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PubMed2006

Low sensitivity of histology to predict the presence of microorganisms in suspected aseptic loosening of a joint prosthesis.

Intraoperative histology has a high specificity and sensitivity when a septic prosthesis loosening is suspected. However, its usefulness to predict the presence of microorganisms when aseptic loosening is suspected is not well defined. Intraoperative histology and cultures from periprosthetic tissue of 61 revision arthroplasties performed owing to suspected aseptic loosening were retrospectively reviewed. Frozen sections were evaluated following Mirra's criteria (adapted by Feldman). Culture was considered positive when the same microorganism was isolated in at least two samples. The cultures were positive in 12 cases and coagulase-negative staphylococci were the most common microorganisms (11 cases). In six out of 12 cases (50%), the histology revealed more than five polymorphonuclear leukocytes per high-power field. The sensitivity, specificity, positive and negative predictive value of histology to detect the presence of microorganisms was 50, 81, 40 and 86%, respectively. In conclusion, intraoperative histology using Mirra's criteria had a low sensitivity to predict the presence of microorganisms in samples from suspected aseptic prosthetic loosening.

Aged↗
PubMed2006

Social evolution theory for microorganisms.

Microorganisms communicate and cooperate to perform a wide range of multicellular behaviours, such as dispersal, nutrient acquisition, biofilm formation and quorum sensing. Microbiologists are rapidly gaining a greater understanding of the molecular mechanisms involved in these behaviours, and the underlying genetic regulation. Such behaviours are also interesting from the perspective of social evolution - why do microorganisms engage in these behaviours given that cooperative individuals can be exploited by selfish cheaters, who gain the benefit of cooperation without paying their share of the cost? There is great potential for interdisciplinary research in this fledgling field of sociomicrobiology, but a limiting factor is the lack of effective communication of social evolution theory to microbiologists. Here, we provide a conceptual overview of the different mechanisms through which cooperative behaviours can be stabilized, emphasizing the aspects most relevant to microorganisms, the novel problems that microorganisms pose and the new insights that can be gained from applying evolutionary theory to microorganisms.

Bacterial Physiological Phenomena↗
PubMed2004

Multicellular microorganisms: laboratory versus nature.

Our present in-depth knowledge of the physiology and regulatory mechanisms of microorganisms has arisen from our ability to remove them from their natural, complex ecosystems into pure liquid cultures. These cultures are grown under optimized laboratory conditions and allow us to study microorganisms as individuals. However, microorganisms naturally grow in conditions that are far from optimal, which causes them to become organized into multicellular communities that are better protected against the harmful environment. Moreover, this multicellular existence allows individual cells to differentiate and acquire specific properties, such as forming resistant spores, which benefit the whole population. The relocation of natural microorganisms to the laboratory can result in their adaptation to these favourable conditions, which is accompanied by complex changes that include the repression of some protective mechanisms that are essential in nature. Laboratory microorganisms that have been cultured for long periods under optimized conditions might therefore differ markedly from those that exist in natural ecosystems.

Animals↗
PubMed2003

IgG antibodies against microorganisms and atopic disease in Danish adults: the Copenhagen Allergy Study.

BACKGROUND: Seropositivity to food-borne and orofecal microorganisms (hepatitis A virus, Helicobacter pylori, and Toxoplasma gondii ), which are considered to be markers of poor hygiene, has been reported to be associated with a lower prevalence of atopy. In contrast, colonization of the gut with Clostridium difficile, a potential intestinal bacterial pathogen, in early childhood may be associated with a higher prevalence of atopy. OBJECTIVE: The objective of this study was to investigate the association between atopy and exposure to 2 groups of food-borne and orofecal microorganisms: (1) markers of a poor hygiene and (2) intestinal bacterial pathogens. METHODS: A cross-sectional population-based study of 15- to 69-year-olds living in Copenhagen, Denmark, was carried out in 1990 to 1991. Atopy was defined as a positive test result for specific IgE to at least 1 of 6 inhalant allergens. Exposure to microorganisms was assessed as IgG seropositivity to microorganisms. RESULTS: Seropositivity to 2 or 3 markers of poor hygiene (hepatitis A virus, H pylori, and T gondii ) was associated with a lower prevalence of atopy (adjusted odds ratio, 0.5; 95% CI, 0.3 to 0.8). In contrast, seropositivity to 2 or 3 intestinal bacterial pathogens (C difficile, Campylobacter jejuni, and Yersinia enterocolitica ) was associated with a higher prevalence of atopy (adjusted odds ratio, 1.7; 95% CI, 1.2 to 2.6). CONCLUSION: Exposure to markers of poor hygiene was associated with a lower prevalence of atopy, whereas exposure to intestinal bacterial pathogens was associated with a higher prevalence of atopy. These findings raise the hypothesis that different groups of food-borne and orofecal microorganisms may have different effects on the risk of atopy.

