Purification and characterization of a novel biosurfactant produced by Bacillus licheniformis MS3

Bacillus lipopeptides as key players in rhizosphere chemical ecology

Microbial natural products are widely explored for their therapeutic potential. Understanding the underlying evolutionary and adaptive forces driving their production remains a fundamental question in biology. Amphiphilic cyclic lipopeptides (CLPs), a prominent category of bacterial specialized metabolites, show strong antimicrobial activity, particularly against phytopathogens. It is thus assumed that these compounds are deployed by soil- or rhizosphere-dwelling bacteria as microbial weapons in competitive natural environments. Here, we challenge this reductionist perspective and present evidence that Bacillus CLPs are prominent chemical mediators of ecological interactions. They help Bacillus to communicate, compete, defend against predators, or cooperate and establish mutualistic relationships with other (micro)organisms. Additional parallel examples are highlighted in other genera, such as Pseudomonas. This broader perspective underscores the need for further investigation into the role of CLPs in shaping the adaptive strategies of key rhizobacterial species.

Bacillus licheniformis: A Producer of Antimicrobial Substances, including Antimycobacterials, Which Are Feasible for Medical Applications

Bacillus licheniformis produces several classes of antimicrobial substances, including bacteriocins, which are peptides or proteins with different structural composition and molecular mass: ribosomally synthesized by bacteria (1.4-20 kDa), non-ribosomally synthesized peptides and cyclic lipopeptides (0.8-42 kDa) and exopolysaccharides (>1000 kDa). Different bacteriocins act against Gram-positive or Gram-negative bacteria, fungal pathogens and amoeba cells. The main mechanisms of bacteriocin lytic activity include interaction of peptides with membranes of target cells resulting in structural alterations, pore-forming, and inhibition of cell wall biosynthesis. DNase and RNase activity for some bacteriocines are also postulated. Non-ribosomal peptides are synthesized by special non-ribosomal multimodular peptide synthetases and contain unnatural amino acids or fatty acids. Their harmful effect is due to their ability to form pores in biological membranes, destabilize lipid packaging, and disrupt the peptidoglycan layer. Lipopeptides, as biosurfactants, are able to destroy bacterial biofilms. Secreted polysaccharides are high molecular weight compounds, composed of repeated units of sugar moieties attached to a carrier lipid. Their antagonistic action was revealed in relation to bacteria, viruses, and fungi. Exopolysaccharides also inhibit the formation of biofilms by pathogenic bacteria and prevent their colonization on various surfaces. However, mechanism of the harmful effect for many secreted antibacterial substances remains unknown. The antimicrobial activity for most substances has been studied in vitro only, but some substances have been characterized in vivo and they have found practical applications in medicine and veterinary. The cyclic lipopeptides that have surfactant properties are used in some industries. In this review, special attention is paid to the antimycobacterials produced by B. licheniformis as a possible approach to combat multidrug-resistant and latent tuberculosis. In particular, licheniformins and bacitracins have shown strong antimycobacterial activity. However, the medical application of some antibacterials with promising in vitro antimycobacterial activity has been limited by their toxicity to animals and humans. As such, similar to the enhancement in the antimycobacterial activity of natural bacteriocins achieved using genetic engineering, the reduction in toxicity using the same approach appears feasible. The unique capability of B. licheniformis to synthesize and produce a range of different antibacterial compounds means that this organism can act as a natural universal vehicle for antibiotic substances in the form of probiotic cultures and strains to combat various types of pathogens, including mycobacteria.

New aspects of lipopeptide-incorporated nanoparticle synthesis and recent advancements in biomedical and environmental sciences: a review

The toxicity of metal nanoparticles has introduced promising research in the current scenario since an enormous number of people have been potentially facing this problem in the world. The extensive attention on green nanoparticle synthesis has been focussed on as a vital step in bio-nanotechnology to improve biocompatibility, biodegradability, eco-friendliness, and huge potential utilization in various environmental and clinical assessments. Inherent influence on the study of green nanoparticles plays a key role to synthesize the controlled and surface-influenced molecule by altering the physical, chemical, and biological assets with the provision of various precursors, templating/co-templating agents, and supporting solvents. However, in this article, the dominant characteristics of several kinds of lipopeptide biosurfactants are discussed to execute a critical study of factors affecting synthesis procedure and applications. The recent approaches of metal, metal oxide, and composite nanomaterial synthesis have been deliberated as well as the elucidation of the reaction mechanism. Furthermore, this approach shows remarkable boosts in the production of nanoparticles with the very less employed harsh and hazardous processes as compared to chemical or physical method-based nanoparticle synthesis. This study also shows that the advances in strain selection for green nanoparticle production could be a worthwhile and strong economical approach in futuristic medical science research.

