Biofilms contain group(s) of microorganisms that are found to be associated with the biotic and abiotic surfaces. Biofilms contain either homogenous or heterogeneous populations of bacteria which remain in the matrix made up of extracellular polymeric substances secreted by constituent population of the biofilm. Biofilms can be either single or multilayered. Biofilms are an increasing issue of concern that is gaining importance with each passing day. Due to the ubiquitous nature of biofilms, it is difficult to eradicate them. It has been seen that many infectious diseases harbour biofilms of bacterial pathogens as the reservoir of persisting infections which can prove fatal at times. The presence of biofilms can be seen in diseases like endocarditis, cystic fibrosis, periodontitis, rhinosinusitis and osteomyelitis. The presence of biofilms has been mostly seen in medical implants and urinary catheters. Various signalling events including two-component signalling, extra cytoplasmic function and quorum sensing are involved in the formation of biofilms. The presence of an extracellular polymeric matrix in biofilms makes it difficult for the antimicrobials to act on them and make the bacteria tolerant to antibiotics and other drugs. The aim of this review was to discuss about the basic formation of a biofilm, various signalling cascades involved in biofilm formation, possible mechanisms of drug resistance in biofilms and recent therapeutic approaches involved in successful eradication of biofilms.

Siderophores are small organic molecules produced by microorganisms under iron-limiting conditions which enhance the uptake of iron to the microorganisms. In environment, the ferric form of iron is insoluble and inaccessible at physiological pH (7.35-7.40). Under this condition, microorganisms synthesize siderophores which have high affinity for ferric iron. These ferric iron-siderophore complexes are then transported to cytosol. In cytosol, the ferric iron gets reduced into ferrous iron and becomes accessible to microorganism. In recent times, siderophores have drawn much attention due to its potential roles in different fields. Siderophores have application in microbial ecology to enhance the growth of several unculturable microorganisms and can alter the microbial communities. In the field of agriculture, different types of siderophores promote the growth of several plant species and increase their yield by enhancing the Fe uptake to plants. Siderophores acts as a potential biocontrol agent against harmful phyto-pathogens and holds the ability to substitute hazardous pesticides. Heavy-metal-contaminated samples can be detoxified by applying siderophores, which explicate its role in bioremediation. Siderophores can detect the iron content in different environments, exhibiting its role as a biosensor. In the medical field, siderophore uses the "Trojan horse strategy" to form complexes with antibiotics and helps in the selective delivery of antibiotics to the antibiotic-resistant bacteria. Certain iron overload diseases for example sickle cell anemia can be treated with the help of siderophores. Other medical applications of siderophores include antimalarial activity, removal of transuranic elements from the body, and anticancer activity. The aim of this review is to discuss the important roles and applications of siderophores in different sectors including ecology, agriculture, bioremediation, biosensor, and medicine.

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A new strain of Pseudomonas has been isolated from soil that is able to adhere to PES and degrade this polymer efficiently. This organism has the potential to be implemented as a useful tool for bioremediation of PES-derived materials.