8 - 54.8) perceived COVID-19 risk as high. Moreover, 46.3% (95% CI: 42.8 - 50.0) had received one dose of COVID-19 vaccine, and 33.1% (95% CI: 29.8 - 36.0) received two doses. Adequate knowledge (Adjusted Odds Ratio (AOR) = 2.10, 95% CI: 1.46 - 3.03) and post-primary education (AOR = 3.20, 95% CI: 1.59 - 6.46) were associated with risk perception. Furthermore, high risk perception was significantly associated with wearing face masks (χ
= 106.32, p-value < .001), practicing hand hygiene (χ
= 162.24, p-value < .001), physical distancing (χ
= 60.84, p-value < .001) and vaccination uptake (χ
= 46.85, p-value < .001).
This study revealed gaps in COVID-19 knowledge, risk perception, and vaccination uptake but demonstrated a significant relationship between risk perception and COVID-19 preventive practices. Health education and risk communication should be intensified to improve knowledge, elicit stronger risk perception, and enhance COVID-19 preventive practices.
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