Chemically characterised Artemisia nilagirica (Clarke) Pamp. essential oil as a safe plant-based preservative and shelf-life enhancer of millets against fungal and aflatoxin contamination and lipid peroxidation

Abstract

The study recommends the Artemisia nilagirica (Clarke) Pamp. essential oil (ANEO) as plant-based shelf-life enhancer of millets against fungal, aflatoxin B₁ (AFB₁) contamination and lipid peroxidation with favourable safety profile. Chemical characterisation of ANEO through GC-MS, recorded 1,5-heptadiene-4-one,3,3,6-trimethyl (32.72%)as the main compound, followed by Artemisia alcohol (13.40%), alpha lonone (4.55%), benzene, methyl (1-methylethyl) (2.97%) and 1-cyclohexene-1-carboxaldehyde,4-(1-methylethyenyl) (2.23%). The mycoflora analysis of millet samples showed Aspergillus flavus strain[LHP(R)-5] as the most AFB₁ secreting strain. The ANEO inhibited growth and AFB₁ production by the toxigenic strain at 1.4 and 1.0?µL?mL^?1, respectively, and also possess broad fungitoxic spectrum. The decrement in membrane ergosterol content, enhanced leakage of cellular Ca²⁺, K⁺ and Mg²⁺ ions along with SEM and TEM study of ANEO-treated cell denotes plasma membrane as antifungal site of action. The ANEO also showed strong antioxidant activity as determined by DPPH^? and ABTS^?+ assays having IC₅₀ value 2.51 and 1.07?µL?mL^?1, respectively. More than 70.78% protection of Ragi samples from fungal contamination was observed during in situ trial. The ANEO showed favourable safety profile with high LD₅₀ value (7528.10?µL?kg^?1) for male mice and also exhibited non-phytotoxicity for Ragi seeds germination.     

Swift production of rhamnolipid biosurfactant,biopolymer and synthesis of biosurfactant-wrapped silver nanoparticles and its enhanced oil recovery

Microbial enhanced oil recovery (MEOR) is a kind of enhanced oil recovery (EOR) development, often used as a tertiary stage where oil recovery is no longer possible utilizing primary and secondary conventional techniques. Among a few potential natural operators valuable for MEOR, biosurfactants, biopolymers and biosurfactant based nanoparticles assume key jobs. Biosurfactant which are produced by microorganisms’ act as are surface active agents that can be used as an alternative to chemically synthesized surfactants. Pseudomonas aeruginosa TEN01, a gram-negative bacterium isolated from the petroleum industry is a potential biosurfactant (Rhamnolipid) producer using cassava waste as the substrate. This work focuses on production and characterization of rhamnolipid from P. aeruginosa TEN01 and its use in enhanced oil recovery. The effectiveness of Chitosan that is deacetylated form of chitin which is a biopolymer that provides density and viscosity to the fluids is not known in enhanced oil recovery yet and so it is studied. Moreover, the fabrication of biosurfactant-mediated silver nanocrystals and its application in enhanced oil recovery is also studied. Sand-Pack column was constructed and the mechanism of oil recovery in the column was studied. While incubating the crude oil containing sand packed column with Biosurfactant-biopolymer and brine flooding in the ratio of 1:2, and Biosurfactant incubation - flooding with 3 g/l of biopolymer was found to be 34.28% and 44.5% respectively. The biosurfactant based silver nanoparticles are non-toxic and have better stability when compared to chemically synthesized silver nanoparticles. The oil recovery percentage by chemical based Ag NPs and biosurfactant based Ag NPs are 14.94% and 14.28% respectively.     

Ultra‐high α‐linolenic acid accumulating developmental defective embryo was rescued by lysophosphatidic acid acyltransferase 2

For decades, genetic engineering approaches to produce unusual fatty acids (UFAs) in crops has reached a bottleneck, including reduced seed oil production and seed vigor. Currently, plant models in the field of research are primarily used to investigate defects in oil production and seedling development, while the role of UFAs in embryonic developmental defects remains unknown. In this study, we developed a transgenic Arabidopsis plant model, in which the embryo exhibits severely wrinkled appearance owing to α‐linolenic acid (ALA) accumulation. RNA‐sequencing analysis in the defective embryo suggested that brassinosteroid synthesis, FA synthesis and photosynthesis were inhibited, while FA degradation, endoplasmic reticulum stress and oxidative stress were activated. Lipidomics analysis showed that ultra‐accumulated ALA is released from phosphatidylcholine as a free FA in cells, inducing severe endoplasmic reticulum and oxidative stress. Furthermore, we identified that overexpression of lysophosphatidic acid acyltransferase 2 rescued the defective phenotype. In the rescue line, the pool capacity of the Kennedy pathway was increased, and the esterification of ALA indirectly to triacylglycerol was enhanced to avoid stress. This study provides a plant model that aids in understanding the molecular mechanism of embryonic developmental defects and generates strategies to produce higher levels of UFAs.     

