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PubMedDate not supplied

Compartmentalization of metals within the diverse colloidal matrices comprising activated sludge microbial flocs.

Activated sludge floc from a wastewater treatment system was characterized, with regard to principal structural, chemical, and microbiological components and properties, in relation to contaminant-colloid associations and settling. Multiscale analytical microscopies, in conjunction with multimethod sample preparations, were used correlatively to characterize diverse colloidal matrices within microbial floc. Transmission electron microscopy, in conjunction with energy dispersive spectroscopy (EDS), revealed specific associations of contaminant heavy metals with individual bacterial cells and with extracellular polymeric substances (EPS). Floc structure was mapped from the level of gross morphology down to the nano-scale, and flocs were described with respect to settling properties, size, shape, density, porosity, bound water content, and EPS chemical composition; gross surface properties were also measured for correlation with principal floc features. Compartmentalization results based on 171 EDS analyses and representative high-resolution images showed that nano-scale agglomerations of (i) silver (100%) and (ii) zinc (91%) were confined almost entirely to EPS matrices while (iii) Pb (100%) was confined to intracellular granules and (iv) aluminum was partitioned between EPS matrices (41%) and intracellular matrices (59%). The results suggest that engineered changes in microbial physiology and/or in macromolecular EPS composition may influence metal removal efficiencies.

Flocculation↗
PubMed2026

Coarse-grained resource allocation modeling for decoding and rewiring microbial metabolism.

Microbial metabolism is a complex, emergent system driven by the coordinated interplay of intricate and dynamic molecular processes. To elucidate cellular behavior and enable biotechnological applications, quantitative models that address the inherent complexity of metabolism have been developed from a resource allocation perspective. Here, we synthesize recent advances in coarse-grained resource allocation frameworks and their applications in understanding microbial physiology and guiding gene circuit design. These frameworks reveal global regulatory constraints and predict cellular adaptation to nutrient and environmental changes. In addition, they enable the quantification of metabolic costs, the dissection of circuit-host interactions, and the development of strategies for burden mitigation. Collectively, these modeling frameworks provide a powerful platform for uncovering quantitative principles of microbial growth and engineering robust synthetic biological systems.

coarse-grained modeling↗
PubMedDate not supplied

Physical properties of microbial polythioesters: characterization of poly(3-mercaptoalkanoates) synthesized by engineered Escherichia coli.

Physical properties of chiral poly(thioesters), PTEs, prepared by engineered Escherichia coli, were examined by GPC, 13C CP/MAS solid-state NMR, X-ray diffraction, and thermal analysis. Microbial homopolymers of PTEs, poly(3-mercaptopropionate), PMP, and poly(3-mercaptovalerate), PMV, showed different solubility characteristics compared to poly(hydroxyalkanoates), PHAs. Generally, PTEs required higher temperatures for dissolution. Poly(3-mercaptobutyrate), PMB, and PMV dissolve in chloroform, and the molecular weight values were revealed by GPC as 176,000 and 165,000, respectively. The density values for PMP and PMB were 1.42 and 1.27 g/cm3, respectively. These values are similar to those for oxygen analogues. The NMR spectra for PTEs showed that carbonyl carbons are greatly shifted downfield by the sulfur atoms in the chain backbone compared to the PHA family. X-ray powder diffraction data indicated that PTEs are crystalline materials, but they do not crystallize as well as in the PHA family. The melting point, Tm, for PMP was 170 degrees C, which is about 100 degrees C higher than the equivalent oxygen analogue, poly(3-hydroxypropionate), PHP, and almost the same as that of bacterial poly(3-hydroxybutyrate), PHB. According to thermal analysis, only the PMP sample had enhanced heat stability, e.g., the decomposition temperature for PMP was 277 degrees C at 5% weight loss, whereas the values for PHP and PHB were 233 and 260 degrees C at the same weight loss, respectively.

Escherichia coli↗
PubMed2005

Changes in soil microbial community structure associated with two types of genetically engineered plants analyzing by PLFA.

