Yeast Extract Research Articles

Aerobic bacteria induced biomineralization: effects of nutrient and calcium content on the nanostructure and chemical composition of simulated cement mixture

During the past two decades, aerobic bacteria induced biomineralization has gained popularity for autonomous sealing of cracks in concrete structures due to its environmentally friendly characteristics of carbon retention. However, the mechanism of the biomineralization induced by aerobic bacteria for concrete crack sealing is still unclear due to the complex chemistry of cement matrix. Also, as the main nutrient for bacterial growth, the effect of yeast extract (YE) on biomineralization should be properly evaluated. For the first time, this study investigates the effects of YE and calcium content on the development of nanostructure and chemical composition of cement matrix during the biomineralization process induced by aerobic bacteria Bacillus cohnii. The effects of calcium content were realized by constructing a simulated cement mixture consisting of calcium hydroxide and synthesised C-S-H with different C/S ratios. The effects of YE content were evaluated by the addition of different amounts of YE into simulated cement mixture with different C/S ratios. Results suggest that 10 g/l of YE can cause a high pH value of 10 and an unsuccessful growth of bacteria in simulated cement mixture with C/S ratios 0.6 and 0.8. Upon increasing the YE from 10 g/l to 20 g/l, the pH reduced from 10 to 9 and the bacteria was successfully grown. Higher amounts of bicarbonate ions can cause an enhanced decalcification of synthesised C-S-H rather than calcium hydroxide. The aerobic bacteria Bacillus cohnii showed superior performance on calcium absorption and calcite precipitation, being a promising way for practical concrete crack sealing.

Exploring the impact of selenium-enriched peptides from yeast autolysate on dough properties: Insights into mechanisms from gluten perspectives

This study investigated the impact of Selenium (Se)-enriched yeast autolytic peptides (SeYAP) with different Se levels on dough properties as well as the related mechanism by focusing on gluten. SeYAP prolonged the dough's development time by up to 131 % and stability time by up to 28 %. It also decreased dough's viscoelasticity and rendered dough softer. Additionally, SeYAP diminished the binding capacity of dough to water and augmented the fluidity of water. Protein composition, disulfide bonds and fluorescence spectroscopy revealed that SeYAP could induce depolymerization of glutenin aggregate through sulfhydryl/disulfide bond exchange and hydrophobic interactions. Seven Se-enriched peptides were identified from the fraction with strong ability to depolymerize gluten. Specifically, six peptides contained selenocysteine, while another peptide contained selenomethionine. Molecular docking indicated that Se-enriched peptides could interact with amino acids (such as glutamine, tyrosine and proline) in gluten via hydrophobic interactions and/or hydrogen bonds.

Biodegradation and high-value utilization of waste cooking oil: Strategies and mechanisms for producing lipopeptide biosurfactants using Bacillus subtilis YZQ-2

This study explored the strategies and mechanisms of Bacillus subtilis YZQ-2 in producing lipopeptide biosurfactants using waste cooking oil (WCO) as a raw material. The optimal conditions achieved a WCO utilization rate of 75.88% and a biosurfactant yield of 0.30g/L at pH 6.0, 30°C, with 20g/L WCO and 5g/L yeast extract. GC-MS analysis of degradation products at different intervals elucidated the mechanism of WCO degradation. After 72hours of fermentation, a reduction in linoleic and palmitic acid levels indicated the completion of lipid hydrolysis and the continuation of β-oxidation. The biosurfactants, identified as lipopeptides (surfactin and fengycin), exhibited stability in alkaline environments (pH 7.0-11.0) and high-salt concentration (5-45g/L). Genomic and transcriptomic analyses of Bacillus subtilis YZQ-2 revealed genes associated with biosurfactant production, which were upregulated in the presence of WCO. The differential expression values (log2 fold change) were SrfAA 3.30, SrfAB 3.31, SrfAC 3.63, FenA 2.42, FenB 2.55, FenC 1.99, FenD 2.03 and FenE 2.29, respectively. The proposed biosynthesis pathway of lipopeptides begins with the hydrolysis of WCO by lipase into glycerol and fatty acids. The glycerol is then transformed into pyruvate through glycolysis, entering the Tricarboxylic Acid cycle. Additionally, pyruvate contributes to synthesizing amino acids and branched-chain fatty acids, which serve as precursors for lipopeptide synthesis. These findings underscore the potential of WCO as a sustainable feedstock for biosurfactant production.

