Extraction of chitosan from biologically-derived chitin by bacterial chitin deacetylase: Process optimization and product quality assessment.

Commercial chitosan manufacturing process relies on strong chemical treatment on chitin that generates chitosan with undesirable properties and leads to environmental pollution. To overcome the adverse consequences, enzymatic chitosan preparation from chitin was undertaken in the current study. A potent chitin deacetylase (CDA) producing bacterial strain was screened and subsequently identified as Alcaligens faecalis CS4. After optimization 40.69 U/mL of CDA production was achieved. By treating the organically extracted chitin with partially purified CDA chitosan yield of 19.04 % was attained having 71 % solubility, 74.9 % degree of deacetylation, 21.16 % crystallinity index, 246.4 kDa molecular weight and 298 °C highest-decomposition temperature. FTIR and XRD analysis revealed characteristics peaks respectively within 870-3425 cm-1 wavenumber and 10°-20°, for enzymatically and chemically extracted (commercial) chitosan that endorses their structural similarity which validated through electron microscopic study. At 10 mg/mL chitosan concentration 65.49 % DPPH radical scavenging activity endorsed its antioxidant potential. Minimum inhibitory concentration of chitosan was 0.675, 1.75, 0.33 and 0.75 mg/mL for Streptococcus mutans, Enterococcus faecalis, Escherichia coli and Vibrio sp., respectively. Mucoadhesiveness and cholesterol binding properties were also exhibited by extracted chitosan. The present study opens a new vista for eco-friendly extraction of chitosan from chitin that is proficient and sustainable in environmental perspective.

Statistical heart rate variability analysis for healthy person: Influence of gender and body posture.

Short-term ECG-derived heart rate variability can assess autonomic function non-invasively. The purpose of this study is to investigate the influence of body posture and gender on parasympathetic-sympathetic balance by utilising electrocardiogram (ECG). A total of sixty participants including thirty males (95% CI: 23.34-26.32 years old) and thirty females (95% CI: 23.33-26.07 years old) voluntarily executed three sets of 5-min ECG recordings in supine, sitting and standing posture. A nonparametric Friedman test followed by Bonferroni post-hoc test was carried out to find the statistical differences between the group. A significant difference was observed for RR mean, low frequency (LF), high frequency (HF), ratio LF/HF and the ratio long term variability to short term variability (SD2/SD1) for p < 0.01 while respiration rate (Resp Rate), standard deviation of heart rate (STD_HR), long term variability (SD2), approximate entropy (ApEn), correlation dimension (CD) are non-significant (p > 0.01) for supine, sitting and standing. HRV indices such as standard deviation of NN (SDNN), HRV triangular index (HRVi), and triangular interpolation of NN interval (TINN) are statistically not significant for males but there are significant differences for females at a significance level 1%. Relative reliability and relatedness were evaluated through the interclass coefficient (ICC) and spearman correlation coefficient. The experimental results advocate that there is a posture-specific difference in HRV indices while the correlational studies suggest no such significant differences.

Production of glutathione from probiotic Bacillus amyloliquefaciens KMH10 using banana peel extract.

Glutathione, a tri-peptide (glutamate-cysteine-glycine) with the thiol group (-SH), is most efficient antioxidative agent in eukaryotic cells. The present study aimed to isolate an efficient probiotic bacterium having the potential to produce glutathione. The isolated strain Bacillus amyloliquefaciens KMH10 showed antioxidative activity (77.7 ± 2.56) and several other essential probiotic attributes. Banana peel, a waste of banana fruit, is chiefly composed of hemicellulose with various minerals and amino acids. A consortium of lignocellulolytic enzyme was used for the saccharifying banana peel to produce 65.71 g/L sugar to support the optimal glutathione production of 181 ± 4.56 mg/L; i.e., 1.6 folds higher than the control. So, the studied probiotic bacteria could be an effective resource for glutathione; therefore, the stain could be used as natural therapeutics for the prevention/treatment of different inflammation-related gastric ailments and as an effective producer of glutathione using valorized banana waste that has excellent industrial relevance.