With the rapid expansion of GEPs(genetically engineered plants), people are more and more concerned about the ecological risks brought by their release. Assessing the effect of GEPs on soil microbial ecology is indispensable to study their ecological risks. In our study, the phospholipids fatty acid ( PLFA) method was used to analyze the microbial community of soil samples collected from fields with two types of GEPs-Bt transgenic corn and PVY ( potato virus Y) cell protein gene transgenic potato. The principal components analysis (PCA) showed all controls were on the right of related GEPs samples along the PC1 (the first principal component) axis, which means a decrease of fungi in soils with genetically engineered crop since most of PLFAs that are strongly positively correlated with PC1 represent fungi. For samples collected from Bt transgenic cornfield, the ratios of gram-positive to gram-negative bacteria were less than those of controls. For samples of transgenic potato field, these ratios were lower than those of controls when soils were collected from deep layer (20-40 cm), but were higher when soils collected from surface layer(0-20 cm). For soils collected from 0-20 cm, the ratios of fungi to bacteria for all GEPs samples were at the same level. So were such rations for all controls. Changes of soil microbial community in two types of GEPs fields were detected in our study, but the causes and more information still needs further study.

Bacterial Physiological Phenomena↗
PubMed2005

Microbial isoprenoid production: an example of green chemistry through metabolic engineering.

Saving energy, cost efficiency, producing less waste, improving the biodegradability of products, potential for producing novel and complex molecules with improved properties, and reducing the dependency on fossil fuels as raw materials are the main advantages of using biotechnological processes to produce chemicals. Such processes are often referred to as green chemistry or white biotechnology. Metabolic engineering, which permits the rational design of cell factories using directed genetic modifications, is an indispensable strategy for expanding green chemistry. In this chapter, the benefits of using metabolic engineering approaches for the development of green chemistry are illustrated by the recent advances in microbial production of isoprenoids, a diverse and important group of natural compounds with numerous existing and potential commercial applications. Accumulated knowledge on the metabolic pathways leading to the synthesis of the principal precursors of isoprenoids is reviewed, and recent investigations into isoprenoid production using engineered cell factories are described.

Bioreactors↗
PubMed1997

Developments in metabolic engineering.

The complete sequencing of several microbial genomes has resulted in the increased availability of genes for metabolic engineering. The number of databases and computational tools to deal with this information has also increased. This development has stimulated, and will continue to stimulate, advances in metabolic engineering. Specific recent advances include improvement of pathways for aromatic metabolites, the development of a more complete understanding of the effect of bacterial hemoglobin on cell performance, the development of NMR-based methods for the monitoring of intracellular metabolites and metabolic flux, and the application of metabolic control analysis and metabolic flux analysis to a variety of systems.

Journal Article↗
PubMed2025

The application of AI-driven and engineered intratumoral microbes in cancer therapy.

BACKGROUND: Although investigations of the intratumoral microbiota date back thousands of years, breakthrough transformations have only recently been achieved through high-throughput sequencing and multiomic technologies. These advances have revealed diverse and tumor type-specific microbial communities that drive carcinogenesis via immunomodulation, metabolic reprogramming, and genomic instability. Current cornerstones of cancer therapies-including chemotherapy, radiotherapy, immunotherapy, and targeted therapy-are limited by systemic toxicity, localized tissue damage, drug resistance, and low patient response rates. These constraints underscore the urgent need for more effective and precise therapeutic strategies. MAIN BODY: This review comprehensively integrates artificial intelligence (AI) technologies into the characterization of the intratumoral microbiota, facilitating the development of novel computational pipelines for mapping microbe-host crosstalk. We systematically summarize recent advances in engineered microbial therapeutics, including bacteria designed for targeted antitumor activity and engineered microorganisms that enable the localized delivery of therapeutic agents. Furthermore, this review critically evaluates the safety profiles of microbiota-based interventions and discusses key challenges in clinical translation. CONCLUSIONS: By combining cutting-edge computational technologies, biological research, and clinical insights, this review aims to bridge the gap between microbiome science and oncological practice, pioneering innovative strategies for microbiota-guided diagnostics and personalized cancer therapy.

