Fermentation Kinetics Research Articles

Investigation of fermentation profiles, bacterial community structure and bacterial β-carotene synthesis of alfalfa silage treated with propionic acid or its combination with squalene

Abstract This study examined the fermentation dynamics, bacterial community composition and bacterial β-carotene synthesis in alfalfa that was ensiled for 3, 15, 45 and 90 days without additives (CON), or with a chemical agent (propionic acid, PA); or a combination of PA and squalene, SQPA). The results showed that silage treated with PA had a lower (P < 0.01) pH value than the CON silage in the early ensiling phase (3–15 days). Meanwhile, silage treated with PA had the highest contents of lactic acid, acetic acid and PA after 90 days of ensiling (P < 0.01). The β-carotene in alfalfa was lost seriously in the initial ensiling phase (3 days) and epiphytic Pantoea agglomerans with the ability to produce β-carotene became extinct. With the extension of ensiling time, the loss of β-carotene was alleviated in all silages. PA and SQPA not only lowered bacterial diversity and simplified bacterial networks but also facilitated the emergence of new β-carotene-producing bacteria. The metabolic function prediction indicated that β-carotene synthesis tended to decrease initially and subsequently increase during ensiling. Furthermore, the variance of enzymes involved in the bacterial synthesis of β-carotene in silages was influenced by PA, SQPA and ensiling time. In summary, the impact of solely adding PA demonstrated superior effects on the fermentation quality of alfalfa silage compared to the effects observed with SQPA. Throughout the ensiling of alfalfa, the succession of different β-carotene-producing bacteria resulted in fluctuations in the levels of β-carotene.

Identification of Key Parameters Inducing Microbial Modulation during Backslopped Kombucha Fermentation.

The aim of this study was to assess the impact of production parameters on the reproducibility of kombucha fermentation over several production cycles based on backslopping. Six conditions with varying oxygen accessibility (specific interface surface) and initial acidity (through the inoculation rate) of the cultures were carried out and compared to an original kombucha consortium and a synthetic consortium assembled from yeasts and bacteria isolated from the original culture. Output parameters monitored were microbial populations, biofilm weight, key physico-chemical parameters and metabolites. Results highlighted the existence of phases in microbial dynamics as backslopping cycles progressed. The transitions between phases occurred faster for the synthetic consortium compared to the original kombucha. This led to microbial dynamics and fermentative kinetics that were reproducible over several cycles but that could also deviate and shift abruptly to different behaviors. These changes were mainly induced by an increase in the Saccharomyces cerevisiae population, associated with an intensification of sucrose hydrolysis, sugar consumption and an increase in ethanol content, without any significant acceleration in the rate of acidification. The study suggests that the reproducibility of kombucha fermentations relies on high biodiversity to slow down the modulations of microbial dynamics induced by the sustained rhythm of backslopping cycles.

Effect of Brosimum alicastrum Foliage on Intake, Kinetics of Fermentation and Passage and Microbial N Supply in Sheep Fed Megathyrsus maximus Hay.

An experiment was carried out to assess the effect of the incorporation of sun-dried foliage of Brosimum alicastrum into rations based on hay of Megathyrsus maximus on intake, rumen fermentation, kinetics of passage, microbial nitrogen supply to the small intestine, apparent digestibility in Pelibuey hair sheep. Four rations were randomly allotted to four rumen-cannulated lambs (BW = 37.4 ± 4.9 kg) using a 4 × 4 Latin square design to assess the effect of increasing levels (0, 15, 30 and 45% DM basis) of foliage of Brosimum alicastrum on a basal ration of M. maximus. Organic matter intake and water consumption increased linearly (p < 0.01) with increasing levels of B. alicastrum in the ration. The rate and potential extent of rumen fermentation of OM and CP of B. alicastrum were 10.6%/h and 86.6% and 11.4%/h and 95.2%, respectively, but no effect (p > 0.05) was found on the potential rumen degradation of DM (40.2%) or on the rate of degradation of DM (0.033%/h) of M. maximus, although a positive effect was found in the rumen degradation rate of NDF (p < 0.05). VFA and ammonia concentration in the rumen and the rate of passage of solids and liquids through the rumen (k1) increased linearly (p < 0.01) with increasing levels of B. alicastrum. Rumen pH was not affected by the incorporation of B. alicastrum (p > 0.05). Microbial nitrogen supply to the small intestine (p < 0.001), apparent digestibility of dry matter (p < 0.01) and NDF (p < 0.05) of the rations were also significantly increased as a result of the incorporation of B. alicastrum foliage. Results from this experiment suggest that the foliage of Brosimum alicastrum can be readily incorporated at around 30% of the ration of dry matter in hair sheep with beneficial effects on feed intake, rate of passage and microbial N supply to the lower tract.