Efficient valorization of feather waste by Bacillus cereus IIPK35 for concomitant production of antioxidant keratin hydrolysate and milk-clotting metallo-serine keratinase.

Keratinase production by Bacillus cereus IIPK35 was investigated under solid-state fermentation (SSF) and the maximum titer of 648.28 U/gds was revealed. Feather hydrolysates obtained from SSF exhibited paramount antioxidant properties in ABTS [2,2'-azinobis-(3-ethylbenzothiazoline)-6-sulfonic acid], FRAP [Ferric ion reducing antioxidant power], and DPPH [2,2,-Diphenyl-1-picrylhydrazyl] assay. The keratinase was purified up to homogeneity have a molecular weight of 42 kDa, and showed its stability between pH 6.5-10.0 and temperature 35-60 °C with optimum enzyme activity at pH 9.0 and 55 °C. The catalytic indices viz. Km of 9.8 mg/ml and Vmax of 307.7 µmol/min for keratin were determined. Besides keratin, the enzyme displayed broad and proteolytic activity towards other proteinaceous substrates such as casein, skim milk, gelatin, and bovine serum albumin. Pure keratinase activity was stimulated in presence of Ca2+ and Mg2+ ions, while it was strongly inhibited by both iodoacetamide and EDTA, indicating it to be a metallo-serine protease in nature. Circular dichroism study endorses the structural stability of the secondary structure at the said range of pH and temperature. The IIPK35 keratinase is non-cytotoxic in nature, shows remarkable storage stability and is stable in presence of Tween 80, Triton X 100, and sodium sulfite. Furthermore, it showed excellent milk clotting potential (107.6 Soxhlet Unit), suggesting its usefulness as an alternative milk clotting agent in the dairy industry. This study unlocks a new gateway for keratinase investigation in SSF using chicken feathers as substrate and biochemical and biophysical characterization of keratinase for better understanding and implication in industrial applications.

Structure and optical properties of twist-bend nematic liquid crystals doped with chiral dopants.

Twist-bend nematic liquid crystals (N_{TB} LCs), although consisting of achiral molecules, possess a spontaneous conic helix. They have been intensively studied and utilized in many applications in recent years. Herein we add chiral molecules to N_{TB} LCs and study their effects on the structure of the conic helix. We observe that the system is in the regular chiral nematic phase at high temperature and is still in the twist-bend nematic phase at low temperature. The addition of the chiral molecules does not induce a twist of the conic helical axis. The main effect of the chiral molecules is increasing the cone angle of the conic helix. We show that the structural chirality parameters in the chiral nematic phase and the twist-bend chiral nematic phase can be calculated from the same intrinsic chirality parameter, which only depends on the molecular structure and concentrations of the chiral molecule. We also observe a pretransitional phenomenon that the helical pitch of the chiral nematic phase increases dramatically when temperature is decreased toward the chiral nematic to twist-bend nematic phase transition temperature.

Application of Phytochemicals To Combat Fungal Pathogens of Pulses: An Approach toward Inhibition of Fungal Propagation and Invasin Activity.

