Screening, Isolation and Characterization of Aerobic Magnetotactic Bacteria From Western Ghats Forest Soil.

Magnetotactic bacteria (MTB) are a unique ecophysiological group of iron-metabolizing bacteria that have immense potential biotechnological applications. These bacteria have predominantly been isolated from oxygen-limited conditions of aquatic niches and rarely from the soils. The Western Ghats biodiversity hotspot has been well-studied for its fauna and flora diversity. The present study includes optimization of enrichment medium for cultivation of MTB, to suit aerobic mesophiles from forest soil. The major components included were Ferric quinate and Resazurin. The enrichment and isolates were characterized for their magnetic properties using magnetotaxis on agar plates, Vibrating Sampler Magnetometer (VSM), and X-ray diffraction (XRD) analysis. The isolates, namely Bacillus sp. S1 (MN212953), Sphingoaurantiacus sp. S2_03 (MN212954), Burkholderia sp. S2_08 (MN212955) and Microvirga sp. S2_09 (MN212956) were isolated and characterized to have a magnetosome size of 2.5-8 nm. Our study is the first report on the enrichment and isolation of MTB from Western Ghats forest soil. Supplementary Information: The online version contains supplementary material available at 10.1007/s12088-024-01316-4.

Comparative negation of amphiphile production using nutrition factors: Amyloids versus biosurfactants.

Microbial amphiphiles play an important role in environmental activities such as microbial signaling, bioremediation, and biofilm formation. Microorganisms rely on their unique characteristics of interfaces to carry out critical biological functions, which are helped by amphipathic biomolecules known as amphiphiles. Bacillus amyloids aid in cell adhesion and biofilm formation. Pseudomonas sp. are essential in biofilm development and are a vital survival strategy for many bacteria. Furthermore, Pseudomonas and Bacillus are well-known for their ability to produce biosurfactants with a range of applications, including bioremediation and removing biological pollutants from different environments. The study employed 31 different media types and a range of analytical techniques to assess the presence of amyloid proteins and the absence of biosurfactants in Bacillus licheniformis K125 (GQ850525.1) and Pseudomonas fluorescens CHA0. The presence of amyloid proteins was confirmed through Congo red and thioflavin T staining. The carefully constructed medium also efficiently inhibited the synthesis of biosurfactants by these bacteria. Additionally, surface tension measurements, emulsification index, thin-layer chromatography, and high-performance thin-layer chromatography analyses indicated the absence of biosurfactants in the tested media.

Importance of microbial amphiphiles: interaction potential of biosurfactants, amyloids, and other exo-polymeric-substances.

Microorganisms produce a diverse group of biomolecules having amphipathic nature (amphiphiles). Microbial amphiphiles, including amyloids, bio-surfactants, and other exo-polymeric substances, play a crucial role in various biological processes and have gained significant attention recently. Although diverse in biochemical composition, these amphiphiles have been reported for common microbial traits like biofilm formation and pathogenicity due to their ability to act as surface active agents with active interfacial properties essential for microbes to grow in various niches. This enables microbes to reduce surface tension, emulsification, dispersion, and attachment at the interface. In this report, the ecological importance and biotechnological usage of important amphiphiles have been discussed. The low molecular weight amphiphiles like biosurfactants, siderophores, and peptides showing helical and antimicrobial activities have been extensively reported for their ability to work as quorum-sensing mediators. While high molecular weight amphiphiles make up amyloid fibers, exopolysaccharides, liposomes, or magnetosomes have been shown to have a significant influence in deciding microbial physiology and survival. In this report, we have discussed the functional similarities and biochemical variations of several amphipathic biomolecules produced by microbes, and the present report shows these amphiphiles showing polyphyletic and ecophysiological groups of microorganisms and hence can `be replaced in biotechnological applications depending on the compatibility of the processes.

A review on biosurfactants: properties, applications and current developments.

Microbial surfactants are a large number of amphipathic biomolecules with a myriad of biomolecule constituents from various microbial sources that have been studied for their surface tension reduction activities. With unique properties, their applications have been increased in different areas including environment, medicine, healthcare, agriculture and industries. The present review aims to study the biochemistry and biosynthesis of biosurfactants exhibiting varying biomolecular structures which are produced by different microbial sources. It also provides details on roles played by biosurfactants in nature as well as their potential applications in various sectors. Basic biomolecule content of all the biosurfactants studied showed presence of carbohydrates, aminoacids, lipids and fattyacids. The data presented here would help in designing, synthesis and application of tailor-made novel biosurfactants. This would pave a way for perspectives of research on biosurfactants to overcome the existing bottlenecks in this field.

Mycelial form of dimorphic fungus Malassezia species dictates the microbial interaction.

