Potential Use Of Bacteria Research Articles

Microbiota Variation Across Life Stages of European Field-Caught Anopheles atroparvus and During Laboratory Colonization: New Insights for Malaria Research.

The potential use of bacteria for developing novel vector control approaches has awakened new interests in the study of the microbiota associated with vector species. To set a baseline for future malaria research, a high-throughput sequencing of the bacterial 16S ribosomal gene V3-V4 region was used to profile the microbiota associated with late-instar larvae, newly emerged females, and wild-caught females of a sylvan Anopheles atroparvus population from a former malaria transmission area of Spain. Field-acquired microbiota was then assessed in non-blood-fed laboratory-reared females from the second, sixth, and 10th generations. Diversity analyses revealed that bacterial communities varied and clustered differently according to origin with sylvan larvae and newly emerged females distributing closer to laboratory-reared females than to their field counterparts. Inter-sample variation was mostly observed throughout the different developmental stages in the sylvan population. Larvae harbored the most diverse bacterial communities; wild-caught females, the poorest. In the transition from the sylvan environment to the first time point of laboratory breeding, a significant increase in diversity was observed, although this did decline under laboratory conditions. Despite diversity differences between wild-caught and laboratory-reared females, a substantial fraction of the bacterial communities was transferred through transstadial transmission and these persisted over 10 laboratory generations. Differentially abundant bacteria were mostly identified between breeding water and late-instar larvae, and in the transition from wild-caught to laboratory-reared females from the second generation. Our findings confirmed the key role of the breeding environment in shaping the microbiota of An. atroparvus. Gram-negative bacteria governed the microbiota of An. atroparvus with the prevalence of proteobacteria. Pantoea, Thorsellia, Serratia, Asaia, and Pseudomonas dominating the microbiota associated with wild-caught females, with the latter two governing the communities of laboratory-reared females. A core microbiota was identified with Pseudomonas and Serratia being the most abundant core genera shared by all sylvan and laboratory specimens. Overall, understanding the microbiota composition of An. atroparvus and how this varies throughout the mosquito life cycle and laboratory colonization paves the way when selecting potential bacterial candidates for use in microbiota-based intervention strategies against mosquito vectors, thereby improving our knowledge of laboratory-reared An. atroparvus mosquitoes for research purposes.

The potential of nanomaterials associated with plant growth-promoting bacteria in agriculture.

The impacts of chemical fertilizers and pesticides have raised public concerns regarding the sustainability and security of food supplies, prompting the investigation of alternative methods that have combinations of both agricultural and environmental benefits, such as the use of biofertilizers involving microbes. These types of microbial inoculants are living microorganisms that colonize the soil or plant tissues when applied to the soil, seeds, or plant surfaces, facilitating plant nutrient acquisition. They can enhance plant growth by transforming nutrients into a form assimilable by plants and by acting as biological control agents, known as plant growth-promoting bacteria. The potential use of bacteria as biofertilizers in agriculture constitutes an economical and eco-friendly way to reduce the use of chemical fertilizers and pesticides. In this context, nanotechnology has emerged as a new source of quality enrichment for the agricultural sector. The use of nanoparticles can be an effective method to meet the challenges regarding the effectiveness of biofertilizers in natural environments. Given the novel sustainable strategies applied in agricultural systems, this review addresses the effects of nanoparticles on beneficial plant bacteria for promoting plant growth.

The Oral Microbiome and Cancer.