The present study represented an innovative strategy for inactivating the secreted invasins (lignocellulolytic enzymes) of fungal phytopathogens using natural phytochemicals to combat fungal infection to the pulses. A fungal pathogen (Aspergillus niger SKP1) was isolated from the white lentil (Vigna mungo), which has the ability to synthesize different lignocellulolytic enzymes. An in silico docking study elucidated that quercetin, naringin, epigallocatechin gallate, curcumin, and cinnamic acid were the prime efficient phytochemicals to inhibit the activity of fungal invasive enzymes like endoglucanase, endo-1,4-ß-xylanase, and glucoamylase. Considering this observation, extracted phytochemicals in different mixtures were applied to prevent growth of the isolated pathogen under in situ experimental studies. The minimal inhibitory concentrations (MIC50) and minimal fungicidal concentration (MFC50) values of the first mixture (naringenin, epicatechin gallate, and cinnamic acid) and second mixture (quercetin and curcumin) were 170 and 220 mg/L and 320 and 380 mg/L, respectively. The studied phytochemicals were established to be cytosafe when compared to the commercial fungicides. The seeds of the white lentil were subjected to 1 year of long-term storage with the two aforementioned combinatorial phytochemicals. Subsequent morphological and physiological analyses revealed the complete protection of the stored seeds from the fungal infection. The present work has enough potentiality for the storage of pulses using natural preservatives that circumvent the adverse effect of the chemical preservatives on the ecosystem.

Antiobesity, Antihyperglycemic, and Antidepressive Potentiality of Rice Fermented Food Through Modulation of Intestinal Microbiota.

The present study has been aimed at evaluating the antiobesity, antihyperglycemic, and antidepressive potentials of Asparagus racemosus starter-based rice fermented foods. High-throughput NGS technology has revealed a number of bacterial genera in the prepared fermented rice, such as Lactobacillus (29.44%), Brevundimonas (16.21%), Stenotrophomonas (6.18%), Pseudomonas (3.11%), Bacillus (2.88%), and others (<2%). Eight-week administration of rice fermented food has increased food intake, whole-body weight, organ weight, different fat masses, serum lipid profiles, and histology of liver and adipose tissues in HFD-induced obese mice. In addition, upregulation of fatty acid oxidation and downregulation of adipocytogenesis- and lypogenesis-related genes along with the expression of their regulatory nuclear factors such as PPARα, PPARγ, PPARδ, and SREBP-1c have also been noted. Moreover, fermented food decreases fasting blood glucose level and improves glucose and insulin tolerance as well as the expression of GLUT4 receptor. Antiobesity and antihyperglycemic effects are also supported by the changes in insulin, leptin, and adiponectin hormone levels. The real-time polymerase chain reaction (RT-PCR) and denaturing gradient gel electrophoresis (DGGE) analyses have clearly demonstrated the intense colonization of Bacteroides, Lactobacillus, and Bifidobacterium, as well as the suppressed growth rate of γ- and δ-Proteobacteria and Firmicutes in the gut after fermented food intake. In the intestine, the latter group of microorganisms possibly modulate short-chain fatty acid (SCFA) levels such as acetate, butyrate, and propionate more than twofold. The impairment of memory-learning and anxiety-like obesity-associated cognitive phenotypes is mitigated significantly (p < 0.01) by fermented food as well. Thus, the formulated fermented food could be used as a natural therapeutic to alleviate obesity and its associated psychological and pathophysiological ailments.

Biodeinking of waste papers using combinatorial fungal enzymes and subsequent production of butanol from effluent.

The present study aimed to enzymatic deinking of waste papers and to valorize the effluent for biobutanol production. Application of fungal enzymatic cocktail (cellulase, amylase, xylanase, pectinase, lipase, and ligninase) on office used paper, newspaper, and ballpen written paper leading to improvement in brightness (84.91, 72.51, 76.69 % ISO), InKd (82.89, 68.95, 76.49%), κ-number (12.9, 13.6, and 13.1), opacity (27.91, 30.07, and 2.85%), tensile strength (49.24, 45.31, and 46.98 Nm/g), respectively and indices were consistent with chemical treated pulps. The quality of effluent generated during enzymatic deinking in respect to BOD and COD level was eco-friendlier than the chemical process. The enzyme-treated effluent was employed as supporting substrate for butanol (18.4 g/l) production by Clostridium acetobutylicum ATCC824. Material balance and life cycle assessment of the whole processes were evaluated to validate its industrial and environmental relevance.

Saccharification of lignocellulosic biomass using an enzymatic cocktail of fungal origin and successive production of butanol by Clostridium acetobutylicum.