Adolescent↗
PubMed2001

Microorganisms asssociated with Withania somnifera leaves.

Microorganisms including bacteria, actinomycetes and fungi were recovered from the leaves of Withania somnifera, which were collected from two altitudinal ranges (0-300 m and 1700-2000 m) in the Asir region, Saudi Arabia. Types and numbers of microorganisms varied according to the altitude and the month of collection. The number of microorganisms was higher on old leaves than that on young ones in most cases. Low altitude exhibited more microorganisms than high altitude. The relationship between meteorological factors and type and number of the recovered microorganisms is discussed. Inoculation of detached healthy leaves of Withania by all recovered fungal species revealed only Alternaria solani as a pathogen of this plant. To confirm pathogenicity, scanning and transmission electron microscopic examination revealed the colonization of this pathogen inside the leaf tissue. Penetration of Withania leaves by the fungus occurred only through stomata, and the invading hyphae were located in the intercellular spaces of leaf tissues. Ultrastructural changes noted in infected cells included changes in chloroplasts and the invagination of the host plasma membrane.

Actinomycetales↗
PubMed2000

Antimicrobial activity of synthetic salivary peptides against voice prosthetic microorganisms.

OBJECTIVES: To investigate whether synthetic salivary antimicrobial peptides have an inhibitory effect on the growth of bacteria and yeasts isolated from used silicone rubber voice prostheses. METHODS: The antimicrobial activities of six synthetic salivary peptides (histatin 5, dhvarl, dhvar4, dhvar5, lactoferrin b 1730 [LFb 17-30], and cystatin S1-15) at concentrations of 2 and 4 mg/mL were determined against different oropharyngeal yeast (four) and bacterial (eight) strains and against a "total microflora" isolated from explanted voice prostheses using agar diffusion tests. The spectrum of susceptible microorganisms was determined qualitatively. RESULTS: Histatin 5 and cystatin S1-15 did not show any antimicrobial activity against the microorganisms involved in this study. Dhvar1 was active against some of the oropharyngeal microorganisms tested, including the yeast strains, but not against Rothia dentocariosa, Staphylococcus aureus, Escherichia coli, and the total microflora Dhvar4 was active against all microorganisms tested, including the total microflora. Dhvar5 lacked activity against E coli and the total microflora LFb 1730 did not inhibit the growth of any of the yeast strains involved and showed only minor activity against some of the bacterial strains. LFb 1730 slightly inhibited the growth of the total microflora from an explanted prosthesis. CONCLUSIONS: The synthetic salivary peptide dhvar4 has a broad antimicrobial activity against all microorganisms that are commonly isolated from explanted voice prostheses, including yeasts. Therewith, it may represent a useful drug, as an alternative for antibiotics and antimycotics employed in various ways to prolong the lifetime of voice prostheses in laryngectomees.

Bacteria↗
PubMed2002

Increased microorganisms DNA levels in peripheral blood monocytes from psoriatic patients using PCR with universal ribosomal RNA primers.

It has long been suspected that systemic and focal infections cause or exacerbate psoriatic lesions. We previously showed that peripheral blood monocytes in psoriatic patients are activated and overproduce inflammatory cytokines. In addition, it has been reported that macrophages activated by ingesting microorganisms release tumor necrosis factor (TNF)-alpha and interleukin (IL)-1beta. Therefore we hypothesized that the monocytes in psoriatic patients may be activated by ingesting microorganisms and overproduce inflammatory cytokines. We examined the detection of microorganism DNA in monocytes from 15 patients with psoriasis vulgaris and from 12 healthy controls. DNA was extracted from monocytes, and a polymerase chain reaction (PCR) assay was performed for the detection using universal primers from conserved regions of the bacterial 16S ribosomal RNA gene or the fungal 18S rRNA gene. At the same time, we calculated the psoriasis area and severity index (PASI) scores and analyzed their correlations with the microorganisms DNA levels. The results showed that bacterial 16S DNA levels in monocytes were significantly higher in psoriatic patients than in controls. The fungal 18S DNA levels were also higher in psoriatic patients than in controls, but the differences were not significant. Although the microorganisms DNA levels in monocytes of psoriatic patients were high, there was no correlation between the bacterial DNA levels in monocytes of the psoriatics and PASI scores. Our study suggests that monocytes in psoriatic patients engulf more bacteria than there in controls, causing an activation of monocytes and triggering the formation of new lesions in the initial stages of psoriasis.