Production, characterization and bio-emulsifying application of exopolysaccharides from Rhodotorula mucilaginosa YMM19

Microbial exopolysaccharides (EPS) are high molecular weight polymers having different sugar residues. EPS have potential applications in different fields, such as medicine, food and environment. Therefore, there is a growing interest in production, characterization and application of EPS from different microorganisms. The present study designed to investigate the production and characterization of EPS from Rhodotorula mucilaginosa YMM19 isolated from Morus nigra L. fruits as well as to examine their potential emulsifying properties. Effect of NaCl concentration, incubation period and pH on the production of EPS was studied. The maximum EPS production by yeast was achieved at 10% NaCl (9741.84 mg/l). The best incubation time for production of EPS was 5 days. Production of EPS decreased under neutral condition and increased at acidic and alkaline condition. The structural feature of EPS was examined by FT-IR and NMR spectral analysis and confirmed the presence of glucose, glucopyranose and galactose. The isolated EPS showed higher emulsification capacity with emulsification activity of 71% and emulsifying index of 60%. The EPS gave strong emulsification for farnesol and was more effective than sodium dodecyl sulphate, a reference emulsifier, in enhancing the herbicidal activity of farnesol against Melilotus indicus under greenhouse condition. The results suggest that the EPS produced by YMM19 strain has a potential to be used as emulsifying agent in pesticide formulations.

Effect of inorganic nutrients on bacterial community composition in oil-bearing sandstones from the subsurface strata of an onshore oil reservoir and its potential use in Microbial Enhanced Oil Recovery

Microbial Enhanced Oil Recovery (MEOR) is a promising strategy to improve recovery of residual oil in reservoirs, which can be performed by promoting specific indigenous microorganisms. In this study, we performed preliminary evaluation of the possibility of conducting MEOR at Mae Soon reservoir, an onshore reservoir in Northern Thailand. The reservoir’s physicochemical characteristics, including the characteristics of the wells, the oil-bearing sandstone cores, and the reservoir’s produced water, were determined. The microbiological characteristics of the oil wells in the reservoir were also investigated by submerging the reservoir’s sandstone core samples, obtained from 6 oil wells, in the reservoir’s produced water and in the produced water added with inorganic nutrients (KNO₃ and NaH₂PO₄). The uncultured bacteria in both treatments were determined, using tagged 16S rRNA gene amplicon with Ion Torrent Sequencing Analysis. The effects of inorganic nutrients and the reservoir’s parameters on the bacterial communities were analysed. A total number of 16,828 OTUs were taxonomically classified into 89 classes and 584 genera. In the controls (sandstone cores submerged in the produced water), the dominant bacterial populations were related to Deinococcus-Thermus, and Betaproteobacteria; while in the nutrient treated samples, there was a marked increase in the relative abundance of Gammaproteobacteria in three samples. Thermus, Acinetobacter, and Pseudomonas were the most abundant genera, and these are potential microorganisms for MEOR. Analysis of correlations between physiochemical properties of the reservoir and bacterial genera, using spearman’s correlation analysis, suggested that some of the reservoir’s properties, especially of the well and the rock, could influence some bacterial genera. To our knowledge, this is the first demonstration of the effect of inorganic nutrients on alteration of bacterial communities attached to reservoir’s rock, and how the bacterial, physical, and chemical properties of a reservoir were co-analysed to serve as a basis for designing a MEOR process.

Preliminary characterization of biosurfactant produced by a PAH-degrading Paenibacillus sp. under thermophilic conditions