A multistep approach was undertaken for biobutanol production targeting valorization of agricultural waste. Optimum production of lignocellulolytic enzymes [CMCase (3822.93U/mg), FPase (3640.93U/mg), ß-glucosidase (3873.92U/mg), xylanase (3460.24U/mg), pectinase (3359.57U/mg), α-amylase (4136.54U/mg), and laccase (3863.16U/mg)] was accomplished through solid-substrate fermentation of pretreated mixed substrates (wheat bran, sugarcane bagasse and orange peel) by Aspergillus niger SKN1 and Trametes hirsuta SKH1. Partially purified enzyme cocktail was employed for saccharification of the said substrate mixture into fermentable sugar (69.23 g/L, product yield of 24% w/w). The recovered sugar with vegetable extract supplements was found as robust fermentable medium that supported 16.51 g/L biobutanol production by Clostridium acetobutylicum ATCC824. The sequential bioprocessing of low-priced substrates and exploitation of vegetable extract as growth factor for microbial butanol production will open a new vista in biofuel research.

Preparation of rice fermented food using root of Asparagus racemosus as herbal starter and assessment of its nutrient profile.

The popularity of traditional fermented food products is based on their healthiness. The addition of a starter brings consistent, desirable, and predictable food changes with improved nutritive, functional, and sensory qualities. The addition of a mixture of plant residues as a starter or source of microbes is an age-old practice to prepare traditional fermented food and beverages, and most of the reported data on traditional foods were based on the analysis of the final product. The contribution of an individual starter component (plant residue) is not experimentally substantiated for any traditional fermented food, but this data are very essential for the formulation of an effective starter. In this study, Asparagus racemosus, which used as a common ingredient of starter for preparation of rice fermented food in the Indian sub-continent, was used as a starter for the preparation of rice fermented food under laboratory scale, and its microbial and nutrient profile was evaluated. The fermented product was a good source of lactic acid bacteria, Bifidobacterium sp., yeast, etc. The food product was acidic and enriched with lactic acid and acetic acid with titratable acidity of 0.65%. The content of protein, fat, minerals, and vitamins (water-soluble) was considerably improved. Most notably, oligosaccharide (G3-matotriose), unsaturated fatty acids (ω3, ω6, ω7, and ω9), and a pool of essential and non-essential amino acids were enriched in the newly formulated food. Thus, the herbal starter-based rice fermented food would provide important macro- and micronutrients. They could also deliver large numbers of active microorganisms for the sustainability of health. Therefore, the selected plant part conferred its suitability as an effective starter for the preparation of healthier rice-based food products.

Tailoring in fungi for next generation cellulase production with special reference to CRISPR/CAS system.

Cellulose is the utmost plenteous source of biopolymer in our earth, and fungi are the most efficient and ubiquitous organism in degrading the cellulosic biomass by synthesizing cellulases. Tailoring through genetic manipulation has played a substantial role in constructing novel fungal strains towards improved cellulase production of desired traits. However, the traditional methods of genetic manipulation of fungi are time-consuming and tedious. With the availability of the full-genome sequences of several industrially relevant filamentous fungi, CRISPR-CAS (clustered regularly interspaced short palindromic repeats/CRISPR-associated protein) technology has come into the focus for the proficient development of manipulated strains of filamentous fungi. This review summarizes the mode of action of cellulases, transcription level regulation for cellulase expression, various traditional strategies of genetic manipulation with CRISPR-CAS technology to develop modified fungal strains for a preferred level of cellulase production, and the futuristic trend in this arena of research.

Extraction of chitin from Litopenaeus vannamei shell and its subsequent characterization: an approach of waste valorization through microbial bioprocessing.