Optimization of Fermentation Conditions of Cordyceps militaris and In Silico Analysis of Antifungal Property of Cordycepin Against Plant Pathogens.

Cordyceps militaris, a medicinal fungus, has gained considerable attention owing to its potential health benefits, notably the production of bioactive compounds such as cordycepin. Cordycepin possesses significant antifungal, antibacterial, and antiviral properties. The present study focused on optimizing the fermentation conditions for C.militaris to boost the production of mycelia and cordycepin, alongside investigating its antifungal properties using in silico and in vitro approaches. The optimal conditions, yielding the highest cordycepin and mycelial biomass, were a temperature of 20°C and a pH range of 4-6, with glucose and sucrose as carbon sources and yeast extract and casein hydrolysate as nitrogen sources. Under these conditions, cordycepin production peaked at low pH (600-1000 mg/L) and with carbon and maltose (400-500 mg/L). The low temperature favored cordycepin production (400 mg/L), whereas casein hydrolysate as a nitrogen source boosted cordycepin yield (600 mg/L). The docking analysis indicated that cordycepin had the highest binding affinity for the tubulin beta chain 2 (-10.4 kcal/mol) compared to the fungicide tebuconazole (-7.9 kcal/mol for both targets). The in silico results were corroborated by in vitro studies, where the mycelial extract of C.militaris inhibited approximately 75% of fungal growth at a concentration of 6000 ppm. These findings suggest that optimizing fermentation conditions significantly enhances cordycepin production, and cordycepin shows antifungal solid activity, making it a promising agent for biocontrol in agriculture.

Fidelibacter multiformis gen. nov., sp. nov., isolated from a deep subsurface aquifer and proposal of Fidelibacterota phyl. nov., formerly called Marine Group A, SAR406 or Candidatus Marinimicrobia.

A Gram-negative, obligatory anaerobic, chemoheterotrophic bacterium, designated strain IA91T, was isolated from sediments and formation water from deep aquifers in Japan. IA91T derives its peptidoglycan, energy and carbon from exogenous cell wall fragments, namely muropeptides, released from actively reproducing bacteria, and is dependent on other bacteria for cell wall formation, growth and even cell shape: IA91T is irregular rod-shaped but coccoids when muropeptide is absent. IA91T grew in a temperature range of 25-45 °C with optimum growth at 40 °C. IA91T utilized limited substrates, yeast extract, muropeptides and d-lactate. The major end products from yeast extract degradation were acetate, hydrogen and carbon dioxide. Co-cultivation with a hydrogen-scavenging methanogenic archaeon promoted IA91T growth. No anaerobic respiration with nitrate, nitrite, sulphate or Fe(III) was observed. The major cellular fatty acids are C16 : 0, C18 : 1 trans9, C18 : 0 and C17 : 0. The G+C content of the genomic DNA was 45.6 mol%. Phylogenetic analysis based on 16S rRNA gene and conserved protein sequences involved in replication, transcription and translation indicated that IA91T belonged to the candidate phylum Marine Group A (MG-A, SAR406 or Ca. Marinimicrobia) with no cultivated representatives. Based on the phenotypic and phylogenomic characteristics, a new genus and species, Fidelibacter multiformis gen. nov., sp. nov., is proposed for IA91T (= JCM 39387T = KCTC 25736T). In addition, a new bacterial phylum named Fidelibacterota phyl. nov. is proposed for the candidate phylum MG-A represented by F. multiformis and Fidelibacteraceae fam. nov., Fidelibacterales ord. nov. and Fidelibacteria classis nov.