Adult↗
PubMed1989

Effect of critical surface tension on retention of oral microorganisms.

The effect of critical surface tension on the initial retention of microorganisms from unstimulated human saliva was tested in a flow cell system. Prior to each experiment the total numbers and the morphotypes of microorganisms present in saliva were recorded. The test surfaces were prepared to display known increasing critical surface tensions, as verified and standardized by contact angle measurements. Surfaces of initially low (20-22 mN/m), medium (35-38 mN/m) and high (greater than 50 mN/m) critical surface tension were exposed to saliva at a flow rate of 1 ml/min. Microbiota and biofilm material associated with the test surface after 15 min of salivary exposure, were then subjected to standard detachment forces, by introducing a cell-free rinsing fluid at two different shear rates. Both the attachment and the detachment phases were executed at room temperature or 37 degrees C. The retained population was counted in three different zones of the test surfaces with a light microscope and statistically tested for correlation to the main variables (critical surface tension, flow rate and temperature) and interactions. Retention success was significantly dependent on the initial critical surface tension and the flow rate. Surfaces of medium critical surface tension, representative of human tooth surfaces and most restorative dental materials, retained the highest numbers of microorganisms in comparison with the other surfaces tested, with no statistically verified selectivity in proportions of retained coccoid and rodshaped microorganisms for any surface. A 30-fold increase of the flow rate resulted in a 70-80% reduction of the retention success, with a higher relative number of cocci present on all the test surfaces. These results demonstrate that initial retention of microorganisms to surfaces is non-specific with regard to morphotypes, but is strongly related both to the mechanical removal forces and the surface energetic state of the solid surface exposed. Retention of microbial populations at interfaces might, therefore, be controllable by advance selection of the critical surface tensions and predicted if shear forces at given sites are known.

Bacterial Adhesion↗
PubMed2002

Antimicrobial activity of garlic, tea tree oil, and chlorhexidine against oral microorganisms.

OBJECTIVE: To compare the antimicrobial activity of tea tree oil, garlic, and chlorhexidine solutions against oral microorganisms. METHOD: The five-week study consisted of thirty subjects. The first week was considered baseline. All subjects used a control solution (second week), and were randomly divided into the three groups (third week): G1-0.12% chlorhexidine; G2 - 2.5% garlic (Allium sativum, L.); and G3 - 0.2% tea tree oil (Melaleuca alternifolia). Dishes containing blood agar and Mitis Salivarius Bacitracin agar (MSB) were inoculated with the subjects' saliva (collected twice a week). Total microorganisms and mutans streptococci were counted in blood agar and MSB, respectively. RESULTS: Chlorhexidine and garlic groups showed antimicrobial activity against mutans streptococci, but not against other oral microorganisms. The tea tree oil group showed antimicrobial activity against mutans streptococci and other oral microorganisms. Maintenance of reduced levels of microorganisms was observed only for garlic and tea tree oil during the two consecutive weeks (fourth and fifth). Unpleasant taste (chlorhexidine 40%, tea tree oil 30%, garlic 100%), burning sensation (chlorhexidine 40%, tea tree oil 60%, garlic 100%), bad breath (chlorhexidine 40%, tea tree oil 20%, garlic 90%), and nausea (chlorhexidine 0%, tea tree oil 10%, garlic 30%) were reported. CONCLUSION: Garlic and tea tree oil might be an alternative to chlorhexidine.

Adolescent↗
PubMed2004

[The effects of fluorescent lamp coated with a photocatalyst film on the number of floating microorganisms or smell molecules in a room installed with the lamp].