Chemical extraction of chitin is very hazardous and costly which can be overwhelmed by microbial bioprocessing. In this study, potent protease and lactic acid-producing bacteria were screened and identified as Alcaligens faecalis S3 and Bacillus coagulans L2, respectively. Productions of protease and lactic acid by the respective bacterial strains were optimized. The shell of Litopenaeus vannamei was sequentially treated with the partially purified protease and lactic acid and the treatment conditions were optimized for betterment of chitin yield. Spectral characterization by SEM-EDS, IR, XRD, NMR, XPS and thermal characterization by TG and DTG analysis of the extracted chitin was made and compared with commercial one. It was revealed that both the chitin have similar characteristics. Therefore, it can be articulated that chitin can be extracted from crustacean shells in pure form by microbial bioprocessing which will be a good catch for biorefinary industries for chitin extraction through greener route.

Microbial decomposition of crustacean shell for production of bioactive metabolites and study of its fertilizing potential.

Crustacean shell waste disposal is considered as biggest problem in seafood processing centers. Incineration and landfilling are the commonest ways of disposal of the waste which causes environmental pollution. Microbial bio-conversion is one of the promising approaches to minimize the wastes by utilizing the same for deriving different value added metabolites. In this perspective, chitinase- and protease-producing bacterial strains were isolated from shrimp culture pond, and the potent isolate was subsequently identified as Alcaligenes faecalis SK10. Fermentative optimization of the production of chitinase (85.42 U/ml), protease (58.57 U/ml), and their catalytic products, viz., N-acetylamino sugar (84 µg/ml) and free amino acids (112 µg/ml), were carried out by utilizing shrimp and crab shell powder as principal substrate. The fermented hydrolysate (FH) was subsequently applied to evaluate its potential to be a candidate fertilizer for the growth of leguminous plant Pisum sativum and Cicer arietinum, and the results were compared with chitin, chitosan, and commercial biofertilizer amended group. The results revealed that FH have paramount potential to improve plants morpho-physiological parameters like stem and root length, chlorophyll, cellular RNA, protein content, and soil physico-chemical parameters like total nitrogen, magnesium, calcium, phosphorus, and potassium significantly (p < 0.05). Moreover, the application of FH also selectively encouraged the growth of free-living nitrogen-fixing bacteria, Rhizobium, phosphate-solubilizing bacteria in the soil by 4.82- and 5.27-, 5.57- and 4.71, and 7.64- and 6.92-fold, respectively, in the rhizosphere of P. sativum and C. arietinum, which collectively is a good sign for an ideal biofertilizer. Co-supplementation of FH with commercial PGPR-biofertilizer significantly influenced the morpho-physiological attributes of plant and physico-chemical and microbial attributes of soil. The study validated proficient and sustainable utilization of fermented hydrolysate of waste crustacean shell as biofertilizer.

Evaluation of nutrient profile, biochemical composition and anti-gastric ulcer potentialities of khambir, a leavened flat bread.

Khambir is a leavened staple food among the native highlanders of Western Himalaya. It is prepared by sourdough fermentation of wheat flour with yeast (YAK) or buttermilk (BAK). Both types of bread were rich in carbohydrate, protein, dietary fiber, containing less fat and gluten, and enriched with lactic acid, vitamins, and minerals. The in vitro digestibility test showed a slow glucose-controlled release potential of khambir that reflected improved content of rapidly digestible starch, slowly digestible starch, resistant starch, and predicted glycemic index. The changes of crystallinity to amorphous structures of starch, content of protein and fatty acid, and accumulation of 17 major metabolites were evaluated through FTIR and GC-MS. The extracts of khambir alleviated cold-induced gastric ulcers in the animal model as it exhibited histoprotective and anti-inflammatory activities. This study demonstrated that the traditional leavened bread khambir is nutritious and can alleviate gastric lesions related to acute mountain sickness.

Generalized phase compensator of continuous time plants.

