Moderate halophilic bacteria thrive in saline conditions and produce biosurfactant (BS) which facilitates the oil scavenging activity in the oil polluted surroundings. Production of such unusual bioactive molecules plays a vital role for their survival in an extreme and adverse environment. Current research deals with isolation of Planococcus maritimus strain SAMP MCC 3013 from Indian Arabian coastline sea water for BS production. The bacterium tolerated up to 2.7 M NaCl demonstrating osmotic stress bearable physiological systems. We used integrated approach to explore the genomic insight of the strain SAMP and displayed the presence of gene for BS biosynthesis. The genome analysis revealed this potential to be intrinsic to the strain. Preliminary screening techniques viz., surface tension (SFT), drop collapse (DC) and oil displacement (OD) showed SAMP MCC 3013 as a potent BS producer. BS reduced SFT of phosphate buffer saline (PBS) pH: 7.0 from 72 to 30 mN/m with a critical micelle concentration (CMC) value of 1.3 mg/mL. Subsequent investigation on chemical characterization, using thin layer chromatography (TLC), Fourier transform infrared spectroscopy (FT-IR), nuclear magnetic resonance ( 1 H NMR and 13 C NMR) and liquid chromatography mass spectrometry (LC-MS) revealed terpene containing BS having sugar, lipid moieties. The genomic sequence analysis of P. maritimus SAMP showed complete genes in the pathway for the synthesis of terpenoid. Probably terpenoid is the accountable backbone molecule for the BS production, but the later stages of terpenoid conversion to the BS could not be found. Moreover, it is important to highlight that till today; no single report documents the in-detailed physico-chemical characterization of BS from Planococcus sp. Based on genomic and functional properties, the term terpene containing BS is denoted for the surfactant produced by P. maritimus .

The marine environment represents a well-off and diverse group of microbes, which offers an enormous natural bioactive compounds of commercial importance. These natural products have expanded rigorous awareness due to their widespread stability and functionality under harsh environmental conditions. The genus Planococcus is a halophilic bacterium known for the production of diverse secondary metabolites such as 2-acetamido-2-deoxy-α-d-glucopyranosyl-(1, 2)-β-d-fructofuranose exhibiting stabilizing effect and methyl glucosyl-3,4-dehydro-apo-8-lycopenoate displaying antioxidant activity. The genus Planococcus is reported generally for hydrocarbon degradation in comparison with biosurfactant/bioemulsifier secretion. Although Planococcus was proposed in 1894, it seized long stretch (till 1970) to get accommodated under the genus Planococcus authentically. Large-scale biosurfactant production from Planococcus was reported in 2014 with partial characterization. For the first time in 2019, we documented genomic and functional analysis of Planococcus sp. along with the physico-chemical properties of its biosurfactant. In 2020, again we screened biosurfactant for pharmacological applications. The present review discusses the comprehensive genomic insights and physical properties of Planococcusderived biosurfactant. Moreover, we also highlight the prospects and challenges in biosurfactant production from Planococcus sp. Among ∼102 reports on biosurfactant produced by marine bacteria, 43 were of glycolipid and 59 were non-glycolipid type. Under other biosurfactant type, they were identified as lipopeptide (20) like surfactin (5), glycolipoprotein/lipoprotein (12), and other non-glycolipid (22). Planococcus sp. generally produces glycolipid-type biosurfactant (4) and exopolysaccharides (2). The single report documented in the literature is on biosurfactant production (glycolipid +non glycolipid) by diverse marine microbes (39) suggesting their novelty and diversity for biosurfactant secretion.