Flavor profile and quality of strawberry wine are improved through sequential fermentation with indigenous non-Saccharomyces yeasts and Saccharomyces cerevisiae

In order to explore novel producing strategies for enhancing flavor compounds profile and quality of strawberry wine, we studied the effect of the sequential fermentation of two selected indigenous non-Saccharomyces yeasts (Hanseniaspora uvarum PGR9 and Kurtzmaniella quercitrusa PGT1) and Saccharomyces cerevisiae CGMCC 2.3854 on the fermentation kinetics, physicochemical characteristics, organic acids, antioxidant activity, volatile compositions, and sensory properties. Results showed that the ethanol content produced by the fermentation of Kq-Sc was significantly lower than that of Sc pure fermentation. In addition, the total volatile compounds concentration produced by the fermentation of Hu-Sc (16.2 ± 3.6 mg/L) and Kq-Sc (19.5 ± 3.1 mg/L) were significantly higher than that of Sc pure fermentation (13.8 ± 2.0 mg/L). In particular, the Kq-Sc strawberry wine presented the highest number of relative odor-active compounds (rOAV ≥1). Moreover, strawberry wine fermented by Hu+Kq-Sc showed the highest ABTS free radical scavenging ability and the highest overall sensory qualities. The results indicated that the K. quercitrusa PGT1 strain could be an alternative yeast for producing strawberry wine, and the sequential fermentations of Kq-Sc and Hu+Kq-Sc were effective strategies for improving the flavor and quality of strawberry wine.

Optimization of fermentation parameters and their impact on the final properties of the cereal-legume-based fermented product

The enhancement of food diversification through the utilization of underutilized crops is imperative at both national and household levels due to their inherent high nutritional value. Employing fermentation technology stands out as a promising approach for processing these crops at the household scale. Fermented foods exhibit attributes conducive to maintaining a healthy dietary regimen, as they are abundant in nutrients, cost-effective, easy to produce, and serve as potent sources of proteins and other essential dietary components for alleviating protein malnutrition, particularly in children. In the current study, experiments were conducted to standardise the process for formulating idli batter using blends of barnyard millet, black gram, and black soybean, employing fermentation technology. The experimental design followed the Box-Behnken approach, encompassing three levels of predicted variables: particle size (400, 500, and 600 μ), temperature (28, 32, and 36 °C), and fermentation time (8, 10, and 12 h). Various properties of the resultant idli batter influenced by fermentation parameters, including batter volume, pH, titratable acidity, and density, were meticulously examined. The observed batter volume ranged from 1 to 67 mL, pH from 5.7 to 4.58, titratable acidity from 0.36 to 0.67%, and density from 1.09 to 0.63 g/cm3. The optimal particle size of 400 μ, coupled with a fermentation temperature of 34.5 °C and a fermentation time of 12 h, yielded maximal expansion in batter volume, thereby contributing to the preparation of idli of superior quality. Additionally, the fermentation kinetics of the optimized batter were investigated to elucidate the growth patterns of microorganisms involved in the fermentation process.

Use of AirMixing M.I.® resonance waves to produce aroma richer Sangiovese wine without sulphites addition in a sustainable way

In recent years, wine without sulphite addition has grown increasingly popular. In this work, resonance waves (AirMixing M.I.®) were applied to Sangiovese must in fermentation to produce wine without sulphite addition, monitoring the fermentation kinetics and analyzing polyphenols and volatile organic compounds (VOCs) extraction. Resonance waves were created by injecting compressed air into a 10 hL stainless steel tank filled with Sangiovese must, without pumping-over/delestage, and no sulphites in all the process (AM). Control wine was produced using pumping-over/delestage and adding sulphur dioxide. After 4 months in bottles, simulating the commercial habit used to sell in spring the last year wine, volatile acidity was significantly lower in AM wine, while total anthocyanins, trans-resveratrol and free quercetin were significantly higher. Among free (VOCs), the classes of terpenes and benzenoids were significantly higher in the Control wine while the classes of aldehydes, alcohols, volatile phenols, lactones and pyrazine were in the AM wine. Unlike free VOCs, in glycosylated VOCs, terpenes and benzenoids were significantly higher in AM wine. In conclusion, resonance waves permit to speed up the fermentation increasing phenols extraction and producing wines with excellent maintenance of VOCs, requiring less energy and labor, and thus being more economically and environmentally sustainable.