This work proposes a novel design method for generalized order lead/lag compensators. With respect to the traditional lead/lag compensator, it introduces a new parameter, ß, which is a non-integer number. A new design method of the compensator is introduced in order to quantify its design parameters. Compared to its integer order counterpart, the generalized order lead compensator facilitates with the unique solution of desired design specifications with maximum phase at the desired gain cross-over frequency to achieve reshaping of the loop frequency domain characteristics. On the other hand, generalized order lag compensator is designed so as to allow minimum phase lag at the new gain crossover frequency. Examples with simulation and real-time results are presented to validate the efficacy of the proposed approach.

Assessment of Likelihood Ratio for Four Contact Dermatitis Symptoms of Vinca Minor.

BACKGROUND: Contact dermatitis (CD) is a frequently occurring medical condition, for which Vinca minor (VM) is one of the recommended homeopathic medicines. However, the symptoms indicating this medicine have not yet been assessed systematically. Likelihood ratio (LR), based on Bayesian statistics, may yield better estimation of a medicine's indication than the existing method of entry of symptoms into materia medica and repertories. METHODS: We investigated LRs of four CD symptoms of VM: (1) great sensitiveness of skin, with redness and soreness from slightest rubbing; (2) weeping eczema with foul, thick crusts; (3) itching amelioration in open air; and (4) CD of scalp. An observational, prospective, patient-outcome study was conducted in five different practice settings on 390 CD patients over 18 months using three outcomes-Glasgow Homeopathic Hospital Outcome Scale (GHHOS), Scoring Atopic Dermatitis (SCORAD), and Dermatology Life Quality Index (DLQI), assessed at baseline, after 3 and 6 months. The LR of each of the four symptoms was estimated as per the patient-rated outcomes on GHHOS. RESULTS: Seventy-four VM and 316 non-VM cases were analyzed. Estimated LRs were as follows: symptom 1, 1.29 (95% confidence interval [CI]: 0.65 to 2.60); symptom 2, 1.48 (95% CI: 0.80 to 2.74); symptom 3, 1.70 (95% CI: 0.94 to 3.07); symptom 4, 1.36 (95% CI: 0.74 to 2.51). There were statistically significant reductions in SCORAD and DLQI scores over 3 and 6 months. CONCLUSION: There was insufficient evidence to attribute any of the four assessed symptoms clearly to VM. Though non-significant, a high LR was observed for "itching amelioration in open air" (symptom 3). Symptoms in the homeopathic materia medica for VM are perhaps over-represented. More research of this nature is warranted.

Elucidation of structural and functional integration of a novel antimicrobial peptide from Antheraea mylitta.

We report here the amino acid sequence of an antimicrobial peptide of Antheraea mylitta (peptide fraction II) effectively killed urinary tract associated MDR E. coli (Dutta et al., 2016), as Gly-Gly-Gly-Gly-Gly-Gly-His-Leu-Val-Ala. The physicochemical and biological properties of this peptide were evaluated by computational analysis and its isoelectric point, grand average of hydropathicity and Boman index values were found to be 6.74, 0.42 and -1.17kcal/mol, respectively. One valid model of peptide fraction II was constructed, that contains two antiparallel ß sheets with a hairpin and appeared as 'U' shaped structure. The glycine rich composition (Gly1, Gly5, Gly6 and Ala10) facilitates mostly for its flexibility or dynamicity, and in its other wing, aggregation prone residues (Leu8, Val9, Ala10) triggered its auto-aggregations when contacted only with the microbial membrane. We employed simulation of peptide binding on the membrane, showed stable and deep insertion of peptide fraction II into the membrane through its hydrophobic tail (up to 3.3±1.46Å). Molecular docking study with Patchdock server revealed that this peptide could interact with the lipid aliphatic chain of 1-palmitoyl-2-oleoyl-phosphoethanolamine (POPE) bilayer and may linked to membrane distortion as we have reported earlier. Further, the studied peptide has been predicted not to exhibit any antigenicity and non-responsive to RBC membrane. These data for the first time provide new insights of an antimicrobial peptide from silkworm A. mylitta and it may serve as the template for the design of novel peptide antibiotics from this group of insect against MDR Gram-negative bacteria.