There is mounting evidence that members of the human microbiome are highly associated with a wide variety of cancer types. Among oral cancers, oral squamous cell carcinoma (OSCC) is the most prevalent and most commonly studied, and it is the most common malignancy of the head and neck worldwide. However, there is a void regarding the role that the oral microbiome may play in OSCC. Previous studies have not consistently found a characteristic oral microbiome composition associated with OSCC. Although a direct causality has not been proven, individual members of the oral microbiome are capable of promoting various tumorigenic functions related to cancer development. Two prominent oral pathogens, Porphyromonas gingivalis, and Fusobacterium nucleatum can promote tumor progression in mice. P. gingivalis infection has been associated with oro-digestive cancer, increased oral cancer invasion, and proliferation of oral cancer stem cells. The microbiome can influence the evolution of the disease by directly interacting with the human body and significantly altering the response and toxicity to various forms of cancer therapy. Recent studies have shown an association of certain phylogenetic groups with the immunotherapy treatment outcomes of certain tumors. On the other side of the coin, recently it has been a resurgence in interest on the potential use of bacteria to cure cancer. These kinds of treatments were used in the late nineteenth and early twentieth centuries as the first line of defense against cancer in some hospitals but later displaced by other types of treatments such as radiotherapy. Currently, organisms such as Salmonella typhimurium and Clostridium spp. have been used for targeted strategies as potential vectors to treat cancer. In this review, we briefly summarize our current knowledge of the role of the oral microbiome, focusing on its bacterial fraction, in cancer in general and in OSCC more precisely, and a brief description of the potential use of bacteria to target tumors.

Bacteria Affect Plant-Mite Interactions Via Altered Scent Emissions.

Epiphytic bacteria have been shown to affect the composition of volatiles released by plants and as a consequence the behavior of other organisms towards the plant, such as herbivores and/or pathogens. In this study, we explored the effects of inoculation with three bacterial strains, namely Pseudomonas syringae, Pantoea ananatis, and Pseudomonas putida, on the composition of leaf volatile organic compounds (VOCs) emitted by bean plants (Phaseolus vulgaris L.). In addition, we examined responses of the two-spotted spider mite (Tetranychus urticae) to VOCs by measuring leaf damage and oviposition of female adults after bacterial inoculation. Colonized bean plants emitted different VOCs depending on the bacterial inoculum. The quantities of volatiles 1-undecanol and (Z)-3-hexen-1-ol significantly increased after P. syringae inoculation, while methyl salicylate and anisole increased in response to P. ananatis. T. urticae females preferred control plants over plants inoculated with P. syringae or P. putida in olfactometer assays, while no particular preference was recorded in the presence of P. ananatis. Furthermore, leaf damage caused by spider mites was 3-fold lower in plants inoculated with P. syringae than in control plants and plants inoculated with P. ananatis. Subsequently, the number of eggs laid on leaves inoculated with P. syringae was significantly lower than on those inoculated with P. ananatis or on the control ones. Moreover, a significantly higher number of spider mites selected methyl salicylate odor source over 1-undecanol, in a two-choice bioassay. The results demonstrate the bacterial involvement in plant-arthropod interactions and suggest further investigation on the potential use of bacteria as biocontrol agents in agriculture.

Potential use of bacteria collected from human hands for textile dye decolorization

We obtained dye-decolorizing bacteria from the hands of ordinary people with an efficiency of approximately 40%. The bacteria were classified into the azo dye-decolorizing group and anthraquinone dye-decolorizing group. The former were capable of decolorizing real textile wastewater, whereas the latter could achieve only partial decolorization. These bacterial strains can potentially be applied to assess the major types of dyes in textile wastewater and dye-polluted rivers. The azo dye-decolorizing bacterial strain degraded Congo red into its intermediates and then further degraded phenyl compounds. Interestingly, the azo dye-decolorizing bacterial strain produced a significant amount of protein (20–60 mg L−1), which correlated with the dye-decolorization rate. We further identified cell density as the main factor affecting stabilization of the dye-decolorization reaction. In summary, human hands are a readily accessible source from which to collect dye-decolorizing bacteria that can be used to treat textile wastewater and to remediate environmental pollution sites.

Architects of nature: growing buildings with bacterial biofilms.

SummaryIn his text ‘On Architecture’, Vitruvius suggested that architecture is an imitation of nature. Here we discuss what happens when we begin using nature in architecture. We describe recent developments in the study of biofilm structure, and propose combining modern architecture and synthetic microbiology to develop sustainable construction approaches. Recently, Kolodkin‐Gal laboratory and others revealed a role for precipitation of calcium carbonate in the maturation and assembly of bacterial communities with complex structures. Importantly, they demonstrated that different secreted organic materials shape the calcium carbonate crystals formed by the bacterial cells. This provides a proof‐of‐concept for a potential use of bacteria in designing rigid construction materials and altering crystal morphology and function. In this study, we discuss how these recent discoveries may change the current strategies of architecture and construction. We believe that biofilm communities enhanced by synthetic circuits may be used to construct buildings and to sequester carbon dioxide in the process.