Fluorescent lamp that is coated with a photocatalyst film, titanium dioxide (TiO2), can catalyze the microorganisms and smell producing molecules that touch the membrane. In this report, we examined the effect of this coated lamp by the number of floating microorganisms or smell molecules in a room installed with this lamp. The number of floating microorganisms was examined independently in different laboratories before and after installing the lamps in an animal facility and a vegetable processing room of a food company. We found that the number of floating microorganisms was significantly reduced after the installation of this coated lamp. To test for smell molecules, acetaldehyde was injected into a closed chamber installed with the coated lamp and the result was compared to a control where a regular fluorescent lamp was used. The acetaldehyde concentration did not change with the regular lamp but was halved after 1h with the photocatalyst coated lamp. To test the effect in real settings, questionnaires were filled out by restroom users in several different places. About 90% of those surveyed answered that there was a reduction of smell after the installation of the photocatalyst coated lamp. We concluded that the installation of this coated fluorescent lamp reduced not only the floating microorganisms but the smell in various practical situations.

Air Microbiology↗
PubMed1989

Novel method for monitoring genetically engineered microorganisms in the environment.

A method has been devised for directly detecting and monitoring genetically engineered microorganisms (GEMs) by using in vitro amplification of the target DNAs by a polymerase chain reaction and then hybridizing the DNAs with a specific oligonucleotide or DNA probe. A cloned 0.3-kilobase napier grass (Pennisetum purpureum) genomic DNA that did not hybridize to DNAs isolated from various microorganisms, soil sediments, and aquatic environments was inserted into a derivative of a 2,4-dichlorophenoxyacetic acid-degradative plasmid, pRC10, and transferred into Escherichia coli. This genetically altered microorganism, seeded into filter-sterilized lake and sewage water samples (10(4)/ml), was detected by a plate count method in decreasing numbers for 6 and 10 days of sample incubation, respectively. The new method detected the amplified unique marker (0.3-kilobase DNA) of the GEM even after 10 to 14 days of incubation. This method is highly sensitive (it requires only picogram amounts of DNA) and has an advantage over the plate count technique, which can detect only culturable microorganisms. The method may be useful for monitoring GEMs in complex environments, where discrimination between GEMs and indigenous microorganisms is either difficult or requires time-consuming tests.

Colony Count, Microbial↗
PubMed1992

Reductive debromination of the commercial polybrominated biphenyl mixture firemaster BP6 by anaerobic microorganisms from sediments.

Anaerobic microorganisms eluted from three sediments, one contaminated with polybrominated biphenyls (PBBs) and two contaminated with polychlorinated biphenyls, were compared for their ability to debrominate the commercial PBB mixture Firemaster. These microorganisms were incubated with reduced anaerobic mineral medium and noncontaminated sediment amended with Firemaster. Firemaster averages six bromines per biphenyl molecule; four of the bromines are substituted in the meta or para position. The inocula from all three sources were able to debrominate the meta and para positions. Microorganisms from the Pine River (St. Louis, Mich.) contaminated with Firemaster, the Hudson River (Hudson Falls, N.Y.) contaminated with Aroclor 1242, and Silver Lake (Pittsfield, Mass.) contaminated with Aroclor 1260 removed 32, 12, and 3% of the meta plus para bromines, respectively, after 32 weeks of incubation. This suggests that previous environmental exposure to PBBs enhances the debromination capability of the sediment microbial community through selection for different strains of microorganisms. The Pine River inoculum removed an average of 1.25 bromines per biphenyl molecule during a 32-week incubation period, resulting in a mixture potentially more accessible to aerobic degradation processes. No ortho bromine removal was observed. However, when Firemaster was incubated with Hudson River microorganisms that had been repeatedly transferred on a pyruvate medium amended with Aroclor 1242, 17% of the meta and para bromines were removed after 16 weeks of incubation and additional debromination products, including 2-bromobiphenyl and biphenyl, were detected. This suggests the possibility for ortho debromination, since all components of the Firemaster mixture have at least one ortho-substituted bromine.(ABSTRACT TRUNCATED AT 250 WORDS)

Aroclors↗
PubMed1995

Microorganism gram-type differentiation based on pyrolysis-mass spectrometry of bacterial Fatty Acid methyl ester extracts.

Curie-point pyrolysis (Py)-mass spectrometry has been used to differentiate 19 microorganisms by Gram type on the basis of the methyl esters of their fatty acid distribution. The mass spectra of gram-negative microorganisms were characterized by the presence of palmitoleic acid (C(inf16:1)) and oleic acid (C(inf18:1)), as well as a higher abundance of palmitic acid (C(inf16:0)) than pentadecanoic acid (C(inf15:0)). For gram-positive microorganisms, a signal of branched C(inf15:0) (isoC(inf15:0) and/or anteisoC(inf15:0)) more intense than that of palmitic acid was observed in the mass spectra. Principal components analysis of these mass spectral data segregated the microorganisms investigated in this study into three discrete clusters that correlated to their gram reactions and pathogenicities. Further tandem mass spectrometric analysis demonstrated that the nature of the C(inf15:0) fatty acid isomer (branched or normal) present in the mass spectrum of each microorganism was important for achieving the classification into three clusters.

