Bacteria Dwelling Research Articles

Potential Nitrogen Fixing Rhizobia Isolated from Some Wild Legumes of Nagaland Based on RAPD with Nif-directed Primer and Their Biochemical Activities

Wild legumes are widely dispersed and can survive in challenging environments as bacteria dwell in their nodules and help each other. Although Nagaland is home to many wild legume varieties, research on the microbial diversity that goes along with them is still in its infancy. This work aimed to characterize several wild legume root nodules and distinguish possible rhizobial isolates using RAPD and nif-directed RPO1 primer. Nodule bacteria were isolated in Yeast extract culture media. Based on their colony morphology, 150 isolates were selected for performing RAPD with nif-directed RPO1 primer. Eighty-four isolates were bonded with RPO1 primer, and a few biochemical tests were conducted on RPO1-positive isolates. Activities that promoted plant development were also investigated for these isolates. Of all the isolates, 18 exhibited phosphate solubilization capacity, while 38 isolates were found to produce IAA. This study entails a large variety of rhizobia in the nodules, which were able to promote growth. Hence, these isolates promise to be bio-fertilizers that could improve agricultural operations.

The Rare Actinobacterium Crossiella sp. Is a Potential Source of New Bioactive Compounds with Activity against Bacteria and Fungi.

Antimicrobial resistance has become a global problem in recent decades. A gradual reduction in drug discoveries has led to the current antimicrobial resistance crisis. Caves and other subsurface environments are underexplored thus far, and they represent indispensable ecological niches that could offer new molecules of interest to medicine and biotechnology. We explored Spanish show caves to test the bioactivity of the bacteria dwelling in the walls and ceilings, as well as airborne bacteria. We reported the isolation of two strains of the genus Crossiella, likely representing a new species, isolated from Altamira Cave, Spain. In vitro and in silico analyses showed the inhibition of pathogenic Gram-positive and Gram-negative bacteria, and fungi, as well as the taxonomical distance of both strains from their closest relative, Crossiella cryophila. The presence of an exclusive combination of gene clusters involved in the synthesis of lanthipeptides, lasso peptides, nonribosomal peptides and polyketides indicates that species of this genus could represent a source of new compounds. Overall, there is promising evidence for antimicrobial discovery in subterranean environments, which increases the possibility of identifying new bioactive molecules.

Three Novel Bacteriophages, J5a, F16Ba, and z1a, Specific for Bacillus anthracis, Define a New Clade of Historical Wbeta Phage Relatives.

Bacillus anthracis is a potent biowarfare agent, able to be highly lethal. The bacteria dwell in the soil of certain regions, as natural flora. Bacteriophages or their lytic enzymes, endolysins, may be an alternative for antibiotics and other antibacterials to fight this pathogen in infections and to minimize environmental contamination with anthrax endospores. Upon screening environmental samples from various regions in Poland, we isolated three new siphophages, J5a, F16Ba, and z1a, specific for B. anthracis. They represent new species related to historical anthrax phages Gamma, Cherry, and Fah, and to phage Wbeta of Wbetavirus genus. We show that the new phages and their closest relatives, phages Tavor_SA, Negev_SA, and Carmel_SA, form a separate clade of the Wbetavirus genus, designated as J5a clade. The most distinctive feature of J5a clade phages is their cell lysis module. While in the historical phages it encodes a canonical endolysin and a class III holin, in J5a clade phages it encodes an endolysin with a signal peptide and two putative holins. We present the basic characteristic of the isolated phages. Their comparative genomic analysis indicates that they encode two receptor-binding proteins, of which one may bind a sugar moiety of B. anthracis cell surface.

Isolation and characterization of fast-growing green snow bacteria from coastal East Antarctica.

Snow microorganisms play a significant role in climate change and affecting the snow melting rate in the Arctic and Antarctic regions. While research on algae inhabiting green and red snow has been performed extensively, bacteria dwelling in this biotope have been studied to a much lesser extent. In this study, we performed 16S rRNA gene amplicon sequencing of two green snow samples collected from the coastal area of the eastern part of Antarctica and conducted genotypic and phenotypic profiling of 45 fast‐growing bacteria isolated from these samples. 16S rRNA gene amplicon sequencing of two green snow samples showed that bacteria inhabiting these samples are mostly represented by families Burkholderiaceae (46.31%), Flavobacteriaceae (22.98%), and Pseudomonadaceae (17.66%). Identification of 45 fast‐growing bacteria isolated from green snow was performed using 16S rRNA gene sequencing. We demonstrated that they belong to the phyla Actinobacteria and Proteobacteria, and are represented by the genera Arthrobacter, Cryobacterium, Leifsonia, Salinibacterium, Paeniglutamicibacter, Rhodococcus, Polaromonas, Pseudomonas, and Psychrobacter. Nearly all bacterial isolates exhibited various growth temperatures from 4°C to 25°C, and some isolates were characterized by a high level of enzymatic activity. Phenotyping using Fourier transform infrared (FTIR) spectroscopy revealed a possible accumulation of intracellular polymer polyhydroxyalkanoates (PHA) or lipids in some isolates. The bacteria showed different lipids/PHA and protein profiles. It was shown that lipid/PHA and protein spectral regions are the most discriminative for differentiating the isolates.