Humans↗
PubMed2000

Development of biotechnology in India.

India has embarked upon a very ambitious program in biotechnology with a view to harnessing its available human and unlimited biodiversity resources. It has mainly been a government sponsored effort with very little private industry participation in investment. The Department of Biotechnology (DBT) established under the Ministry of Science and Technology in 1986 was the major instrument of action to bring together most talents, material resources, and budgetary provisions. It began sponsoring research in molecular biology, agricultural and medical sciences, plant and animal tissue culture, biofertilizers and biopesticides, environment, human genetics, microbial technology, and bioprocess engineering, etc. The establishment of a number of world class bioscience research institutes and provision of large research grants to some existing universities helped in developing specialized centres of biotechnology. Besides DBT, the Department of Science & Technology (DST), also under the Ministry of S&T, sponsors research at universities working in the basic areas of life sciences. Ministry of Education's most pioneering effort was instrumental in the creation of Biochemical Engineering Research Centre at IIT Delhi with substantial assistance from the Swiss Federal Institute of Technology, Zurich, Switzerland to make available state-of-the-art infrastructure for education, training, and research in biochemical engineering and biotechnology in 1974. This initiative catalysed biotechnology training and research at many institutions a few years later. With a brief introduction, the major thrust areas of biotechnology development in India have been reviewed in this India Paper which include education and training, agricultural biotechnology, biofertilizers and biopesticides, tissue culture for tree and woody species, medicinal and aromatic plants, biodiversity conservation and environment, vaccine development, animal, aquaculture, seri and food biotechnology, microbial technology, industrial biotechnology, biochemical engineering and associated activities such as creation of biotechnology information system and national repositories. Current status of intellectual property rights has also been discussed. Contribution to the India's advances in biotechnology by the industry, excepting a limited few, has been far below expectations. The review concludes with some cautious notes.

Agriculture↗
PubMed1990

Microbial cellulose as a specialty chemical.

Microbial polysaccharides are extensively used commercially as gelling or suspending agents, as protective colloids or as thickening agents. Until recently, microbial cellulose producing systems such as Acetobacter xylinum, had been used largely as model systems for the study of cellulose biosynthesis. Current advances in molecular biology and biochemical engineering promise to usher microbial cellulose into the specialty chemical market. This review will highlight some of the recent progress made in our understanding of microbial cellulose biochemistry and biosynthesis, describe some of its inherent virtues and identify current unique applications of this versatile biopolymer.

Journal Article↗
PubMed2005

[Comparative analysis of in vitro antifungal activity and in vivo acute toxicity of the nystatin analogue S44HP produced via genetic engineering].

New polyene macrolide S44HP was purified from the culture of recombinant Streptomyces noursei strain with engineered nystatin polyketide synthase. S44HP, nystatin (NYS), and amphotericin B (Amph-B) were tested against 19 clinical fungal isolates in agar diffusion assay, which demonstrated clear differences in antifungal activities of these antibiotics. Sodium deoxycholate suspensions of all three antibiotics were subjected to acute toxicity studies in vivo upon intravenous administration in mice. NYS exhibited the lowest acute toxicity in mice in these experiments, while both Amph-B and S44HP were shown to be 4 times more toxic as judged from the LD50 values. While the acute toxicity of S44HP was higher than that of Amph-B, the data analysis revealed a significantly increased LD10 to LD50 dose interval for S44HP compared to Amph-B. The data revealed structural features of polyene macrolides, which might have an impact on both the activity and toxicity profiles of these antibiotics. These results represent the first example of preclinical evaluation of an "engineered" polyene macrolide, and can be valuable for rational design of novel antifungal drugs with improved pharmacological properties.

Amphotericin B↗
PubMed1990

Survival of bacteria during aerosolization.