Journal Article↗
PubMed1997

Application of microautoradiography to the study of substrate uptake by filamentous microorganisms in activated sludge.

Excessive growth of filamentous microorganisms in activated-sludge treatment plants is a major operational problem which causes poor settlement of activated sludge. An enhanced understanding of the factors controlling growth of different filamentous microorganisms is necessary in order to establish more successful control strategies. In the present study, the in situ substrate uptake was investigated by means of microautoradiography. It was demonstrated that the uptake of labeled organic substrates by the filamentous microorganisms, during short-term incubation, could be detected by microautoradiography. Viability and respiratory activity of the filaments were also detected by reduction of CTC (5-cyano-2,3-ditolyl tetrazolium chloride) and by incorporation of [(sup3)H]thymidine. Gram, Neisser, and fluorescence staining techniques were used for the localization and identification of the filaments. Activated-sludge samples from five wastewater treatment plants with bulking problems due to filamentous microorganisms were investigated. Microthrix parvicella, Nostocoida limicola, and Eikelboom's type 0041 and type 021N were investigated for their ability to take up organic substrates. A panel of six substrates, i.e., [(sup14)C]acetate, [(sup3)H]glucose, [(sup14)C]ethanol, [(sup3)H]glycine, [(sup3)H]leucine, and [(sup3)H]oleic acid, was tested. The uptake response was found to be very specific not only between the different filamentous types but also among filaments of the same type from different treatment plants. Interestingly, M. parvicella consistently took up only oleic acid among the tested substrates. It is concluded that microautoradiography is a useful method for investigation of in situ substrate uptake by filamentous microorganisms in activated sludge.

Journal Article↗
PubMed1998

Degradation of phthalate and Di-(2-Ethylhexyl)phthalate by indigenous and inoculated microorganisms in sludge-amended soil

The metabolism of phthalic acid (PA) and di-(2-ethylhexyl)phthalate (DEHP) in sludge-amended agricultural soil was studied with radiotracer techniques. The initial rates of metabolism of PA and DEHP (4.1 nmol/g [dry weight]) were estimated to be 731.8 and 25.6 pmol/g (dry weight) per day, respectively. Indigenous microorganisms assimilated 28 and 17% of the carbon in [14C]PA and [14C]DEHP, respectively, into microbial biomass. The rates of DEHP metabolism were much greater in sludge assays without soil than in assays with sludge-amended soil. Mineralization of [14C]DEHP to 14CO2 increased fourfold after inoculation of sludge and soil samples with DEHP-degrading strain SDE 2. The elevated mineralization potential was maintained for more than 27 days. Experiments performed with strain SDE 2 suggested that the bioavailability and mineralization of DEHP decreased substantially in the presence of soil and sludge components. The microorganisms metabolizing PA and DEHP in sludge and sludge-amended soil were characterized by substrate-specific radiolabelling, followed by analysis of 14C-labelled phospholipid ester-linked fatty acids (14C-PLFAs). This assay provided a radioactive fingerprint of the organisms actively metabolizing [14C]PA and [14C]DEHP. The 14C-PLFA fingerprints showed that organisms with different PLFA compositions metabolized PA and DEHP in sludge-amended soil. In contrast, microorganisms with comparable 14C-PLFA fingerprints were found to dominate DEHP metabolism in sludge and sludge-amended soil. Our results suggested that indigenous sludge microorganisms dominated DEHP degradation in sludge-amended soil. Mineralization of DEHP and PA followed complex kinetics that could not be described by simple first-order equations. The initial mineralization activity was described by an exponential function; this was followed by a second phase that was described best by a fractional power function. In the initial phase, the half times for PA and DEHP in sludge-amended soil were 2 and 58 days, respectively. In the late phase of incubation, the apparent half times for PA and DEHP increased to 15 and 147 days, respectively. In the second phase (after more than 28 days), the half time for DEHP was 2.9 times longer in sludge-amended soil assays than in sludge assays without soil. Experiments with radiolabelled DEHP degraders suggested that a significant fraction of the 14CO2 produced in long-term degradation assays may have originated from turnover of labelled microbial biomass rather than mineralization of [14C]PA or [14C]DEHP. It was estimated that a significant amount of DEHP with poor biodegradability and extractability remains in sludge-amended soil for extended periods of time despite the presence of microorganisms capable of degrading the compound (e.g., more than 40% of the DEHP added is not mineralized after 1 year).

