Purification, Identification and Characterization of Antioxidant Peptides from Corn Silk Tryptic Hydrolysate: An Integrated In Vitro-In Silico Approach.

Corn silk (CS) is an agro-by-product from corn cultivation. It is used in folk medicines in some countries, besides being commercialized as health-promoting supplements and beverages. Unlike CS-derived natural products, their bioactive peptides, particularly antioxidant peptides, are understudied. This study aimed to purify, identify and characterize antioxidant peptides from trypsin-hydrolyzed CS proteins. Purification was accomplished by membrane ultrafiltration, gel filtration chromatography, and strong-cation-exchange solid-phase extraction, guided by 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt radical cation (ABTS•+) scavenging, hydrogen peroxide scavenging, and lipid peroxidation inhibition assays. De novo sequencing identified 29 peptides (6-14 residues; 633-1518 Da). The peptides consisted of 33-86% hydrophobic and 10-67% basic residues. Molecular docking found MCFHHHFHK, VHFNKGKKR, and PVVWAAKR having the strongest affinity (-4.7 to -4.8 kcal/mol) to ABTS•+, via hydrogen bonds and hydrophobic interactions. Potential cellular mechanisms of the peptides were supported by their interactions with modulators of intracellular oxidant status: Kelch-like ECH-associated protein 1, myeloperoxidase, and xanthine oxidase. NDGPSR (Asn-Asp-Gly-Pro-Ser-Arg), the most promising peptide, showed stable binding to all three cellular targets, besides exhibiting low toxicity, low allergenicity, and cell-penetrating potential. Overall, CS peptides have potential application as natural antioxidant additives and functional food ingredients.

Histological and proteome analyses of Microbacterium foliorum-mediated decrease in arsenic toxicity in Melastoma malabathricum.

Arsenic (As) is an increasing threat across the globe, widely known as a non-threshold carcinogen, and it is reaching harmful values in several areas of the world. In this study, the effect of plant growth promoting bacteria (Microbacterium foliorum) on inorganic arsenic (Arsenate) phytoremediation by Melastoma malabathricum plants was investigated through histological analysis and proteome profiling of the M. malabathricum plants. Two-dimensional gel electrophoresis and transmission electron microscopy were used to conduct the proteome and histological analysis. When arsenic-treated cells were compared to untreated cells, substantial changes were found (1) severely altered the morphology of the cells, intensely disturbed; (2) the cell wall was thicker; (3) drastically changed the cytoplasm, the cells were polygonal in shape, different in size (scattered), and relatively dense. Compared to the control group, the ultra-structure of the root cells of the control group revealed intact cytoplasm, vacuole, and cell wall under exposure to As + bacteria that had a minor effect on the cell form. To further understand As + bacteria interaction, proteome profiling of the root cell was analyzed. The As-induced oxidative stress enrichment was confirmed by the up-regulation of tubulin, nucleoside diphosphate kinase, and major allergen during As + bacteria exposure It was observed that the profusion of proteins involved in defence, protein biogenesis, signaling, photosynthesis, nucleoside and energy metabolism was greater in As + bacteria as compared to the rooting out of As only. Overall, it can be obviously seen that the current study demonstrates the effectiveness of phytoremediation by M. foliorum on proteins involved and responsive pathways in dealing with As toxicity in M. malabathricum plant.

Genome sequence of an uncharted halophilic bacterium Robertkochia marina with deciphering its phosphate-solubilizing ability.

The wide use of whole-genome sequencing approach in the modern genomic era has opened a great opportunity to reveal the prospective applications of halophilic bacteria. Robertkochia marina CC-AMO-30DT is one of the halophilic bacteria that was previously taxonomically identified without any inspection on its biotechnological potential from a genomic aspect. In this study, we present the whole-genome sequence of R. marina and demonstrated the ability of this bacterium in solubilizing phosphate by producing phosphatase. The genome of R. marina has 3.57 Mbp and contains 3107 predicted genes, from which 3044 are protein coding, 52 are non-coding RNAs, and 11 are pseudogenes. Several phosphatases such as alkaline phosphatases and pyrophosphatases were mined from the genome. Further genomic study (phylogenetics, sequence analysis, and functional mechanism) and experimental data suggested that the alkaline phosphatase produced by R. marina could potentially be utilized in promoting plant growth, particularly for plants on saline-based agricultural land.

Genome analysis of cellulose and hemicellulose degrading Micromonospora sp. CP22.