Identification and characterisation of dextran produced by a novel high yielding Weissella cibaria Fiplydextran strain

An exopolysaccharide (EPS)-producing bacterial strain was isolated from fermented soy milk and identified as Weissella cibaria strain Fiplydextran through morphological, biochemical and 16S rDNA sequence analysis. Here, we report the optimisation of cultural conditions for the organism to achieve maximum EPS production, along with its molecular characterisation, functional properties, and prebiotic potential. The exceptionally high EPS yield (0.61 g per g of sucrose) was obtained from the optimised medium (200 g/L of sucrose, 15 g/L of yeast extract) at 30 °C after 48 h. HPAEC-PAD analysis revealed that the EPS is homopolymer of glucose having Mw as 3.23 × 107 Da determined using viscosity method. Methylation analysis and NMR results confirmed the EPS as dextran with α (1 → 6)-linkage (96.5 %) as main chain and α (1 → 3)- as branch chain linkage (3.5 %). Thermogravimetric analysis exhibited higher thermal stability of EPS. The EPS was observed to support the growth of Bacteroides spp. in pure culture form but not that of Lactobacillus or Bifidobacterium spp. However, a low level of bifidogenic activity was observed upon use of mixed culture of B. fragilis and B. longum. The research implies industrial applications of W. cibaria Fiplydextran for the production of high molecular weight dextran with better yield.

Application of neural network in prediction of acetic acid yield by Acetobacters

In the present work, artificial neural network (ANN) is applied for the estimation of acetic acid yield for 3 different species of Acetobacters like, Acetobacter pasteurianus (NCIM 2104), Acetobacter aceti (NCIM 2116) and Acetobacter xylinum (NCIM 2526). Though there is open literature mentioning acetic acid and ANN can be found, they hardly describe the usage of ANN in prediction of fermentation based acetic acid production. Indeed, a deep dearth of existing literature is felt in this area to develop a robust ANN model to predict the yield of biologically obtained acetic acid and this work is a step towards bridging that research gap. The performance of the model has been estimated with R2 (0.992, 0.988 and 0.992, respectively for the mentioned microbial species) and RMSE (0.0287, 0.034 and 0.020, respectively for the same species). The most relevant operating parameters like, temperature, agitator speed, concentrations of supplemented yeast extract and tryptone, have been considered to carry out fermentation on cheese whey permeate containing fermentable lactose (48.5 g L-1) to transform into acetic acid. Outcome datasets obtained from rigorous experimental investigations performed on the direct fermentative production of acetic acid are trained in the ANN model to predict the product yield. Such machine-learning methodology encourages reasonably accurate prediction of product generation which is extremely tough to obtain through classical analytical processes.

Investigation into optimizing fermentation processes to enhance uric acid degradation by probiotics

To enhance the activity of Lactiplantibacillus plantarum FS4722 (L. plantarum FS4722) in reducing uric acid, this study optimized the culture medium components and fermentation conditions using response surface methodology. The results indicated that the optimal culture medium comprised glucose at 25.61g/L, yeast extract powder (YEP) at 26.86g/L, and nucleoside addition at 0.48g/L. The optimal fermentation conditions were: a fermentation time of 10h, an initial pH of 6.5, a fermentation temperature of 33 °C, and an inoculum size of 1.0%. Under these conditions, the nucleoside degradation ability of L. plantarum FS4722 increased by 41.9 times, enhancing its potential applications in reducing uric acid and developing anti-gout foods, health supplements, and pharmaceuticals.

Enhancement of the Production of Tropane Alkaloids in the Hyoscyamus Niger L. Callus Using Different Biotic Elicitors

This study looked at the amount of tropane alkaloids in both the leaves of the mother plant and the callus cultures of Hyoscyamus niger L. It also looked at how biotic elicitation affects the growth of callus cultures and increases the production of alkaloids. The investigation identified and quantified three primary tropane alkaloids (Hyoscyamine, Scopolamine, and Atropine) from both sources. Remarkably, the callus cultures exhibited obviously higher levels of alkaloids in comparison to the leaves of the mother plant, implying their potential as a valuable reservoir for alkaloid production. Concerning the effects of biotic elicitation, the study showed that the application of chitosan (CHT), yeast extract (YE), and fungal extract of Trichoderma asperellum yielded a substantial decrease in callus weight when contrasted with the control group. This decrease became more pronounced with escalating concentrations of the elicitors. In terms of alkaloid synthesis, a clear correlation between the concentration of bio stimulants and tropane alkaloid levels was established. Particularly, CHT elicitation displayed the most pronounced enhancement in levels of tropane alkaloids among the three elicitors. Notably, the highest CHT concentration of 40 mg/L yielded the most elevated levels of alkaloids, measuring at 25.3 µg/g for Hyoscyamine, 31.2 µg/g for Scopolamine, and 21.5 µg/g for Atropine. This represents approximate percentage increases in concentration of 208%, 183%, and 198%, respectively, when compared to the control treatment. Generally, these findings carry significant implications for advancing tropane alkaloid biosynthesis, with potential applications spanning the pharmaceutical and biotechnology sectors.