Modeling the Potential of Submarine Groundwater Discharge to Facilitate Growth of Vibrio cholerae Bacteria

Submarine groundwater discharge (SGD), the discharge of terrestrial groundwater to the ocean, can govern the coastal benthic environment. Bacteria such as Vibrio cholerae inhabit coastal waters and sediments, whose growth can be influenced by SGD. In particular, salinity changes introduced by SGD could have a positive effect on the abundance but also virulence of non-halophilic V. cholera bacteria dwelling in coastal waters and shallow marine sediments. Here we assess potential effects of SGD on the environmental properties that favor V. cholerae in a numerical modeling study representing multiple scenarios. Approaching natural systems, simulation results reveal a high sensitivity of non-halophilic Vibrio cholerae growth to SGD and its primary driving factors. This dependency leads to highest growth potential at high groundwater inflow and low hydraulic conductivity of the aquifer as well as for steep sea-side boundary slopes. Besides its minor impact on the extent of SGD in our model, dispersion is a crucial limiting factor for V. cholerae habitat. We conclude that there is a close connection between the driving factors of SGD and low salinity zones along a coastal slope, and recommend taking these into consideration for evaluating local V. cholerae outbreaks.

Indocyanine Green Loaded PLGA Film Coated Coronary Stents for Photo-Triggered in situ Biofilm Eradication

Biofilm formation is a major impeding factor for successful angioplasty. Bacteria dwelling in the biofilm are resistant to most systemically administered antibodies necessitating stent removal which is often not a suitable option for patients suffering from coronary artery disease. In the quest to develop a suitable system for combating biofilm development on stents, we have formulated a stable titanium surface modification based on electrostatic interactions and investigated in situ. For this purpose, surface activated titanium was modified with amine rich (3-Aminopropyl)-triethoxysilane (APTES) to enable coating with a photosensitising drug containing polymer (Indocyanine green (ICG)/ poly(lactic-co-glycolic acid) [PLGA]) solution. The surface modifications were characterised using scanning electron microscopy and confocal microscopy together with antibacterial studies were used to qualitatively and quantitatively determine the antibacterial effect respectively. IR (810 nm) laser was used to trigger ICG leading to a dramatic reduction (99.96%) in bacterial viability inside the biofilm. The polymer, PLGA used in this study is a widely explored biocompatible and biodegradable polymer thereby making it an excellent choice for coating materials intended for use in biological systems. Indocyanine green on the other hand is a well-documented diagnostic agent and has gained much popularity in the recent past as a photosensitising agent for use in photodynamic therapy. Using this novel technique the photosensitising ICG could be triggered using IR laser leading to the generation of bacteriostatic reactive oxygen species at the site of irradiation. Due to the inertness of the photosensitising ICG in the absence of IR trigger, risk of antibacterial resistance could be ruled out. In the absence of biofilm formation following stent insertion/angioplasty, the ICG containing PLGA degrades with time. This first of its kind minimally invasive method would help avoid/treat bacterial infections and biofilm formation on coronary stents.

Approaches based on passive and active antibacterial coating on titanium to achieve antibacterial activity.

Titanium (Ti) and its alloys are widely applied as orthopedic implants for hip and knee prosthesis, fixation, and dental implants. However, Ti and its alloys are bioinert and susceptible to bacteria and biofilm formation. Strategies for improving the antibacterial properties of Ti can be divided into two approaches, namely, passive coating and active coating on the Ti surface. Passive coating on Ti mainly kills the bacteria in contact but does not kill plankton or bacteria dwell in the bone tissue around the Ti implant. Active coating mainly involves the release of antibacterial agents to kill the bacteria, but this may result in the development of bacterial resistance. Both strategies include advantages and disadvantages. This article reviews the current and potential future approaches for improving antibacterial activity on Ti. We mainly focus on current approaches for fabricating antibacterial Ti and its limitations and countermeasures, and provide direction for further studies of biofunctionalization of Ti with antibacterial properties. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 106A:2531-2539, 2018.

An Ounce of Prevention Saves Tons of Lives: Infection in Burns.

