Simple method for quantification of anionic biosurfactants in aqueous solutions

Unlocking the Synergistic Potential and Efficacy of Biosurfactant-Silver Nanoparticle for Enhanced Antimicrobial Activities

Microorganisms can produce various amphiphilic compounds known as biosurfactants, with diverse applications in distinct industries. This study was focused on the biosurfactant production by Limosilactobacillus fermentum HBUAS62516 for the synthesis of silver nanoparticles. The biosurfactant obtained was characterized as glycolipid using FTIR which showed prominent peaks at 2932.3, 1116.3, and 1084.4 cm-1, indicating major functional groups which was further confirmed using techniques, such as EDS, NMR, and HPLC. Biosurfactant was utilized as the reducing agent for the biosynthesis of silver nanoparticles which was confirmed using UV-Vis spectral measurements that showed maximum absorbance at 421 nm and FTIR revealed peaks at 109 and 665 cm-1, indicating silver nanoparticle formation. EDS confirmed the presence of silver nanoparticles with a mass percentage of 100.00 ± 4.56%. Dynamic light scattering (DLS) and zeta potential were 87.93 nm and - 21 mV, respectively, indicating stability. The nanoparticles showed significant antibiofilm and antioxidant activity (90.1%). The synergistic antibacterial effect of the biosurfactant and nanoparticles was studied against Staphylococcus aureus and Pseudomonas putida, as well as their antifungal activity against Aspergillus niger, with a MIC value of 12.5 μg/mL. Nanoparticles synthesized using biosurfactants obtained from probiotic bacteria can act as alternative therapeutics to treat infections caused by the biofilm-forming bacteria.

Rhamnolipids bio-production and miscellaneous applications towards green technologies: a literature review

Growing attention towards rhamnolipids (RLs) biosurfactants with antibacterial, antifungal, antivirus and antitumor potentials encourage future research in biotechnology and biomedicine fields. Economic production from waste materials, biodegradability and low toxicity makes RLs perform as green molecules that serve in sustainability and green technologies. This review aims to focus on bioproduction, detection and applications of rhamnolipids in pharmaceuticals, soil bioremediation, agriculture and food industries in addition to future perspectives. This will help to shed light on and update the existing knowledge of feasible and sustainable biosurfactant production depending on the fermentation processes.

Assessing hydrocarbon degradation capacity of Isoptericola peretonis sp. nov. and related species: a comparative study

Since the beginning of their production and use, fossil fuels have affected ecosystems, causing significant damage to their biodiversity. Bacterial bioremediation can provide solutions to this environmental problem. In this study, the new species Isoptericola peretonis sp. nov. 4D.3T has been characterized and compared to other closely related species in terms of hydrocarbon degradation and biosurfactant production by in vitro and in silico analyses. Biosurfactants play an important role in microbial hydrocarbon degradation by emulsifying hydrocarbons and making them accessible to the microbial degradation machinery. The tests performed showed positive results to a greater or lesser degree for all strains. In the synthesis of biosurfactants, all the strains tested showed biosurfactant activity in three complementary assays (CTAB, hemolysis and E24%) and rhamnolipid synthesis genes have been predicted in silico in the majority of Isoptericola strains. Regarding hydrocarbon degradation, all the Isoptericola strains analyzed presented putative genes responsible for the aerobic and anaerobic degradation of aromatic and alkane hydrocarbons. Overall, our results highlight the metabolic diversity and the biochemical robustness of the Isoptericola genus which is proposed to be of interest in the field of hydrocarbon bioremediation.

Anti-Fungal (Aspergillus fumigatus) Activity of Pseudomonas aeruginosa in Cystic Fibrosis Synthetic Sputum

Aspergillus fumigatus (Af) and Pseudomonas aeruginosa (Pa) are pathogens inhabiting the lungs of persons with cystic fibrosis (CF), or immune-compromised patients, causing or aggravating disease. We previously investigated their microbial interaction as well as susceptibility to anti-fungal drugs using RPMI medium (contains undetectable iron concentrations), as is standard for susceptibility testing. Here we investigated microbial interaction in synthetic sputum medium (SSPM), a complex mixture designed to mimic the milieu in CF lungs. SSPM contains Fe2+. Pa laboratory strain PA14 or PA14 siderophore mutant planktonic culture filtrate, prepared in RPMI or SSPM, were compared for inhibition of Af biofilm formation. SSPM enhanced bacterial and fungal growth and the production of the Pa molecules pyoverdine, phenazines, and rhamnolipids. Af was more susceptible to these molecules in SSPM (with the exception of pyoverdine). SSPM interfered with fungal susceptibility to pyoverdine. Studies with the mutant helped to reveal that the reduced anti-fungal activity of pyoverdine in SSPM appears to be compensated by higher production of other anti-fungal molecules, e.g., rhamnolipids, phenazines, and PQS, and higher Af sensitivity to these molecules. In summary, SSPM better defines Pa-Af intermicrobial competition in the milieu of CF lungs.

Alternative method for rhamnolipids quantification using an electrochemical platform based on reduced graphene oxide, manganese nanoparticles and molecularly imprinted Poly(L-Ser)

Rhamnolipids (RHLs) are promising biosurfactants with important applications in several industrial segments. These compounds are produced through biotechnological processes using the bacteria Pseudomonas Aeruginosa. The main methods of analyzing this compound are based on chromatographic techniques. In this study, an electrochemical sensor based on a platform modified with reduced graphene oxide, manganese nanoparticles covered with a molecularly imprinted poly (L-Ser) film was used as an alternative method to quantify RHL through its hydrolysis product, acid 3-hydroxydecanoic acid (3-HDA). The proposed sensor was characterized microscopically, spectroscopically and electrochemically. Under optimized experimental conditions, an analytical curve was obtained in the linear concentration range from 2.0 × 10-12 mol L-1 to 1.0 × 10-10 mol L-1. The values estimated of LOD, LOQ and AS were 8.3 × 10-13 mol L-1, 2.7 × 10-12 mol L-1and 1.3 × 107 A L mol-1, respectively. GCE/rGO/MnNPs/L-Ser@MIP exhibits excellent selectivity, repeatability, and high stability for the detection of 3-HDA. Furthermore, the developed method was successfully applied to the recognition of the hydrolysis product (3-HDA) of RHLs obtained from guava agro-waste. Statistical comparison between GCE/rGO/MnNPs/L-Ser@MIP and HPLC method confirms the accuracy of the electrochemical sensor within a 95% confidence interval.