Journal Article↗
PubMed1966

Influence of food microorganisms on staphylococcal growth and enterotoxin production in meat.

Forty-four microorganisms were studied for their influence on staphylococcal growth and enterotoxin production. Inhibition was found to be more common than stimulation. Two types of inhibition were observed: inhibition of staphylococcal growth, and inhibition of enterotoxin formation with no apparent effect on growth. By use of a plate test, 12 of the 44 food microorganisms were found to inhibit staphylococcal growth at 35 C. Of the 12, 3 also inhibited growth at 25 C. No significant differences in inhibition were observed with the 15 strains of enterotoxigenic staphylococci. In meat slurries, inhibition of staphylococcal growth was found to be greater at 25 C than at 35 C. Results on inhibition obtained from the plate test could not be correlated with the effect of the organisms in slurries. Environmental conditions were found to affect markedly the influence of food microorganisms on staphylococci. Of the 44 food microorganisms studied, only Bacillus cereus was observed to stimulate significantly staphylococcal growth and enterotoxin formation. Stimulation was more pronounced with Staphylococcus aureus 196E than with other strains of enterotoxigenic staphylococci. Bacillus megaterium and Brevibacterium linens were inhibited by staphylococci. These organisms were completely inhibited when inoculated in mixed cultures with staphylococci. In pure cultures, good staphylococcal growth was found to be accompanied by enterotoxin production; however, in the presence of food microorganisms, good staphylococcal growth occurred without the formation of detectable levels of enterotoxin A.

Bacteria↗
PubMed1970

Interenvironmental transfer of microorganisms on the exterior surfaces of jet aircraft.

The likelihood of microorganisms being transferred to new environments by jet aircraft was investigated. Initial random sampling of the aircraft surface revealed the presence of microorganisms in varying numbers on different aerodynamic surfaces. Bacteria of the genus Bacillus were the most common isolates, comprising approximately one-third of the total organisms found. The most frequently isolated fungi were Cladosporium, Alternaria, Penicillium, and several yeasts. Sampling of surfaces before and immediately after a flight demonstrated that microorganisms were collected during flight in areas protected from the airstream and lost in those areas directly exposed to it. These experiments also showed that the majority of the organisms contaminating the aircraft were acquired from the air at ground level. The placement of microorganisms on the aircraft surface before a flight and determination of their survival after flight indicated that the test organisms were most likely to be transported in the areas protected from the airstream. The organisms showing the best chance of being transferred seem to be the sporeforming bacteria, arthrospore-forming fungi, and some yeasts. All phases of this work showed that microorganisms could be carried by jet aircraft to environments they could not reach by natural means of dispersal.

Air Microbiology↗
PubMed2005

Characteristics and adaptability of iron- and sulfur-oxidizing microorganisms used for the recovery of metals from minerals and their concentrates.

Microorganisms are used in large-scale heap or tank aeration processes for the commercial extraction of a variety of metals from their ores or concentrates. These include copper, cobalt, gold and, in the past, uranium. The metal solubilization processes are considered to be largely chemical with the microorganisms providing the chemicals and the space (exopolysaccharide layer) where the mineral dissolution reactions occur. Temperatures at which these processes are carried out can vary from ambient to 80 degrees C and the types of organisms present depends to a large extent on the process temperature used. Irrespective of the operation temperature, biomining microbes have several characteristics in common. One shared characteristic is their ability to produce the ferric iron and sulfuric acid required to degrade the mineral and facilitate metal recovery. Other characteristics are their ability to grow autotrophically, their acid-tolerance and their inherent metal resistance or ability to acquire metal resistance. Although the microorganisms that drive the process have the above properties in common, biomining microbes usually occur in consortia in which cross-feeding may occur such that a combination of microbes including some with heterotrophic tendencies may contribute to the efficiency of the process. The remarkable adaptability of these organisms is assisted by several of the processes being continuous-flow systems that enable the continual selection of microorganisms that are more efficient at mineral degradation. Adaptability is also assisted by the processes being open and non-sterile thereby permitting new organisms to enter. This openness allows for the possibility of new genes that improve cell fitness to be selected from the horizontal gene pool. Characteristics that biomining microorganisms have in common and examples of their remarkable adaptability are described.

Journal Article↗