两种精油熏蒸处理对金针菇贮藏品质的影响

为了开发高效的食用菌绿色保鲜剂,以新鲜的白色金针菇为供试材料,以花椒精油和丁香精油为供试熏蒸剂,分别在常温（25±1）℃和低温（4±1）℃条件下开展了适用于金针菇保鲜的精油种类和浓度的筛选试验,并对金针菇贮藏期内的感官评价、失重率、呼吸强度、褐变度、多酚氧化酶（PPO）活性、苯丙氨酸解氨酶（PAL）活性、丙二醛（MDA）以及总酚含量进行了测定。结果显示,常温（25±1）℃条件下用0.1 mL·kg-1花椒精油和0.5 mL·kg-1丁香精油保鲜效果优于其他处理,且有统计学意义（P<0.05）,0.1 mL·kg-1花椒精油和0.5 mL·kg-1丁香精油处理组感官评分分别高于对照组23.4%和27.8%,二者均能够抑制金针菇褐变、减轻腐败变质,且有统计学意义（P<0.05）;在低温（4±1）℃贮藏试验中发现,0.1 mL·kg-1花椒精油和0.5 mL·kg-1丁香精油均能有效抑制呼吸强度和PPO活性的升高（P<0.05）,其呼吸高峰较对照组分别降低了28.3%和39.6%;贮藏15 d后,精油处理组PPO活性较对照组分别降低了8.2%和16.6%;精油处理有效降低了MDA含量的产生,保持着较高的总酚含量、减轻腐烂褐变的程度。第15天时,对照组MDA含量为1.75 μmol·g-1,而花椒精油和丁香精油处理组MDA含量分别比对照组低0.15、0.40 μmol·g-1,丁香精油处理组显著低于花椒精油处理组和对照组（P<0.05）。研究结果表明,0.1 mL·kg-1花椒精油和0.5 mL·kg-1丁香精油均对金针菇采后贮藏保鲜效果显著,其中,0.5 mL·kg-1丁香精油的保鲜效果最明显,在15d的贮藏期内,金针菇依然保持着良好的品质,而对照组已经轻微褐变,部分开始腐烂。研究结果为花椒精油和丁香精油应用于金针菇采后贮藏保鲜提供了理论依据。     

Single-cell oil production by Mortierella isabellina DSM 1414 using different sugars as carbon source

Pure carbon sources, especially carbohydrates which are raw materials deriving from agro-industrial processes, are often used for small-scale single-cell oil production by fermentation. The aim of this study was to investigate the effects of different pure carbon sources on cell growth, lipid accumulation, and γ-linolenic acid (GLA) production by the filamentous fungus Mortierella isabellina DSM 1414 (Deutsche Sammlung von Mikroorganismen). The sugars utilized in this study are found extensively and abundantly in nature, especially in food raw materials and, in consequence, in agro-food industry wastes or surpluses. Thus, the potential of many waste materials containing these sugars to be used in the production of single-cell oil by fermentation could also be evaluated. The effects of the sugars utilized on cell growth, biomass production, and lipid production were investigated. Fatty acids were also analysed in the lipids produced at the end of the fermentations. Results showed that the maximum biomass production was 10.80 g/L in lactose-based media, while the maximum oil production was 5.44 g/L in maltose-based media. Oleic (20.42%–42.94%), palmitic (14.96%–22.19%), and stearic (9.00%–26.92%) acids were the major fatty acids along with linoleic acid (11.35%–18.67%) and GLA (3.56%–8.04%). The production of GLA as the target fatty acid was remarkable. This study indicates that agro-industrial waste including most of the sugars utilized (except for arabinose and sucrose with lipid production of 0.81 and 0.28 g/L, respectively) can be employed for production of single-cell oil by M. isabellina DSM 1414 which contains a high amount of GLA.     

Optimization of factors influencing enzyme activity and product selectivity and the role of proton transfer in the catalytic mechanism of patchoulol synthase

The patchoulol synthase (PTS) from Pogostemon cablin is a versatile sesquiterpene synthase and produces more than 20 valuable sesquiterpenes by conversion of the natural substrate farnesyl pyrophosphate (FPP). PTS has the potential to be used as a biocatalyst for the production of valuable sesquiterpenes such as (−)-patchoulol. The objective of the present study is to develop an efficient biotransformation and to characterize the biocatalytic mechanism of the PTS in detail. For this purpose, soluble PTS was prepared using an optimized cultivation protocol and continuous downstream process with a purity of 98%. The PTS biotransformation was then optimized regarding buffer composition, pH-value, and temperature for biotransformation as well as functional and kinetic properties to improve productivity. For the bioconversion of FPP, the highest enzyme activity was reached with the 2-(N-morphlino)ethanesulfonic acid (MES) buffer containing 10% (v/v) glycerol and 10 mM MgCl₂ at pH 6.4 and 34°C. The PTS showed an unusual substrate inhibition for sesquiterpene synthases indicating an intermediate sesquiterpene formed in the active center. Deuteration experiments were used to gain further insights into the biocatalytic mechanism described in literature. Thus it could be shown that a second substrate binding site must be responsible for substrate inhibition and that further protonation and deprotonation steps are involved in the reaction mechanism.     