Metabolomic kinetics investigation of Camellia sinensis kombucha using mass spectrometry and bioinformatics approaches

Kombucha is created through the fermentation of Camellia sinensis tea leaves, along with sucrose, utilizing a symbiotic consortium of bacteria and yeast cultures. Nonetheless, there exists a dearth of comprehensive information regarding the spectrum of metabolites that constitute this beverage. To explore this intricate system, metabolomics was used to investigate fermentation kinetics of Kombucha. For that, an experimental framework was devised to assess the impact of varying sucrose concentrations and fermentation temperatures over a ten-day period of kombucha fermentation. Following fermentation, samples were analyzed using an LC-QTOF-MS system and a distinctive metabolomic profile was observed. Principal component analysis was used to discriminate between metabolite profiles. Moreover, the identified compounds were subjected to classification using the GNPS platform. The findings underscore notable differences in compound class concentrations attributable to distinct fermentation conditions. Furthermore, distinct metabolic pathways were identified, specially some related to the biotransformation of flavonoids. This comprehensive investigation offers valuable insights into the pivotal role of SCOBY in driving metabolite production and underscores the potential bioactivity harbored within Kombucha.

In vitro gas fermentation kinetics of compounded diets containing varying levels of Tetrapleura tetraptera fruit meal

The study investigated in vitro gas fermentation kinetics of compounded diets containing different quantities of Tetrapleura tetraptera (TTFM). Three replicates of each dietary sample (200 mg) were incubated in buffered rumen liquor for 48 hours and the parameters such as in vitro dry matter digestibility (IVDMD), organic matter digestibility (OMD), short-chain fatty acids (SCFA) and methane gas (CH4) were determined using in vitro gas production technique. One-way Analysis of Variance (ANOVA) was used to analyze the gathered data. The IVDMD exhibited substantial variation (p&lt;0.05) among treatments. The diet with 1.0 % Tetrapleura tetraptera had the highest in vitro dry matter digestibility (IVDMD), which may be useful for effective feed conversion efficiency. The acetate and propionate with total volatile fatty acids raised the inclusion levels of TTFM in the rams' diet by 1.5 to 2.0 %. Tetrapleura tetraptera fruit meal can be added to ruminant diets at a rate of up to 2.0 % to increase daily weight gain, nitrogen utilization, and nutrient digestibility, resulting in better storage of energy

Mixed hay produced in Southern Italy: nutritive value and environmental impact

The aim of this study was to characterize eight mixed forages preserved as hays produced in four agricultural and livestock farms located in four Provinces (Avellino, Benevento, Campobasso, and Potenza) of Southern Italy, different for environmental condition. Nutritive value, in vitro fermentation characteristics and kinetics, including methane production were determined. The little differences observed between sampling areas highlighted that the forage produced in Avellino area is the most interesting in terms of chemical composition, nutritive value, in vitro characteristics, and environmental impact. Data obtained allow having more information about hays produced in the study area, useful for farmers to make balanced rations, to maintain animal health and guarantee high quality of production.

Changes in physicochemical and gut microbiota fermentation property induced by acetylation of polysaccharides from Cyperus esculentus

In this study, the impact of acetylation on physicochemical, digestive behavior and fermentation characteristics of Cyperus esculentus polysaccharides (CEP) was investigated. Results indicated that the acetylation led the molecules to be more likely aggregated, followed by a higher crystallinity, a lower apparent viscosity and a higher ratio of G" to G' (tan δ). Importantly, the acetylated polysaccharides (ACEP) had a lower digestibility, but its molecular weight was lower than that of original polysaccharides (CEP) following a simulated saliva-gastrointestinal digestion. Gut microbiota fermentation indicated that both polysaccharides generated outstanding short-chain fatty acids (SCFAs), in which the acetylated polysaccharides had a faster fermentation kinetics than the original one, followed by a quicker reduction of pH and a more accumulation of SCFAs, particularly butyrate. Fermentation of both polysaccharides promoted Akkermansia, followed by a reduced richness of Klebsiella. Importantly, the current study revealed that the fermentation of acetylated polysaccharides enriched Parabacteroides, while fermentation of original ones promoted Bifidobacterium, for indicating their individual fermentation characteristics and gut environmental benefits.