Statistical Optimization of Lipase Production by Aspergillus oryzae Using Olive Mill Wastewater

Among different sources of lipases, fungal lipases are hydrolytic enzymes owing much importance in industrial applications. However, the high production cost limits the industrial application of lipases. To address this issue, we have attempted to optimize lipase production by Aspergillus oryzae on olive mill wastewater (OMW) based medium. Media optimization is considered one of the best ways to economically produce a large quantity of lipase. The medium components were optimized by a statistical approach for optimal lipase production. The Plackett–Burman design was applied to identify the significant factors and response surface methodology to optimize medium components. The enzyme activity was highest under the following conditions: 3.49 g.L-1 glucose, 5.58 g.L-1 yeast extract and 0.72 g.L-1 CaCl2. A feasibility analysis of lipase production using the optimized data was performed, and at optimized conditions, lipase activity increased from 110.21 U.mL-1 to 212.53 U.mL-1, or an increase of 1.93 times.

Canola meal extract as a low-cost substrate in Mortierella alpina culture for the production of arachidonic acid

The demand for high-quality and cost-effective raw materials is growing across various industries. Canola meal (CM), a low-cost by-product of canola processing facilities, boasts an impressive nutritional profile comprising protein, carbohydrates, vitamins, and minerals, making it a potential candidate for microbial culture media. Saskatchewan leads globally in canola production and plans to expand its canola processing facilities. Commercial valorization of CM could not only optimize the management of this by-product but also offer additional incentives and financial returns to regional canola stakeholders. Efficient utilization of canola meal extract (CME) in producing polyunsaturated fatty acids (PUFAs), such as arachidonic acid (ARA), holds promise as valuable ingredients or base chemicals for the food, feed, and nutraceutical industries. This study focused on incorporating pH 10.5 treated alkaline extract (AE) and temperature 160°C treated subcritical extract (SE) of CM into the culture medium of Mortierella alpina, an oleaginous fungus, by replacing conventional yeast extract (YE). Trials investigated the effect of aeration levels ranging from 0.5 to 2.0 vvm and revealed that increasing oxygen supply significantly boosted fungal growth rate and ARA content in biomass up to 0.39 day⁻¹ and 21.86 %, respectively. ARA production correlated positively with biomass accumulation and lipid content. Replacing YE with CME resulted in less significant differences (P < 0.05) in biomass and lipid accumulation. Additionally, AE- and SE-supplemented media exhibited higher ARA accumulation of 144.91 mg/L and 165.8 mg/L, respectively, compared to standard media (124.87 mg/L). Therefore, this study introduces canola meal extract (CME) as a novel nitrogen source in microbial media, with comparative demonstrations showing its efficiency to be similar to that of conventional extracts.

Sustainable Exploitation of Wine Lees as Yeast Extract Supplement for Application in Food Industry and Its Effect on the Growth and Fermentative Ability of Lactiplantibacillus plantarum and Saccharomyces cerevisiae