In this study, a bacterial strain CP22 with ability to produce cellulase, xylanase and mannanase was isolated from the oil palm compost. Based on the 16S rRNA gene analysis, the strain was affiliated to genus Micromonospora. To further investigate genes that are related to cellulose and hemicellulose degradation, the genome of strain CP22 was sequenced, annotated and analyzed. The de novo assembled genome of strain CP22 featured a size of 5,856,203 bp with G + C content of 70.84%. Detailed genome analysis on lignocellulose degradation revealed a total of 60 genes consisting of 47 glycoside hydrolase domains and 16 carbohydrate esterase domains predicted to be involved in cellulolytic and hemicellulolytic deconstruction. Particularly, 20 genes encode for cellulases (8 endoglucanases, 3 exoglucanases and 9 ß-glucosidases) and 40 genes encode for hemicellulases (15 endo-1,4-ß-xylanase, 3 ß-xylosidase, 3 α-arabinofuranosidase, 10 acetyl xylan esterase, 6 polysaccharide deacetylase, 1 ß-mannanase, 1 ß-mannosidase and 1 α-galactosidase). Thirty-two genes encoding carbohydrate-binding modules (CBM) from six different families (CBM2, CBM4, CBM6, CBM9, CBM13 and CBM22) were present in the genome of strain CP22. These CBMs were found in 27 cellulolytic and hemicellulolytic genes, indicating their potential role in enhancing the substrate-binding capability of the enzymes. CBM2 and CBM13 are the major CBMs present in cellulases and hemicellulases (xylanases and mannanases), respectively. Moreover, a GH10 xylanase was found to contain 3 CBMs (1 CBM9 and 2 CBM22) and these CBMs were reported to bind specifically to xylan. This genome-based analysis could facilitate the exploration of this strain for lignocellulosic biomass degradation.

Purification and identification of novel cytotoxic oligopeptides from soft coral Sarcophyton glaucum.

Globally, peptide-based anticancer therapies have drawn much attention. Marine organisms are a reservoir of anticancer peptides that await discovery. In this study, we aimed to identify cytotoxic oligopeptides from Sarcophyton glaucum. Peptides were purified from among the S. glaucum hydrolysates produced by alcalase, chymotrypsin, papain, and trypsin, guided by a methylthiazolyldiphenyl-tetrazolium bromide (MTT) assay on the human cervical cancer (HeLa) cell line for cytotoxicity evaluation. Purification techniques adopted were membrane ultrafiltration, gel filtration chromatography, solid phase extraction (SPE), and reversed-phase high-performance liquid chromatography (RP-HPLC). Purified peptides were identified by de novo peptide sequencing. From papain hydrolysate, three peptide sequences were identified: AGAPGG, AERQ, and RDTQ (428.45, 502.53, and 518.53 Da, respectively). Peptides synthesized from these sequences exhibited cytotoxicity on HeLa cells with median effect concentration (EC50) values of 8.6, 4.9, and 5.6 mmol/L, respectively, up to 5.8-fold stronger than the anticancer drug 5-fluorouracil. When tested at their respective EC50, AGAPGG, AERQ, and RDTQ showed only 16%, 25%, and 11% cytotoxicity to non-cancerous Hek293 cells, respectively. In conclusion, AERQ, AGAPGG, and RDTQ are promising candidates for future development as peptide-based anticancer drugs.

Development of Novel Protocol to Al3+ Stress Tolerance at Germination Stage in Indica Rice through Statistical Approaches.

Rice production is decreasing by abiotic stresses like heavy metals. In such circumstances, producing food for growing human population is a challenge for plant breeders. Excess of Al3+ in soil has become threat for high yield of rice. Improvement of crop is one of potential solution for high production. The aim of this study was to develop the new method for optimization of Al3+ toxicity tolerance in indica rice at germination stag using two-way ANOVA and Duncan's multiple-range test (DMRT). Seeds of two indica rice cultivars (Pokkali and Pak Basmati) were exposed in different concentrations (control, 5 mM, 15 mM, and 20 mM) of Al3+ toxicity at pH 4 ±0.2 for two weeks. Germination traits such as final germination percentage (FG%), germination energy (GE), germination speed (GS), germination index (GI), mean time of germination (MGT), germination value (GV), germination velocity (GVe), peak value of germination (GPV), and germination capacity (GC) and growth traits such as root length (RL), shoot length (SL), total dry biomass (TDB), and germination vigour index (GVI) were measured. To obtain the maximum number of significance (≤ 0.01%) parameters in each concentration of Al3+ toxicity with control, two-way ANOVA was established and comparison of mean was done using DMRT. The results showed that 5 mM, 10 mM, and 15 mM have less significant effects on the above-mentioned parameters. However, 20 mM concentration of Al3+ produced significant effects (≤ 0.01%). Therefore, 20 mM of Al3+ is considered optimized limit for indica cultivars (Pokkali and Pak Basmati).