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Phytopathogens pose severe implications in the quantity and quality of food production by instigating several diseases. Biocontrol strategies comprising the application of biomaterials have offered endless opportunities for sustainable agriculture. We explored multifarious potentials of rhamnolipid-BS (RH-BS: commercial), fungal chitosan (FCH), and FCH-derived nanoparticles (FCHNPs). The high-quality FCH was extracted from Cunninghamella echinulata NCIM 691 followed by the synthesis of FCHNPs. Both, FCH and FCHNPs were characterized by UV-visible spectroscopy, DLS, zeta potential, FTIR, SEM, and Nanoparticle Tracking Analysis (NTA). The commercial chitosan (CH) and synthesized chitosan nanoparticles (CHNPs) were used along with test compounds (FCH and FCHNPs). SEM analysis revealed the spherical shape of the nanomaterials (CHNPs and FCHNPs). NTA provided high-resolution visual validation of particle size distribution for CHNPs (256.33 ± 18.80 nm) and FCHNPs (144.33 ± 10.20 nm). The antibacterial and antifungal assays conducted for RH-BS, FCH, and FCHNPs were supportive to propose their efficacies against phytopathogens. The lower MIC of RH-BS (256 μg/ml) was observed than that of FCH and FCHNPs (>1,024 μg/ml) against Xanthomonas campestris NCIM 5028, whereas a combination study of RH-BS with FCHNPs showed a reduction in MIC up to 128 and 4 μg/ml, respectively, indicating their synergistic activity. The other combination of RH-BS with FCH resulted in an additive effect reducing MIC up to 128 and 256 μg/ml, respectively. Microdilution plate assay conducted for three test compounds demonstrated inhibition of fungi, FI: Fusarium moniliforme ITCC 191, FII: Fusarium moniliforme ITCC 4432, and FIII: Fusarium graminearum ITCC 5334 (at 0.015% and 0.020% concentration). Furthermore, potency of test compounds performed through the in vitro model (poisoned food technique) displayed dose-dependent (0.005%, 0.010%, 0.015%, and 0.020% w/v) antifungal activity. Moreover, RH-BS and FCHNPs inhibited spore germination (61–90%) of the same fungi. Our efforts toward utilizing the combination of RH-BS with FCHNPs are significant to develop eco-friendly, low cytotoxic formulations in future.

Prodigiosin a multifaceted secondary metabolite produced by Serratia spp. having great potential as a pharmaceutical. In the present study we demonstrate that oxalate supplementation in peptone glycerol production media increased organoleptic characters and yield of prodigiosin pigment extracted from oxalotrophic Serratia marcescens OX_R isolated from Indian bat guano sample. The pigment was demonstrated in-vitro as an antibacterial agent against common opportunistic skin surface pathogen Staphylococcus aureus NCIM 5021 strain as killing activity by agar well diffusion method. The docking analysis and pharmacophore modelling indicated that the probable mechanism of action of the prodigiosin was against Staphylococcus aureus DNA gyrase protein. The pigment was also found to efficiently dye both cotton and latex polymer. In summary, we describe here an oxalotrophic Serratia marcescens which may serve as a potent and economical resource of prodigiosin which owing to its dyeing and anti-bacterial activities finds future avenues to be developed as dressing material for nosocomial subjects or burn victim patients.

Bacillus aquimaris strain SAMM, a biosurfactant producing moderately halophilic marine bacterium was isolated from Indian Arabian coastline sea water. The strain was found to tolerate up to 2.7 M NaCl indicating osmotic stress sustainable physiological systems. We report here the draft genome sequence of B. aquimaris SAMM, as a candidate bacterium for bioactive surfactant producer. The whole genome sequence with 161 scaffolds, 4,414,932 bp and 44.8% of G+C content for SAMM was obtained using Illumina MiSeq sequencing technology. Annotation was added by the PGAP and RAST prokaryotic genome annotation service and shown 4,247 coding sequences, 123 RNAs genes, classified in 453 subsystems. Several genes encoding enzymatic activities against the high molecular weight polysaccharides, osmotic stress response and siderophore synthesis of potential biotechnological importance were identified in the genome.

The biosynthesis of silver nanoparticles (AgNPs) has become more significant in the recent years owing to its applications in catalysis, imaging, drug delivery, nano-device fabrication and in medicine. We propose the synthesis of silver nanoparticles from the plant extract of Syzygium cumini and evaluation of its antibacterial and chemocatalytic potential. Synthesis of AgNPs carried out by using aqueous silver nitrate. The UV–Vis absorption spectrum of the synthesized AgNPs showed a broad absorption peak at 470 nm. TEM analysis shows the morphology of AgNPs as a hexagonal matrix with average particle size is about 50 nm. XRD analysis displays the crystalline structure of AgNPs. The presence of elemental silver was confirmed with EDX analysis. FTIR analysis shows that amide groups present in proteins are dominant reducing agents and play an important role in the bioreduction of Ag+ ions to Ag0. The bioreduced AgNPs demonstrated significant catalytic properties in a reduction reaction of 4-nitrophenol to 4-aminophenol using NaBH4 in an aqueous condition. The biosynthesized AgNPs have potent antibacterial activity against common clinical pathogens. Considering the remarkable antibacterial activity against common pathogenic microorganisms, AgNPs can be used in the pharmaceutical industries.

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