One form of commercial application of microorganisms, including genetically engineered microorganisms is as an aerosol. To study the effect of aerosol-induced stress on bacterial survival, nonrecombinant spontaneous antibiotic-resistant mutants of four organisms, Enterobacter cloacae, Erwinia herbicola, Klebsiella planticola, and Pseudomonas syringae, were sprayed in separate experiments in a greenhouse. Samples were collected over a distance of 15 m from the spray site for enumeration. Spores of Bacillus subtilis were used as tracers to estimate the effects of dilution on changes in population over distance. Viable counts of P. syringae, Enterobacter cloacae, and K. planticola decreased significantly over a distance of 15 m. Erwinia herbicola showed no significant decline in counts over the same distance. The degree of survival of P. syringae during aerosolization was dependent on ambient environmental conditions (i.e., temperature, relative humidity), droplet size of the aerosol, and prior preparative conditions. Survival was greatest at high relative humidities (70 to 80%) and low temperatures (12 degrees C). Survival was reduced when small droplet sizes were used. The process of washing the cells prior to aerosolization also caused a reduction in their survival. Results from these experiments will be useful in developing sound methodologies to optimize enumeration and for predicting the downwind dispersal of airborne microorganisms, including genetically engineered microorganisms.

Aerosols↗
PubMed2000

Development of applied microbiology to modern biotechnology in Japan.

Development of modern biotechnology in Japan is characterized by unique contributions from applied microbiology and bioindustry. This review tries to summarize these original contributions with special emphasis on industrial production of useful substances by microorganisms. In the first part, development of applied microbiology and bioindustry in the last half of the twentieth century is summarized with a brief overview of the traditional background. In the second part, recent progress is reviewed with citation of typical achievements in biotechnology, applied enzymology, secondary metabolites, genetic engineering, and screening of microbial diversity, respectively.

Amino Acids↗
PubMed1988

Aerial Dispersal and Epiphytic Survival of Pseudomonas syringae during a Pretest for the Release of Genetically Engineered Strains into the Environment.

Prospective experimental field evaluation of genetically engineered microorganisms, such as microbial pest control agents, raises issues of how to properly ascertain their fate and survival in the environment. Field trials with recombinant organisms must reflect requirements for sampling and monitoring. Field trials were conducted at Tulelake, Calif., to monitor the numbers of viable cells of a nonrecombinant strain of Pseudomonas syringae that entered the atmosphere and landed on plants and soil during and after an aerosol spray application. An exponential decrease in numbers of viable cells deposited at increasing distances from three sprayed plots was observed. The relative rate of survival of cells sprayed directly on plants was more than 10 times higher than that of cells dispersed through the air to similar adjacent plants. Results are being used to gain experience with the characteristics of a release site that influence containment or dispersal and to develop appropriate sampling methodologies for evaluating survival and dispersal characteristics of genetically engineered bacteria released into the environment. The ability to make predictions about microbial dispersal and survival will reduce the uncertainties associated with environmental releases of recombinant organisms.

Journal Article↗
PubMed1998

Engineering a recombinant Deinococcus radiodurans for organopollutant degradation in radioactive mixed waste environments.

Thousands of waste sites around the world contain mixtures of toxic chlorinated solvents, hydrocarbon solvents, and radionuclides. Because of the inherent danger and expense of cleaning up such wastes by physicochemical methods, other methods are being pursued for cleanup of those sites. One alternative is to engineer radiation-resistant microbes that degrade or transform such wastes to less hazardous mixtures. We describe the construction and characterization of recombinant Deinococcus radiodurans, the most radiation-resistant organism known, expressing toluene dioxygenase (TDO). Cloning of the tod genes (which encode the multicomponent TDO) into the chromosome of this bacterium imparted to the strain the ability to oxidize toluene, chlorobenzene, 3,4-dichloro-1-butene, and indole. The recombinant strain was capable of growth and functional synthesis of TDO in the highly irradiating environment (60 Gy/h) of a 137Cs irradiator, where 5x10(8)cells/ml degraded 125 nmol/ml of chlorobenzene in 150 min. D. radiodurans strains were also tolerant to the solvent effects of toluene and trichloroethylene at levels exceeding those of many radioactive waste sites. These data support the prospective use of engineered D. radiodurans for bioremediation of mixed wastes containing both radionuclides and organic solvents.

