Dataset Information

Leptothrix cholodnii Response to Nutrient Limitation.

ABSTRACT: Microorganisms are widely utilized for the treatment of wastewater in activated sludge systems. However, the uncontrolled growth of filamentous bacteria leads to bulking and adversely affects wastewater treatment efficiency. To clarify the nutrient requirements for filament formation, we track the growth of a filamentous bacterium, Leptothrix cholodnii SP-6 in different nutrient-limited conditions using a high aspect-ratio microfluidic chamber to follow cell-chain elongation and sheath formation. We find that limitations in Na⁺, K⁺, and Fe²⁺ yield no observable changes in the elongation of cell chains and sheath formation, whereas limitations of C, N, P, or vitamins lead to more pronounced changes in filament morphology; here we observe the appearance of partially empty filaments with wide intercellular gaps. We observe more dramatic differences when SP-6 cells are transferred to media lacking Mg²⁺ and Ca²⁺. Loss of Mg²⁺ results in cell autolysis, while removal of Ca²⁺ results in the catastrophic disintegration of the filaments. By simultaneously limiting both carbon and Ca²⁺ sources, we are able to stimulate planktonic cell generation. These findings paint a detailed picture of the ecophysiology of Leptothrix, which may lead to improved control over the unchecked growth of deleterious filamentous bacteria in water purification systems.

SUBMITTER: Kunoh T

PROVIDER: S-EPMC8264430 | biostudies-literature | 2021

REPOSITORIES: biostudies-literature

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<i>Leptothrix cholodnii</i> Response to Nutrient Limitation.

Kunoh Tatsuki T Yamamoto Tatsuya T Sugimoto Shinya S Ono Erika E Nomura Nobuhiko N Utada Andrew S AS

Frontiers in microbiology 20210624

Microorganisms are widely utilized for the treatment of wastewater in activated sludge systems. However, the uncontrolled growth of filamentous bacteria leads to bulking and adversely affects wastewater treatment efficiency. To clarify the nutrient requirements for filament formation, we track the growth of a filamentous bacterium, <i>Leptothrix cholodnii</i> SP-6 in different nutrient-limited conditions using a high aspect-ratio microfluidic chamber to follow cell-chain elongation and sheath fo ...[more]

PMID: 34248917

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Project description:Mounting evidence demonstrates that nutritional environment can alter pathogen drug sensitivity. While the rich media used for in vitro culture contains supraphysiological nutrient concentrations, pathogens encounter a relatively restrictive environment in vivo. We assessed the effect of nutrient limitation on the protozoan parasite that causes malaria and demonstrated that short-term growth under physiologically relevant mild nutrient stress (or "metabolic priming") triggers increased tolerance of a potent antimalarial drug. We observed beneficial effects using both short-term survival assays and longer-term proliferation studies, where metabolic priming increases parasite survival to a level previously defined as resistant (>1% survival). We performed these assessments by either decreasing single nutrients that have distinct roles in metabolism or using a media formulation that simulates the human plasma environment. We determined that priming-induced tolerance was restricted to parasites that had newly invaded the host red blood cell, but the effect was not dependent on genetic background. The molecular mechanisms of this intrinsic effect mimic aspects of genetic tolerance, including translational repression and protein export. This finding suggests that regardless of the impact on survival rates, environmental stress could stimulate changes that ultimately directly contribute to drug tolerance. Because metabolic stress is likely to occur more frequently in vivo compared to the stable in vitro environment, priming-induced drug tolerance has ramifications for how in vitro results translate to in vivo studies. Improving our understanding of how pathogens adjust their metabolism to impact survival of current and future drugs is an important avenue of research to slow the evolution of resistance. IMPORTANCE There is a dire need for effective treatments against microbial pathogens. Yet, the continuing emergence of drug resistance necessitates a deeper knowledge of how pathogens respond to treatments. We have long appreciated the contribution of genetic evolution to drug resistance, but transient metabolic changes that arise in response to environmental factors are less recognized. Here, we demonstrate that short-term growth of malaria parasites in a nutrient-limiting environment triggers cellular changes that lead to better survival of drug treatment. We found that these strategies are similar to those employed by drug-tolerant parasites, which suggests that starvation "primes" parasites to survive and potentially evolve resistance. Since the environment of the human host is relatively nutrient restrictive compared to growth conditions in standard laboratory culture, this discovery highlights the important connections among nutrient levels, protective cellular pathways, and resistance evolution.

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Leptothrix cholodnii Response to Nutrient Limitation.

Publications

<i>Leptothrix cholodnii</i> Response to Nutrient Limitation.

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