Optimization of the fermentative production of L-methionine by engineered Escherichia coli

As the only essential amino acid containing elemental sulphur, L-methionine has important physiological and biochemical functions in living organisms. However, the fermentative production of L-methionine has not met the requirements of industrial production because of its low production level. In this paper, the fermentation process of an efficient L-methionine producing strain E. coli W3110ΔIJAHFEBC trc-fliY trc-malY/PAM glyA-22 metF constructed previously was systematically optimized. Based on the optimal initial glucose concentration, the effects of different fed-batch fermentation processes, including DO-Stat, pH-Stat, controlling residual sugar control at different level and feeding glucose with constant rate, on L-methionine fermentation were studied. It was found that the control of glucose concentration greatly affected the fermentation process. Subsequently, an optimal fed-batch fermentation process was developed, where the L-methionine titer was increased to 31.71 g/L, the highest yield reported to date, while the fermentation time was shortened to 68 h. Meanwhile, a fermentation kinetics model under the optimal fed-batch fermentation conditions was established, which fitted well with the biosynthesis process of L-methionine. This study may facilitate further development of the fermentative production of L-methionine.

The Influence of Chitosan on the Chemical Composition of Wines Fermented with Lachancea thermotolerans.

Chitosan exerts a significant influence on various chemical parameters affecting the quality of wine produced using multiple strains of Lachancea thermotolerans. The impact of chitosan on these parameters varies depending on the specific strain studied. We observed that, under the influence of chitosan, the fermentation kinetics accelerated for all examined strains. The formation of lactic acid increased by 41% to 97% across the studied L. thermotolerans strains, depending on the specific strain. This effect also influenced acidity-related parameters such as total acidity, which increased by 28% to 60%, and pH, which experienced a decrease of over 0.5 units. The consumption of malic acid increased by 9% to 20% depending on the specific strain of L. thermotolerans. Nitrogen consumption also rose, as evidenced by all L. thermotolerans strains exhibiting a residual value of Primary Amino Nitrogen (PAN) of below the detection limit, and ammonia consumption increased by 90% to 100%, depending on the strain studied. However, certain parameters such as acetic acid, succinic acid, and glycerol showed contradictory results depending on the strain under investigation. In terms of volatile composition, chitosan supplementation led to increased production of i-butanol by 32% to 65%, 3-methylbutanol by 33% to 63%, and lactic acid ethyl ester by 58% to 91% across all studied strains of L. thermotolerans. Other analyzed aroma compounds exhibited varying changes depending on the specific strain of L. thermotolerans.

Integrating microbial abundance time series with fermentation dynamics of the rumen microbiome via mathematical modelling.

The rumen represents a dynamic microbial ecosystem where fermentation metabolites and microbial concentrations change over time in response to dietary changes. The integration of microbial genomic knowledge and dynamic modelling can enhance our system-level understanding of rumen ecosystem's function. However, such an integration between dynamic models and rumen microbiota data is lacking. The objective of this work was to integrate rumen microbiota time series determined by 16S rRNA gene amplicon sequencing into a dynamic modelling framework to link microbial data to the dynamics of the volatile fatty acids (VFA) production during fermentation. For that, we used the theory of state observers to develop a model that estimates the dynamics of VFA from the data of microbial functional proxies associated with the specific production of each VFA. We determined the microbial proxies using CowPi to infer the functional potential of the rumen microbiota and extrapolate their functional modules from KEGG (Kyoto Encyclopedia of Genes and Genomes). The approach was challenged using data from an in vitro RUSITEC experiment and from an in vivo experiment with four cows. The model performance was evaluated by the coefficient of variation of the root mean square error (CRMSE). For the in vitro case study, the mean CVRMSE were 9.8% for acetate, 14% for butyrate and 14.5% for propionate. For the in vivo case study, the mean CVRMSE were 16.4% for acetate, 15.8% for butyrate and 19.8% for propionate. The mean CVRMSE for the VFA molar fractions were 3.1% for acetate, 3.8% for butyrate and 8.9% for propionate. Ours results show the promising application of state observers integrated with microbiota time series data for predicting rumen microbial metabolism.

Effect on calf growth of accounting for early in vitro degradation kinetics when composing a calf starter ration