Modern day burn care continues to wage an uphill battle against an enemy that evolves faster than we can develop weapons. Bacteria (bioburden) are everywhere and can infiltrate anywhere within our susceptible population of burn patients. This is why prevention of infection is key to improving their survival and outcome. To reduce the incidence of infection in the burn patient population. Review of pertinent recent literature regarding infection prevention and control in the intensive care unit setting. We propose that bioburden is one of the central elements in the infectious cycle that is ever-present in burn units. The mechanism of bacterial entry into the unit and subsequent transmission and infection are delineated. Recommendations for mitigating this risk are provided to guide future clinicians in their care of burn patients. The treatment of infection and sepsis against highly adaptable bacteria is often insurmountable by ill patients. In this process, bioburden needs to be corralled to have any success. Thus, preventing organisms from entering the unit and transferring onto other patients, and eliminating the bacteria dwelling in the unit are all necessary actions in this battle. Ultimately, maintaining a culture that is constantly wary of this risk only can achieve this goal.

Bacterial biomineralization: new insights from Myxococcus -induced mineral precipitation

Abstract Bacteria have contributed to the formation of minerals since the advent of life on Earth. Bacterial biomineralization plays a critical role on biogeochemical cycles and has important technological and environmental applications. Despite the numerous efforts to better understand how bacteria induce/mediate or control mineralization, our current knowledge is far from complete. Considering that the number of recent publications on bacterial biomineralization has been overwhelming, here we attempt to show the importance of bacteria–mineral interactions by focusing in a single bacterial genus, Myxococcus , which displays an unusual capacity of producing minerals of varying compositions and morphologies. First, an overview of the recent history of bacterial mineralization, the most common bacteriogenic minerals and current models on bacterial biomineralization is presented. Afterwards a description of myxobacteria is presented, followed by a section where Myxococcus -induced precipitation of a number of phosphates, carbonates, sulphates, chlorides, oxalates and silicates is described and discussed in lieu of the information presented in the first part. As concluding remarks, implications of bacterial mineralization and perspectives for future research are outlined. This review strives to show that the mechanisms which control bacterial biomineralization are not mineral- or bacterial-specific. On the contrary, they appear to be universal and depend on the environment in which bacteria dwell.

Bacteriology of Callus of Closed Fractures of Tibia and Femur

More than 1% of closed fractures of lower limbs and 6% of orthopedic implants are complicated by inflammation caused by infection despite of all precautionary methods taken. The question arises whether this clinical complication is not caused by bacteria dwelling in limb tissues. Skin, subcutaneous fat, muscle, and fracture gap callus were obtained from 71 adult patients operated on due to closed fractures of tibia or femur; 28 because of comminuted fractures and mal-alignment of bone axis with nonoperative means, and 43 due to delayed healing and unstable union. Aerobic bacteria were isolated from gap callus of 14% healing and 35% nonhealing fractures. No isolates were found in subcutis and only in 3% in muscles. No anaerobic bacteria were detected. Polymerase chain reaction amplifications of 16S rRNA were found positive in 42% of callus specimens proving presence of bacterial DNA even when no isolates were found. The 95% similarity of the genetic pattern of some strains from foot skin and callus, estimated with random amplification of polymorphic DNA technique, suggested their foot skin origin. The colonizing bacterial cells and their DNA were detected in fracture callus but not in other deep tissues. Contamination was precluded by lack of isolates in disinfected cutis, subcutis, muscles, and materials used for sampling cultured after surgery. We suggest that certain strains of bacteria dwell in normal tissues of lower limbs and may cause inflammation upon stimulation by trauma. Their source may be tissue fluid, superficial and deep lymphatics, and lymph serving the physiologic transport to the regional lymph nodes of microorganisms penetrating foot skin during microinjuries.

Six factors that increase the activity of antibiotics in vivo

The traditional study of antibiotic activity in vitro obviously cannot incorporate all host factors that may increase or decrease the activity, which may be bacteriostatic and/or bactericidal. Some specific host factors which canincrease the activity of antibiotics, thus producing host-antibiotic synergy, are: 1) biotransformation of the administered antibiotic to a more active molecule, 2) pH of the infected focus, 3) elevated temperature of the host, 4) effect of heat labile serum factors on bacteria exposed to antibiotics, 5) effect of local tissue factors on antibacterial activity, and 6) effect of phagocytic cell son bacteria exposed to antibiotics. A seventh host factor, which increases the practical antibiotic effect, but not its actual activity, is concentrating mechanisms which are most conspicuous in the kidney and the liver. Conversely, host factors which maydecrease the activity of antibiotics in vivo are: 1) biotransformation (metabolism) of the antibiotic to less active forms, 2) pH of the infected focus, 3) binding to albumin or other serum or tissue components, 4) antagonism by local tissue components other than pH (e. g., bile, cations, osmolarity), 5) anaerobic conditions (low Eh), 6) nutritional factors on bacterial metabolism, 7) foreign body effect, and 8) barriers to drug entry into precise locus where bacteria dwell (e. g. abscess cavity, cerebrospinal fluid, intracellular location). These barriers do not change the actual activity of antibiotics — only their practical effects, by excluding them and thus lowering their concentrations. The same is true of a ninth factor, physiological mechanisms which remove antibiotic from systemic compartments, as in secretion of antibiotic by liver and kidney.