Chromosome Mapping↗
PubMed1996

Engineered biosynthesis of peptide antibiotics.

In certain bacteria and filamentous fungi, a wide variety of bioactive peptides are produced non-ribosomally on large protein templates, called peptide synthetases. Recently, significant progress has been made towards understanding the modular arrangement of these complex multifunctional enzymes and the mechanisms by which they generate their corresponding peptide products. It has now been established that the synthesis of bioactive peptides and the specification of their sequence are brought about by a protein template that contains the appropriate number and the correct order of activating units (domains). These advances have enabled the development of a technique that permits the construction of hybrid genes encoding peptide synthetases with specifically altered substrate specificities. A programmed alteration within the primary structure of a peptide antibiotic is achieved by the substitution of an amino acid-activating domain in the corresponding protein template at the genetic level by a two-step recombination method. It utilizes successive gene disruption and reconstitution and demonstrates, for the first time, the potential of genetic engineering in the biosynthesis of novel peptide antibiotics. Many organisms, for instance those that cause diseases like tuberculosis and pneumonia, have evolved potent mechanisms of drug resistance. Therefore, the targeted engineering of peptide antibiotics could be one potential strategy for the development of novel drugs that overcome this resistance.

Amino Acid Sequence↗
PubMed2000

Bifidobacterium longum as a delivery system for cancer gene therapy: selective localization and growth in hypoxic tumors.

A fundamental obstacle in gene therapy for cancer is the specific delivery of an anticancer gene product to a solid tumor, and yet no systemic delivery system that specifically targets solid tumors currently exists. A strain of domestic bacteria, Bifidobacterium longum, which is nonpathogenic and anaerobic, selectively localized and proliferated in several types of mouse solid tumors after systemic application. In this report, we further describe a novel approach to cancer gene therapy in which genetically engineered Bifidobacterium is used as a tumor-specific vector. Similarly to wild-type B. longum, genetically engineered B. longum could be detected in tumor tissue only and was not found in a large survey of normal mouse tissues after intravenous injection. This finding strongly suggests that obligate anaerobic bacteria such as Bifidobacterium can be used as highly specific gene delivery vectors for cancer gene therapy.

Animals↗
PubMed2001

Molecular genetics and industrial microbiology--30 years of marriage.

Thirty years ago, molecular genetics and industrial microbiology joined their hands in marriage. The event took place in Prague at the first Symposium on the Genetics of Industrial Microorganisms. My closing plenary lecture, titled "The Marriage of Genetics and Industrial Microbiology--After a long Engagement, a Bright Future," dealt with industrial uses of mutants, the lack of success with genetic recombination, control of branched and unbranched pathways and thoughts about the future, e.g., identifying the biochemical sites of beneficial mutations, exploitation of recombination and genetic means to increase production of enzymes. It is quite amazing that the Symposium was held 3 years before the advent of recombinant DNA technology. This important meeting was followed in 1976 by the first Genetics and Molecular Biology of Industrial Microorganisms (GMBIM) meeting in Orlando, all of the six subsequent GMBIM meetings being held in Bloomington, Indiana. Today, thousands of biotechnology companies are in existence making great progress in the pharmaceutical and agricultural sectors. Hundreds of new genetically engineered compounds, produced in microbial, mammalian or insect cells, are in clinical trails and many are already being marketed. The field is booming with new technologies such as transgenic animals and plants, site-directed mutagenesis, combinatorial biosynthesis, gene therapy, antisense, abzymes, high-throughput screening, monoclonal antibodies, PCR and many more. Agricultural biotechnology has made great strides but unfortunately its progress is being delayed by political controversy.

Agriculture↗