Dandruff is one of the most common clinically manifested and studied scalp disorders. It has been associated with both bacteria and fungi. Bacteria and fungi inhabiting the scalp are known to influence each other and manifestation of dandruff. Fungal and bacterial isolates from scalp epithelial flakes (dandruff) were identified by rDNA sequencing. Local oils were tested for fungal and bacterial inhibition, interaction and biofilm formation, cell-cell interactions were studied by auto aggregation and surface thermodynamics studies. The isolates Bacillus sp.C2b1 (MK036745) and Malassezia sp. C2y1 (MK036746) were inhibited by Mahabhrungraj oil. The fungal morphological switch was evident and dependent on nutrition. Cell aggregation studies suggested the interaction of bacteria with yeast (non-pathogenic) phase of the fungus. Bacterial and yeast cells were found to be compatible for biofilm formation. The fungal mycelial surfaces were found to be conducive for interaction with both bacterial cells and yeast forms. The results here indicate the significance of mycelial phase of scalp-isolated fungus in interaction with the bacterial surfaces and also with self-yeast phase surface. This is the first report of the interaction between scalp-isolated microorganisms with respect to their surface interaction capabilities.

Characterization of Solibacillus silvestris strain AM1 that produces amyloid bioemulsifier.

Solibacillus silvestris AM1 was the first strain from the genus to be reported for the production of a functional amyloid and its potential use as a surface active agent, a thermostable glycoprotein amyloid bioemulsifier BE-AM1 capable of influencing environment and biofilm formation. Phylogenetic analysis based on 16S rRNA gene, molecular characterization studies on the basis of DNA-DNA hybridization and chemotaxonomic fatty acid methyl ester (FAME) analysis showed that S. silvestris AM1 as a strain matches with the type strain S. silvestris HR3-23. But strain AM1 differs from the type strain HR3-23 in carbon substrate utilization studies along with amyloid bioemulsifier production ability with potential industrial and environmental applications. S. silvestris AM1 exhibited bioemulsifier production at wide range of factors like pH and NaCl concentrations, while temperature influenced the bioemulsifier production indirectly (since it affected the growth). Bioemulsifier production was observed even at oligotrophic conditions (0.5 mg ml-1 ) seen usually in its native environment. In this study, we have characterized the amyloid producing S. silvestris AM1 taxonomically and also analyzed 16S rDNA of 103 sequences of Solibacillus sp. available, which indicated the possibility of new species in this genus and can be studied for industrially and environmentally important biomolecules.

Effective remediation of fish processing waste using mixed culture biofilms capable of simultaneous nitrification and denitrification.

Fish processing waste water causes pollution and eutrophication of water bodies when released untreated. Use of bacteria capable of simultaneous nitrification and denitrification (SND) as biofilms on carriers in a moving bed bioreactor (MBBR) is a popular approach but seldom used for fish processing waste water remediation. Here, we studied the variations in biofilm formation and application activities by isolates Lysinibacillus sp. HT13, Alcaligenes sp. HT15 and Proteus sp. HT37 previously reported by us. While HT13 and HT15 formed significantly higher biofilms in polystyrene microtitre plates than on carriers, HT37 exhibited highest on carriers. A consortium of the three selected bacteria grown as biofilm on MBBR carriers exhibited better remediation of ammonia (200-600 ppm and 50 mM) than the individual isolates on carriers. The mixed biofilm set on the carriers was used for nitrogenous waste removal from fish processing waste water in 2 and 20 L setups. The total nitrogen estimated by elemental analysis showed complete remediation from 250 ppm in both 2 and 20 L waste water systems within 48 h. The usual toxic nitrogenous components-ammonia, nitrite and nitrate were also remediated efficiently.

Simultaneous nitrification and denitrification by novel heterotrophs in remediation of fish processing effluent.

Three isolates viz. Lysinibacillus sp. HT13, Alcaligenes sp. HT15 and Proteus sp. HT37 isolated from fish processing effluent and having a C/N ratio of 2, removed 218, 169, and 400 µg cell(-1) day(-1) NH4(+)-N, respectively without subsequent build up of nitrite or nitrate. Ability of the selected isolates in removing NH4(+)-N, NO2(-)-N, and NO3(-)-N was checked in the presence of four commonly reported and tested effluent carbon sources viz. pyruvate, glycerol, methanol, and acetate. Further, when supplemented to fish processing wastewater containing 234 ppm total Kjeldahl's nitrogen, Lysinibacillus sp. HT13, Alcaligenes sp. HT15, and Proteus sp. HT37 could remediate 95.74, 86.17, and 76.6% nitrogen, respectively in 48 h. This is the first report of a Lysinibacillus sp. carrying out aerobically the process of simultaneous nitrification and denitrification. The results demonstrate the potential of the isolates for use in treatment of fish processing effluents and demonstrating the efficient removal of ammonia.