Multi-Response Optimization of Granaticinic Acid Production by Endophytic Streptomyces thermoviolaceus NT1, Using Response Surface Methodology.

Streptomyces thermoviolaceus NT1, an endophytic isolate, was studied for optimization of granaticinic acid production. It is an antimicrobial metabolite active against even drug resistant bacteria. Different media, optimum glucose concentration, initial media pH, incubation temperature, incubation period, and inoculum size were among the selected parameters optimized in the one-variable-at-a-time (OVAT) approach, where glucose concentration, pH, and temperature were found to play a critical role in antibiotic production by this strain. Finally, the Box-Behnken experimental design (BBD) was employed with three key factors (selected after OVAT studies) for response surface methodological (RSM) analysis of this optimization study.RSM analysis revealed a multifactorial combination; glucose 0.38%, pH 7.02, and temperature 36.53 °C as the optimum conditions for maximum antimicrobial yield. Experimental verification of model analysis led to 3.30-fold (61.35 mg/L as compared to 18.64 mg/L produced in un-optimized condition) enhanced granaticinic acid production in ISP2 medium with 5% inoculum and a suitable incubation period of 10 days. So, the conjugated optimization study for maximum antibiotic production from Streptomyces thermoviolaceus NT1 was found to result in significantly higher yield, which might be exploited in industrial applications.

Alteration of Zeta potential and membrane permeability in bacteria: a study with cationic agents.

In the present study, we have tried to establish the correlation between changes in Zeta potential with that of cell surface permeability using bacteria (Escherichia coli and Staphylococcus aureus). An effort has been made to establish Zeta potential as a possible marker for the assessment of membrane damage, with a scope for predicting alteration of cell viability. Cationic agents like, cetyl trimethyl ammonium bromide and polymyxin B were used for inducing alteration of Zeta potential, and the changes occurring in the membrane permeability were studied. In addition, assessment of poly-dispersity index (PDI), cell viability along with confocal microscopic analysis were performed. Based on our results, it can be suggested that alteration of Zeta potential may be correlated to the enhancement of membrane permeability and PDI, and it was observed that beyond a critical point, it leads to cell death (both Gram-positive and Gram-negative bacteria). The present findings can not only be used for studying membrane active molecules but also for understanding the surface potential versus permeability relationship.

Enzymatic hydrolyzed feather peptide, a welcoming drug for multiple-antibiotic-resistant Staphylococcus aureus: structural analysis and characterization.

This study aimed to explore the bactericidal activity of a feather-degraded active peptide against multiple-antibiotic-resistant (MAR) Staphylococcus aureus. An antibacterial peptide (ABP) was isolated from the chicken feathers containing fermented media of Paenibacillus woosongensis TKB2, a keratinolytic soil isolate. It was purified by HPLC, and its mass was found to be 4666.87 Da using matrix-assisted laser desorption ionization time-of-flight (MALDI-TOF) spectroscopy. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) values of this peptide were 22.5 and 90 µg/ml, respectively. SEM study revealed the distorted cell wall of the test strain along with pore formation. The possible reason for bactericidal activity of the peptide is due to generation of reactive oxygen species (ROS), resulting in membrane damage and leakage of intracellular protein. Complete sequence of the peptide was predicted and retrieved from the sequence database of chicken feather keratin after in silico trypsin digestion using ExPASy tools. Further, net charge, hydrophobicity (77.7 %) and molecular modelling of the peptide were evaluated for better understanding of its mode of action. The hydrophobic region (17 to 27) of the peptide may facilitate for initial attachment on the bacterial membrane. The ABP exhibited no adverse effects on RBC membrane and HT-29 human cell line. This cytosafe peptide can be exploited as an effective therapeutic agent to combat Staphylococcal infections.