Nutrient Sensing and Biofilm Modulation: The Example of L-arginine in Pseudomonas

Abstract

Bacterial biofilm represents a multicellular community embedded within an extracellular matrix attached to a surface. This lifestyle confers to bacterial cells protection against hostile environments, such as antibiotic treatment and host immune response in case of infections. The Pseudomonas genus is characterised by species producing strong biofilms difficult to be eradicated and by an extraordinary metabolic versatility which may support energy and carbon/nitrogen assimilation under multiple environmental conditions. Nutrient availability can be perceived by a Pseudomonas biofilm which, in turn, readapts its metabolism to finally tune its own formation and dispersion. A growing number of papers is now focusing on the mechanism of nutrient perception as a possible strategy to weaken the biofilm barrier by environmental cues. One of the most important nutrients is amino acid L-arginine, a crucial metabolite sustaining bacterial growth both as a carbon and a nitrogen source. Under low-oxygen conditions, L-arginine may also serve for ATP production, thus allowing bacteria to survive in anaerobic environments. L-arginine has been associated with biofilms, virulence, and antibiotic resistance. L-arginine is also a key precursor of regulatory molecules such as polyamines, whose involvement in biofilm homeostasis is reported. Given the biomedical and biotechnological relevance of biofilm control, the state of the art on the effects mediated by the L-arginine nutrient on biofilm modulation is presented, with a special focus on the Pseudomonas biofilm. Possible biotechnological and biomedical applications are also discussed.

Gene expression reprogramming of Pseudomonas alloputida in response to arginine through the transcriptional regulator ArgR

“…A number of genes previously reported to be differentially expressed in a mutant in which the roxSR operon was disrupted [49], including argT and argG, showed also differential expression in the ΔargR mutant with respect to the wild-type strain (Table 1). These results support a connection between redox and arginine signalling, similar to what has been suggested in P. aeruginosa regarding the phosphodiesterase RmcA [10,51] and add weight to data on the relevance of ArgR for maintaining the metabolic activity of P. putida biofilms [25].…”

Extracellular Vehicles from Commensal Skin Malassezia restricta Inhibit Staphylococcus aureus Proliferation and Biofilm Formation

“…Specifically, l -arginine undergoes conversion to l -citrulline and NO through nitric oxide synthase, resulting in citrullination . The inhibition of arginine synthesis and subsequent disturbance of the tricarboxylate cycle and DNA damage can be attributed to the downregulation of l -glutamic acid, n -acetyl- l -glutamic acid, n-acetylornithine, n -acetyl- l -citrulline, and l -ornithine. , A reduction in l -arginine may decrease the ability of bacteria to form biofilms, which aligns with the above findings. In general, the experimental results can support each other and jointly suggest that the EVs of M.…”

Changes in Metal-Chelating Metabolites Induced by Drought and a Root Microbiome in Wheat

“…Maintenance of root hairs would be an important process to ensure water and nutrient uptake during drought [ 61 ]. The bacterium also could use arginine to generate polyamines that would stimulate their biofilm formation [ 62 ] and drought stress tolerance in the plant [ 63 ]. Secretion of betaine in the rhizosphere solution may be a ploy by the plant to maintain the beneficial microbe under drought conditions.…”