Non-target trials with Pseudomonas fluorescens strain CL145A, a lethal control agent of dreissenid mussels (Bivalvia: Dreissenidae)

In an effort to develop an efficacious and environmentally safe method for managing zebra mussels (Dreissena polymorpha) and quagga mussels (Dreissena rostriformis bugensis), we initiated a research project investigating the potential use of bacteria and their natural metabolic products as biocontrol agents. This project resulted in the discovery of an environmental isolate lethal to dreissenid mussels, Pseudomonas fluorescens strain CL145A (Pf-CL145A). In previous published reports we have demonstrated that: 1) Pf-CL145A’s mode of action is intoxication (not infection); 2) natural product within ingested bacterial cells lyse digestive tract epithelial cells leading to dreissenid death; and 3) high dreissenid kill rates (>90%) are achievable following treatment with Pf-CL145A cells, irrespective of whether the bacterial cells are dead or alive. Investigating the environmental safety of Pf-CL145A was also a key element in our research efforts, and herein, we report the results of non-target trials demonstrating Pf-CL145A’s high specificity to dreissenids. These acute toxicity trials were typically single-dose, short-term (24-72 h) exposures to Pf-CL145A cells under aerated conditions at concentrations highly lethal to dreissenids (100 or 200 mg/L). These trials produced no evidence of mortality among the ciliate Colpidium colpoda, the cladoceran Daphnia magna, three fish species (Pimephales promelas, Salmo trutta, and Lepomis macrochirus), and seven bivalve species (Mytilus edulis, Pyganodon grandis, Pyganodon cataracta, Lasmigona compressa, Strophitus undulatus, Lampsilis radiata, and Elliptio complanata). Low mortality (3-27%) was recorded in the amphipod Hyalella azteca, but additional trials suggested that most, if not all, of the mortality could be attributed to some other unidentified factor (e.g., possibly particle load or a water quality issue) rather than Pf-CL145A’s dreissenidkilling natural product. In terms of potential environmental safety, the results of these invertebrate and vertebrate non-target trials are encouraging, but it would be unrealistic to think that dreissenids are the only aquatic organisms sensitive to Pf-CL145A’s dreissenid-killing natural product. Additional testing is needed to better define Pf-CL145A’s margin of safety by identifying the sensitivity of other susceptible organisms. The results of these non-target safety trials – in combination with equally promising mussel control efficacy data – have now led to Pf-CL145A’s commercialization under the product name Zequanox ® , with dead cells as the product’s active ingredient. The commercial availability of only dead-cell Zequanox formulations will eliminate the risk of any possible non-target infection by Pf-CL145A, further reducing environmental concerns. During the non-target project reported herein, the limited quantities of Pf-CL145A cells that we were able to culture severely restricted the number and size of our trials. In contrast, the availability of Zequanox will now greatly expand the opportunities for non-target testing. The trials reported herein – exposing non-target organisms under aerated conditions to unformulated, laboratory-cultured cells – clearly point to Pf-CL145A’s potential for high host specificity, but non-target trials with Zequanox – using PfCL145A cells cultured, killed, and formulated using industrial-scale protocols – will be even more important as they will define the nontarget safety limits of the actual commercial products under a wide range of environmental conditions.

Pseudomonas fluorescens strain CL145A – A biopesticide for the control of zebra and quagga mussels (Bivalvia: Dreissenidae)