Wine lees, the residue left behind after racking or bottling of wine, are predominantly composed of dead yeast cells, ethanol, phenolic compounds, and tartrates. Yeast extract (i.e., commercial yeast extract), a highly nutritious powder derived from commercially cultivated yeast biomass, is commonly used in nutrient media as a nitrogen source. In the context of by-product valorization, wine lees could potentially be used to produce a substitute for commercial yeast extract (CYE). In our study we investigated the growth and fermentative ability of two major winemaking microorganisms, Lactiplantibacillus plantarum and Saccharomyces cerevisiae, in culture media containing a wine lees yeast extract (WLYE) and a CYE. The effects of yeast extract type, concentration, and initial cell concentration (y0) on key kinetic parameters—maximum specific growth rate (μmax), lag phase duration (λ), and maximum cell concentration (ymax)—were evaluated. For L. plantarum, the results showed that using a WLYE led to similar kinetic parameters to those obtained with a CYE, with λ being unaffected by y0 in samples containing a WLYE. For S. cerevisiae, simultaneous addition of both yeast extracts led to increased μmax values (up to 0.136 h−1) compared to individually added yeast extracts, although this negatively affected λ and ymax. Current research on wine lees is mainly focused on using them as a substrate to produce valuable metabolites through fermentation, overlooking the potential industrial applications of the nutrient-rich autolysate. The findings of this study appear promising for the holistic valorization of wine lees, contributing towards the concepts of sustainability and circular economy.

Oral administration of cysteine peptides attenuates UV-B-induced skin erythema and pigmentation in humans

The oral administration of antioxidants may suppress UV-B-induced skin damage. HITHION YH-15, the extract of Torula yeast (Cyberlindnera jadinii), is rich in cysteine-containing peptides such as reduced and oxidized glutathione (GSH and GSSG), γ-glutamylcysteine (γ-Glu-Cys), and cysteinylglycine (Cys-Gly). These four constituents are termed cysteine peptides. In this study, we investigated the protective effects of cysteine peptides against UV-B in a randomized, placebo-controlled, double-blind, parallel-group study. A total of 90 healthy males and females aged 30–59 years were enrolled and randomized into two groups of 45 individuals each (cysteine peptides (48 mg/day) and placebo). Changes in UV-B-induced erythema and pigmentation were compared between groups after 5 weeks of test food intake. The minimal erythema dose (MED) significantly increased (*p = 0.019) in the cysteine peptides group compared to that in the placebo group, indicating suppression of UV-B-induced erythema. ΔL* value significantly increased (***p < 0.0001) in the cysteine peptides group compared to that in the placebo, indicating pigmentation suppression. We demonstrated that oral administration of cysteine peptides suppresses UV-B-induced erythema and pigmentation through multiple mechanisms. Thus, cysteine peptides may find use as nutricosmetics for maintaining skin health and well-being.UMIN Clinical Trials Registry ID: UMIN 000050157.

Effects of GSH on Alcohol Metabolism and Hangover Improvement in Humans: A Randomized Double-Blind Placebo-Controlled Crossover Clinical Trial.

The definition of alcohol hangovers refers to a combination of mental and physical side effects that occur after drinking. One of the ways that hangovers can be ameliorated is by promoting the rapid and effective elimination of acetaldehyde to alleviate the discomfort it causes. This study aimed to investigate the effects of GSH (yeast extract containing 50 mg of glutathione) on the hangover-relieving effect. A randomized double-blind placebo-controlled crossover clinical trial was conducted with 40 participants who reported experiencing hangover symptoms. Participants consumed alcohol at a rate of 0.78 g per kg body weight with 40% whiskey, adjusted according to their weight. Alcohol and acetaldehyde concentrations in serum were analyzed at 0, 0.25, 1, 2, 4, 6, and 15 h after alcohol consumption. In the GSH group, the serum alcohol concentration decreased, although this change was not statistically significant. The serum acetaldehyde concentration was significantly lower in the GSH group in comparison to the placebo group (at 0.25, 1, 4, and 6 h (p < 0.01) and at 0.5, 2, and 15 h (p < 0.001) after alcohol consumption). However, there was no significant difference between the two groups on questionnaires such as the Acute Hangover Scale and the Alcohol Hangover Severity Scale. Overall, we consider the discovery that GSH lowered acetaldehyde concentration, a crucial factor in alcohol metabolism, to be more considerable. Therefore, GSH administration effectively reduces acetaldehyde levels in serum. This result suggests that this effect may contribute to the relief of hangover symptoms.