The capacities of a biosurfactant producing and polycyclic aromatic hydrocarbon (PAH) utilizing bacterium, namely, strain 1C, isolated from an Algerian contaminated soil, were investigated. Strain 1C belonged to the Paenibacillus genus and was closely related to the specie Paenibacillus popilliae, with 16S rRNA gene sequence similarity of 98.4 %. It was able to produce biosurfactant using olive oil as substrate. The biosurfactant production was shown by surface tension (32.6 mN/m) after 24 h of incubation at 45 °C and 150 rpm. The biosurfactant(s) retained its properties during exposure to elevated temperatures (70 °C), relatively high salinity (20 % NaCl), and a wide range of pH values (2-10). The infrared spectroscopy (FTIR) revealed that its chemical structure belonged to lipopeptide class. The critical micelle concentration (CMC) of this biosurfactant was about 0.5 g/l with 29.4 mN/m. In addition, the surface active compound(s) produced by strain 1C enhanced PAH solubility and showed a significant antimicrobial activity against pathogens. In addition to its biosurfactant production, strain 1C was shown to be able to utilize PAHs as the sole carbon and energy sources. Strain 1C as hydrocarbonoclastic bacteria and its interesting surface active agent may be used for cleaning the environments polluted with polyaromatic hydrocarbons.

Properties of Polyhydroxyalkanoate Granules and Bioemulsifiers from Pseudomonas sp. and Burkholderia sp. Isolates Growing on Glucose

A Burkholderia and Pseudomonas species designated as AB4 and AS1, respectively, were isolated from soil containing decomposing straw or sugar cane bagasse collected from Brazil. This study sought to evaluate the capacities of culture media, cell-free medium, and crude lysate preparations (containing PHB inclusion bodies) from bacterial cell cultures to stabilize emulsions with several hydrophobic compounds. Four conditions showed good production of bioemulsifiers (E24 ≥ 50 %), headed by substantially cell-free media from bacterial cell cultures in which bacterial isolates from Burkholderia sp. strain AB4 and Pseudomonas sp. strain AS1 were grown. Our results revealed that the both isolates (AB4 and AS1 strains) exhibited high emulsification indices (indicating usefulness in bioremediation) and good stabilities.

Isolation and purification of a new enamide biosurfactant from Fusarium proliferatum using rice-bran

A new fungusFusarium proliferatumwas isolated from the oil contaminated sludge of the rice-bran oil industry, which was capable of producing biosurfactants when grown on rice-bran.

Exopolysaccharides and antimicrobial biosurfactants produced by Paenibacillus macerans TKU029

Paenibacillus macerans TKU029 can produce exopolysaccharides (EPSs; 3.46 g/L) and a biosurfactant (1.78 g/L) in a medium with 2 % (w/v) squid pen powder as the sole carbon/nitrogen source. The biosurfactant can reduce the surface tension of water from 72.30 to 35.34 mN/m at a concentration of 2.76 g/L and reach an emulsification index of 56 % after a 24-h reaction with machine oil. This biosurfactant is stable at 121 °C for 20 min, over a pH range from 3 to 11, and in <5 % salt solutions. It also shows significant antimicrobial activity, which remains active after treatment at 121 °C and at pH values from 4 to 10, against Escherichia coli BCRC13086, Staphylococcus aureus BCRC10780, Fusarium oxysporum BCRC32121 and Aspergillus fumigatus BCRC30099. Furthermore, human skin shows from 37.3 to 44.3 % hydration after being treated with TKU029 EPSs for 180 min. These results imply that EPSs and the biosurfactant from this strain have potential in cosmetics, for removal of oil contamination, and as antimicrobial agents.

phoRsequences as a phylogenetic marker to differentiate the species in theBacillus subtilisgroup

Bacillus subtilis and its closely related species are indistinguishable from one another by morphological characteristics and 16S rDNA sequences. In this study, the partial phoR sequence was tested to determine the phylogenetic relationship of species in the B. subtilis group. Degenerate primers were developed according to the relatively conserved nucleotide sequences of phoR and the linked gene phoP in the B. subtilis group. The primers amplified a 1100 bp phoR fragment from strains representative of 6 species in the B. subtilis group. Based on the sequenced fragments, 26 type strains comprising these 6 species were clearly distinguished. At the intraspecies level, the phoR sequence similarities were 90%–100%, but at the interspecies level, the phoR sequence similarities were 32.8%–75%. Compared with the gyrB sequence, the phoR sequences showed a larger divergence especially at the interspecies levels. Therefore, the phoR sequence may be an efficient alternative marker for phylogenetic and taxonomic analysis of species in the B. subtilis group. Twenty-three Bacillus undomesticated isolates were tested for identification and phylogenetic analysis based on the phoR and gyrB sequences. The 23 isolates could be clearly delineated into 4 distinct groups, 10 as B. subtilis, 3 as B. mojavensis, 2 as B. atrophaeus, and 8 as B. amyloliquefaciens.