Zebra mussels (Dreissena polymorpha) and quagga mussels (Dreissena rostriformis bugensis) are the “poster children” of high-impact aquatic invasive species. In an effort to develop an effective and environmentally acceptable method to control their fouling of raw-water conduits, we have investigated the potential use of bacteria and their natural metabolic products as selective biological control agents. An outcome of this effort was the discovery of Pseudomonas fluorescens strain CL145A – an environmental isolate that kills these dreissenid mussels by intoxication (i.e., not infection). In the present paper, we use molecular methods to reconfirm that CL145A is a strain of the species P. fluorescens, and provide a phylogenetic analysis of the strain in relation to other Pseudomonas spp. We also provide evidence that the natural product lethal to dreissenids is associated with the cell wall of P. fluorescens CL145A, is a heat-labile secondary metabolite, and has degradable toxicity within 24h when applied to water. CL145A appears to be an unusual strain of P. fluorescens since it was the only one among the ten strains tested to cause high mussel mortality. Pipe trials conducted under once-through conditions indicated: (1) P. fluorescens CL145A cells were efficacious against both zebra and quagga mussels, with high mortalities achieved against both species, and (2) as long as the total quantity of bacterial cells applied during the entire treatment period was the same, similar mussel mortality could be achieved in treatments lasting 1.5–12.0h, with longer treatment durations achieving lower mortalities. The efficacy data presented herein, in combination with prior demonstration of its low risk of non-target impact, indicate that P. fluorescens CL145A cells have significant promise as an effective and environmentally safe control agent against these invasive mussels.

Plant-Associated Biofilms

Bacteria colonizing plant surfaces are of great importance in agriculture, having either a negative (pathogens surviving on leaf surfaces) or a positive (beneficial root-colonizing bacteria) role. Plant-associated populations develop in a way that shows similarities to that observed in biofilm formation on abiotic surfaces, and certain genetic determinants are common to both processes. The mechanisms involved in biofilm formation and maintenance on plant surfaces, and their implications for agriculture will be discussed, both in terms of pathogenesis processes and the potential use of bacteria for biocontrol purposes.

Toxicity of gadolinium to some aquatic microbes.

The toxicity of gadolinium to algae and bacteria was determined as part of an effort to develop a biological process to purify drums containing spent nuclear reactor heavy water moderator (D2O). This water was contaminated with high concentrations of gadolinium nitrate, a chemical used as a neutron poison during former nuclear reactor operations at the Savannah River Site (SRS) near Aiken, SC. Nuclear reactors were operated for approximately 30 years at the SRS to produce nuclear weapons materials for national defense. Throughout this period, a heavy water solution of gadolinium nitrate was utilized in a standby emergency shutdown system that could inject this chemical into the reactor moderator coolant water. The chemical was used for this purpose because the high neutron absorption cross sections of some gadolinium isotopes make gadolinium salts such as GdNO3 effective in controlling nuclear activity in aqueous systems (Gilbert et al. 1985; Rodenas et al. 1990). The use of this practice resulted in a large inventory of this degraded heavy water containing gadolinium nitrate. Microbiological and chemical studies were initiated to evaluate the potential use of bacteria and algae for water purification of the drums. Since metals are often toxic to microbes when present at concentrationsmore » substantially higher than natural environmental levels, it was hypothesized that Gd may be toxic to selected microorganisms (algae and bacteria) at the very high concentrations (average 80,000 mg/L, maximum 259,000 mg/L) present in most of the drums. Two principal components of the study included: (1) chemical and microbiological characterization of representative drums, and (2) an evaluation of the toxicity of gadolinium to selected species of algae. In addition to wastewater from nuclear production reactor operations, gadolinium waste is also generated from medical applications, especially MRI, and various electronic components including CD disks. Despite growing and widespread usage of this rare element, there is a paucity of information on the toxicity of gadolinium.« less

Selective incorporation of bacteria by Argopecten purpuratus larvae: implications for the use of probiotics in culturing systems of the Chilean scallop

Experiments on ingestion rates, colonization and impact of inhibitory producer substances bacteria (IPB) on larvae of Argopecten purpuratus, were carried out to evaluate potential use of bacteria as probiotics in cultures of this Chilean scallop. Three selected strains, named as 11, C33 and 77, obtained from larval cultures of A. purpuratus were tested at different concentrations and incubation times. After 6 h of incubation at a concentration of 10 6 cells ml −1, A. purpuratus larvae ingested cells of strains 11 and 77, but not those of C33. When comparing bacterial incorporation among these strains, the 77 became the dominant bacteria of the larval microflora, causing no differences in larval survival at different bacterial concentrations. Our results suggest that strain 77 appears as a potential probiotic for scallop larvae and hence, as a promising method to control and prevent infections in hatcheries systems.