Diversity in capsule and seed morphological and phytochemical features and essential oil composition of korarima (Aframomum corrorima (braun) P. C. M. jansen) collections from Ethiopia

Korarima (Aframomum corrorima (Braun) P. C. M. Jansen) is one of the Ethiopian native perennial aromatic herbs belonging to the family Zingiberaceae. Conservation of genotypes and genetic improvement of korarima has been hampered due to lack of evidences on genetic diversity of korarima. Genetic diversity of 44 korarima collections was assessed based on joint capsules and seeds morphological and phytochemical characters. Chemical composition of essential oil in seed samples has also been investigated. Physical measurements were done manually while total organic nutrients, crude fiber and total ash in the seeds were done in terms of proximate analysis. Essential oil in the seed samples was extracted by hydro-distillation and its chemical composition was analyzed with gas chromatography and mass spectrometry (GC-MS). ANOVA revealed significant variations in all the variables considered except capsule and seed shape. Ayda collections showed the largest record for fresh capsule weight (25.3 g), dry capsule weight (6.6 g), hundred seed weight (2.8 g), seed to husk ratio (2.1), total organic matter (66.6%) and seed essential oil (7.3%). Collection from Bazet was also excellent in dry weight of seed per capsule (4.45 g) while those from Metser were best in fruit husk essential oil (1.45%). Cluster analysis of the 44 collections revealed four groups each showing large (23.82–280.13) and significant (p < 0.01) pairwise genetic distance. The pattern of grouping is weak and does not match with the region of collections indicating the presence of different genetic background within the collections as well as genetic similarity among the collections. Principal component analysis (PCA) revealed about 81.2% of the total variations in the first four PCs and the pattern of grouping is similar to cluster analysis. In Essential oil composition, Bona Kike collection was remarkable in 1, 8-Cineole (60.81%). Ayda collection showed the highest m-Mentha-1,8-diene, (+)- (10.05%) and β-farnesene (24.03%). Adele Bise collection was highest in D-Limonene (20.21%). The genetic variability in essential oil composition among the samples was revealed because of spatial separation. The result suggests the potential of Ethiopian korarima in general and the collections in particular for further improvement and commercialization. Overall, the higher extent of morphological and biochemical genetic diversity observed signpost the high opportunity for genetic improvement of the crop via hybridization and selection.     

Chemical Composition and Antioxidant,Antiparasitic, Cytotoxicity and Antimicrobial Potential of the Algerian Limonium Oleifolium Mill. Essential Oil and Organic Extracts

This work aimed to investigate, for the first time, the chemical composition, antioxidant, antiparasitic, cytotoxicity, and antimicrobial activities of the aromatic plant Limonium oleifolium Mill. essential oil (EO) and organic extracts. L. oleifolium aerial parts essential oil was analyzed by GC-FID and GC-MS, and 46 constituents representing 98.25±1.12 % of the oil were identified. γ-Muurolene (10.81±0.07 %), cis-caryophyllene (7.71±0.06 %), o-cymene (7.07±0.01 %) and α-copaene (5.02±0.05 %) were the essential oil main compounds. The antioxidant activity of L. oleifolium EO and organic extracts (MeOH, CHCl₃, AcOEt, BuOH) was explored using 2,2-diphenyl-1-picrylhydrazyl (DPPH), ABTS, β-carotene/linoleic acid, cupric reducing antioxidant capacity (CUPRAC), and ferric reducing power assays. The results showed that L. oleifolium EO exhibit antioxidant capacity (IC₅₀=17.40±1.32 μg/mL for DPPH assay, IC₅₀=29.82±1.08 μg/mL for β-carotene assay, IC₅₀=25.23±1.01 μg/mL for ABTS assay, IC₅₀=9.11±0.08 μg/mL for CUPRAC assay and IC₅₀=19.41±2.06 mg/mL for reducing power assay). Additionally, the EO showed significant activity against trophozoite form of Acanthamoeba castellanii (IC₅₀=7.48±0.41 μg/mL) and promastigote form of Leishmania amazonensis (IC₅₀=19.36±1.06 μg/mL) and low cytotoxicity on murine macrophages (LC₅₀ 90.23±1.09 μg/mL), as well as good antimicrobial activity against Staphylococcus aureus, Escherichia coli, Klebsiella oxytoca, and Pseudomonas aeruginosa. These results suggest that L. oleifolium essential oil is a valuable source of bioactive compounds presenting antioxidant, antiparasitic, and antimicrobial activities. Furthermore, it is considered nontoxic.