Dataset Information

CO2 production as an indicator of biofilm metabolism.

ABSTRACT: Biofilms are important in aquatic nutrient cycling and microbial proliferation. In these structures, nutrients like carbon are channeled into the production of extracellular polymeric substances or cell division; both are vital for microbial survival and propagation. The aim of this study was to assess carbon channeling into cellular or noncellular fractions in biofilms. Growing in tubular reactors, biofilms of our model strain Pseudomonas sp. strain CT07 produced cells to the planktonic phase from the early stages of biofilm development, reaching pseudo steady state with a consistent yield of approximately 10(7) cells.cm(-2).h(-1) within 72 h. Total direct counts and image analysis showed that most of the converted carbon occurred in the noncellular fraction, with the released and sessile cells accounting for <10% and <2% of inflowing carbon, respectively. A CO(2) evolution measurement system (CEMS) that monitored CO(2) in the gas phase was developed to perform a complete carbon balance across the biofilm. The measurement system was able to determine whole-biofilm CO(2) production rates in real time and showed that gaseous CO(2) production accounted for 25% of inflowing carbon. In addition, the CEMS made it possible to measure biofilm response to changing environmental conditions; changes in temperature or inflowing carbon concentration were followed by a rapid response in biofilm metabolism and the establishment of new steady-state conditions.

SUBMITTER: Kroukamp O

PROVIDER: S-EPMC2704800 | biostudies-other | 2009 Jul

REPOSITORIES: biostudies-other

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CO2 production as an indicator of biofilm metabolism.

Kroukamp Otini O Wolfaardt Gideon M GM

Applied and environmental microbiology 20090403 13

Biofilms are important in aquatic nutrient cycling and microbial proliferation. In these structures, nutrients like carbon are channeled into the production of extracellular polymeric substances or cell division; both are vital for microbial survival and propagation. The aim of this study was to assess carbon channeling into cellular or noncellular fractions in biofilms. Growing in tubular reactors, biofilms of our model strain Pseudomonas sp. strain CT07 produced cells to the planktonic phase f ...[more]

PMID: 19346353

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Project description:Among all the essential micronutrients, iron plays an important role in mammalian biology. It is also essential for pathogens infecting mammalian hosts, including bacteria, fungi, and protozoans. As the availability of accessible iron is limited within the mammalian host, several human-pathogenic fungal pathogens, such as Candida albicans, Cryptococcus neoformans, Candida glabrata, and Aspergillus fumigatus, have developed various iron uptake mechanisms. Although Candida parapsilosis is the second or third most common non-albicans Candida species associated with systemic and superficial Candida infections in immunocompromised patients, the mechanisms of iron uptake and homoeostasis remain unknown in this fungus. In the current report, we show that a homologue of the multicopper oxidase gene FET3 is present in the genome of C. parapsilosis (CPAR2_603600) and plays a significant role in iron acquisition. We found that homozygous deletion mutants of CPAR2_603600 showed defects under low-iron conditions and were also sensitive to various stressors. Our results also revealed that the levels of pseudohypha formation and biofilm formation were reduced in the null mutants compared to the wild type. This phenotypic defect could be partially rescued by supplementation with excess iron in the growth medium. The expression levels of the orthologues of various iron metabolism-related genes were also altered in the mutants compared to the parental strain. In conclusion, our report describes the role of CPAR2_603600 in iron homoeostasis maintenance as well as morphology and biofilm formation regulation in this pathogenic fungus.IMPORTANCE C. parapsilosis is the second or third most common opportunistic human-pathogenic Candida species, being responsible for severe fungal infections among immunocompromised patients, especially low-birth-weight infants (0 to 2 years of age). Among the major virulence factors that pathogenic fungi possess is the ability to compete with the host for essential micronutrients, including iron. Accessible iron is required for the maintenance of several metabolic processes. In order to obtain accessible iron from the host, pathogenic fungi have developed several iron acquisition and metabolic mechanisms. Although C. parapsilosis is a frequent cause of invasive candidiasis, little is known about what iron metabolic processes this fungus possesses that could contribute to the species' virulent behavior. In this study, we identified the multicopper oxidase FET3 gene that regulates iron homeostasis maintenance and also plays important roles in the morphology of the fungus as well as in biofilm formation, two additional factors in fungal virulence.

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CO2 production as an indicator of biofilm metabolism.

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CO2 production as an indicator of biofilm metabolism.

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