Potato peel as substrate for Single Cell Protein in animal feed by submerged fermentation

Single-cell protein (SCP) has gained attention in scientific research as a vital source of protein in animal feed and human food. Taking into account the importance of SCP, an attempt was made in the current research to grow Rhizopus oligosporus and Saccharomyces cerevisiae biomass by selecting potato peel as a substrate. The potato peel was treated with sulfuric acid to form potato peel hydrolysate following acid hydrolysis. In 1.0-L potato peel hydrolysate, 2.5-g/L KH2PO4, 0.5-g/L MgSO4, 0.5-g/L NaCl, and 10 g/L yeast extract were taken to prepare growth media. The moisture content of potato peel was examined by following standard procedure of the Association of Official Agricultural Chemists (AOAC). The Kjeldahl method was used to determine the protein content, and glucose was examined by using the dinitrosalicylic acid (DNS) method. Optimization of SCP yield was accomplished by following the ‘one factor at a time’ method. The effect of each parameter, such as incubation period, temperature and pH on SCP production was analyzed. Bioreactor scale-up production of SCP was performed in a jar fermenter. To enhance SCP, yield co-culture of Saccharomyces cerevisiae and Rhizopus oligosporus was used in a bioreactor that yielded 19 g/L of SCP. Thus, as a nutritional supplement for living organisms, SCP can effectively fulfill protein scarcity globally.

Improved levan production by novel Calidifontibacillus erzurumensis LEV207 using one variable at a time approach.

Levan, an exopolysaccharide, has applications in the medical and food sectors. Under natural conditions, levan is produced at a low concentration by microorganisms. This current study focuses on optimizing levan production by a one-variable-at-a-time approach from a novel marine bacterium, Calidifontibacillus erzurumensis LEV207. The growth and levansucrase production by C. erzurumensis LEV207 were studied to optimize the media components and conditions. Sucrose and yeast extract proved to be a good levansucrase inducer. The pH of 6.0 and temperature of 30°C, along with MgSO4 as salt, increased the enzyme activity. Sucrose and yeast extract at the concentration of 50% and 1%, respectively, produced the maximum enzyme activity of 427.4µmol/mL/min after 48h of incubation. Sevag reagent was used for the purification of levan. The optimization process increased the levan (EPSLEV207) production sevenfold with a final yield of 65.58g/L. To confirm the structure and nature of EPSLEV207, NMR and XRD were performed, and the functional groups present in EPSLEV207 were determined using FTIR. Chemical hydrolysis of levan confirmed fructose as the monomer, making EPSLEV207 a homopolysaccharide. EPSLEV207 exhibited 49% and 22% radical scavenging activity against DPPH and ABTS radicals, respectively, and promoted the growth of probiotic strain. EPSLEV207 showed an 88% water solubility index and 78% water retention capacity. The optimization process has increased the yield of levan, highlighting the potential of C. erzurumensis LEV207 to be a viable option for industrial applications.

Co-Encapsulation of Coffee and Coffee By-Product Extracts with Probiotic Kluyveromyces lactis.

Coffee and coffee by-products contain several chemical compounds of great relevance, such as chlorogenic acid (CGA), trigonelline, and caffeine. Furthermore, yeasts have been the target of studies for their use as probiotics because of their interesting biochemical characteristics. The combined administration of probiotic microorganisms with components that provide health benefits mediated by alginate encapsulation is an alternative that ensures the stability of cells and chemical compounds. In this context, the aim of this work was to co-encapsulate the probiotic yeast Kluyveromyces lactis B10 and extracts of green coffee beans, coffee silverskin, and PVA (black, green or immature, and sour coffee beans). The bioactive composition, antioxidant and antimicrobial activities of the extracts, microcapsule morphological characteristics and encapsulation efficiency, ability of the encapsulation to protect the yeast cells subjected to gastrointestinal conditions, and antioxidant activity of the microcapsules were evaluated. All the evaluated extracts showed antioxidant activity, of which PVA showed 75.7% and 77.0%, green coffee bean showed 66.4% and 45.7%, and coffee silverskin showed 67.7% and 37.4% inhibition of DPPH and ABTS•+ radicals, respectively, and antimicrobial activity against the pathogenic bacteria E. coli, Salmonella, and S. aureus, with high activity for the PVA extract. The microcapsules presented diameters of between 1451.46 and 1581.12 μm. The encapsulation efficiencies referring to the yeast retention in the microcapsules were 98.05%, 96.51%, and 96.32% for green coffee bean, coffee silverskin, and PVA, respectively. Scanning electron microscopy (SEM) showed that the microcapsules of the three extracts presented small deformations and irregularities on the surface. The K. lactis cells encapsulated in all treatments with the extracts showed viability higher than 8.59 log CFU/mL, as recommended for probiotic food products. The addition of green coffee bean, coffee silverskin, and PVA extracts did not reduce the encapsulation efficiency of the alginate microcapsules, enabling a safe interaction between the extracts and the K. lactis cells.

Potential Nitrogen Fixing Rhizobia Isolated from Some Wild Legumes of Nagaland Based on RAPD with Nif-directed Primer and Their Biochemical Activities

Wild legumes are widely dispersed and can survive in challenging environments as bacteria dwell in their nodules and help each other. Although Nagaland is home to many wild legume varieties, research on the microbial diversity that goes along with them is still in its infancy. This work aimed to characterize several wild legume root nodules and distinguish possible rhizobial isolates using RAPD and nif-directed RPO1 primer. Nodule bacteria were isolated in Yeast extract culture media. Based on their colony morphology, 150 isolates were selected for performing RAPD with nif-directed RPO1 primer. Eighty-four isolates were bonded with RPO1 primer, and a few biochemical tests were conducted on RPO1-positive isolates. Activities that promoted plant development were also investigated for these isolates. Of all the isolates, 18 exhibited phosphate solubilization capacity, while 38 isolates were found to produce IAA. This study entails a large variety of rhizobia in the nodules, which were able to promote growth. Hence, these isolates promise to be bio-fertilizers that could improve agricultural operations.

Valorization of the solid fraction of wine lees through optimized accelerated autolysis: Effect of temperature, pH and solid concentration on free-amino acid concentration

Winemaking, as an agro-industrial process, generates substantial amounts of by-products, notably grape pomace and wine lees. The latter constitutes the residue left behind during the racking or bottling of wine, consisting mainly of dead yeast cells, ethanol, phenolic compounds, tartrates, and other compounds. Within the framework of by-products’ valorization, the rich content of dead yeast cells in wine lees render them conducive to the production of a yeast extract substitute through autolysis. In the present study, the effect of pretreatment, temperature, pH, and solid concentration on the efficiency of white wine lees autolysis was investigated. Moreover, the effect of enzyme addition and dynamic thermal protocols were investigated. Efficiency assessment was based on the increase of free α-amino nitrogen (FAN) found in the autolysate. The finding revealed a significant increase of FAN in all cases, with treated and untreated white wine lees reaching a maximum increase of 477% and 834%, respectively. Furthermore, the amino acid profile of autolysates was significantly affected by the autolysis temperature. These results hold promise for the comprehensive, holistic valorization of wine lees, suggesting their potential use as a nutrient source for microorganisms, such as wine yeast, or even as a grape must nitrogen modulator. Consequently, this by-product can be integrated back into the same industrial process from which it originates, namely winemaking. This not only aligns with the principles of circular economy but also underscores the potential for sustainable development within wineries.

Improving the medium composition for the production of the natural blue-violet pigment violacein by a new Janthinobacterium sp. isolate.

The interest in natural compounds has increased primarily due to their beneficial health and environmental aspects. However, natural sources of some compounds, such as bluish pigments, are limited, requiring the development of efficient processes to meet commercial demands. This study isolated a blue-violet bacterium from spoiled cooked rice and identified it as a potential new species of Janthinobacterium through 16S rDNA analysis. Ultra-high performance liquid chromatography-tandem mass spectrometry analyses confirmed that the blue-violet pigment violacein was responsible for the bluish color. In laboratory conditions, different carbon and nitrogen sources were evaluated in submerged culture media to enhance pigment production. Glycerol did not result in significant pigment production by this strain, as expected from previous reports. Instead, a culture medium composed of yeast extract and fructose yielded higher pigment production, reaching about 113.68±16.68 mg l-1 after 120 h. This result provides crucial insights for future studies aiming for sustainable and commercially viable violacein production. Based on a bioeconomy concept, this approach has the potential to supply natural and economic bluish pigments for various industrial sectors, including pharmaceutical, cosmetic, and food.