Degradation kinetics of concentrates were investigated in vitro and fed to calves to determine if weight gains reflected in vitro results. Five concentrate ingredients (steam dried sugar beet pulp, drum dried sugar beet pulp, toasted faba beans, untreated faba beans and soybean hulls) were fermented using the in vitro gas production technique in two 48 hour fermentations and degradation parameters were established. Two pairs of calf starter rations were formulated based on the in vitro degradation profiles of the individual concentrates and pelleted. The rations were balanced using NorFor – the Nordic feed evaluation system- to provide a similar net energy (MJ/day) but with differing in vitro degradation kinetics during the first 16 h of fermentation. Each pair consisted of rations made with concentrate ingredients that had an expected in vitro rapid (“Fast”) degradation and an expected in vitro slower (“Slow”) degradation relative to each other during the first 16 h of fermentation. The first pair (Fast_1 and Slow_1) consisted mainly of a single fast or slow in vitro degraded concentrate ingredient, either steam dried sugar beet pulp (48.5 % of dry matter) or drum dried sugar beet pulp (49.5 %), respectively. The second pair (Fast_2 and Slow_2) included two expected fast or slow in vitro degraded ingredients. The extra “Fast” concentrate ingredient, in addition to steam dried sugar beet pulp, was untreated faba beans, which brought the total fast concentrate ingredients in the Fast_2 ration to 64 % of DM. The second “Slow” concentrate ingredient was toasted faba beans, in addition to soybean hulls, which replaced the drum dried sugar beet pulp. The total “Slow” ingredients in the Slow_2 ration was 65.8 % of DM. The first pair of concentrate rations were each fed to 18 calves on a commercial dairy farm, while the second pair was fed to 59 calves each on a beef fattening station. The calves were fed for 8 weeks, and each calf was weighed weekly. The mean total weight gain of each calf after the trial was 68.5 kg and 68.6 for Fast_1 and Slow_1, respectively and 64.9 kg and 63.8 kg for Fast_2 and Slow_2, respectively. There was a tendency for Slow_1 to lead to increased growth compared to Fast_1 (P=0.052), when accounting for the initial weight of the calves, but there were no differences between Fast_2 and Slow_2. There was no significant effect on feed efficiency. The large differences in fermentation kinetics seen in the concentrate ingredients in vitro were not seen in the concentrate rations or the weight gain response of the growing calves.

Improve nutritive value of silage based on prickly pear peel by-products

Prickly pear (Opuntia ficus-indica L. Mill) is widely cultivated in arid regions of every continent for its nutritious fruits and various commercial applications, cactus pear cladodes are used as forage in the most arid regions, while recently prickly pear by-products are studied as ruminant feed. They are characterised by a high moisture and sugar content; therefore, it is necessary to study suitable conservation methods. The aim of this study was to verify the effectiveness of silage to preserve prickly pear peels (PP) in a mixture with other by-products at different inclusion levels (5% straw and 6% or 12% wheat bran). For each treatment, six under vacuum micro-silos were prepared and, after 40 d of storage, the state of preservation was evaluated. Subsequently, the aliquots were analysed for chemical composition and incubated with sheep rumen fluid to evaluate the fermentation kinetics. The use of wheat bran and straw added to PP resulted in an increase in dry matter (DM); PP silage with wheat bran was found to have higher protein content and nutritional value. The greater presence of lactic acid was found in PP, such as acetic acid, therefore the lactic/acetic ratio was 2.33, significantly lower than silages with the addition of wheat bran. Silage with 5% straw showed the lowest level of organic matter disappearance (OMD) and the cumulative volume of gas (OMCV) produced during the incubation. The PP showed the fastest fermentation rate achieved after 12 h of fermentation, while those containing wheat bran, presented a higher maximum fermentation rate (Rmax), which need longer time to be achieved. Canonical discriminant analysis (CDA) showed clear discrimination of different silages based on their chemical characteristics and parameters detected during in vitro incubation. Overall, the silages with the addition of wheat bran can be considered the best and, of the two, those produced with the addition of 12% bran. Finally, ensilage represents a conservation technique suitable for preserving the nutritional characteristics of PP.

Grapevine and Horseradish Leaves as Natural, Sustainable Additives for Improvement of the Microbial, Sensory, and Antioxidant Properties of Traditionally Fermented Low-Salt Cucumbers

The agro-food industry produces large amounts of secondary by-products, which can act as a source of bio-active ingredients. These ingredients can be used as valuable additives to support the sustainable circular economy concept. This study aimed to analyze the potential application of horseradish and grapevine leaves in the fermentation process of low-salt pickled cucumbers to improve their sensory and functional properties. The pour plate technique, RT-qPCR, HPLC, and a nine-point hedonic scale test with penalty analysis were used to analyze the traditionally fermented product. The research showed that the addition of both horseradish and grapevine leaves did not negatively affect the kinetics of fermentation and had a positive effect on the overall desirability. Moreover, they contributed to an increase in the concentration of antioxidant compounds, namely gallic acid (grape leaves) and ellagic acid (grapevine and horseradish leaves). Bacterial metabiome analysis showed the positive effect of all analyzed additives on an increase in the relative expression of genes responsible for the synthesis of selected bacteriocins (plantaricin and acidocin). Research results indicated a high potential for sustainable use of by-products (horseradish and grapevine leaves) in the production of traditional low-salt fermented cucumbers with high health-promoting potential.

A consortium of different Saccharomyces species enhances the content of bioactive tryptophan-derived compounds in wine fermentations

In recent years, the presence of molecules derived from aromatic amino acids in wines has been increasingly demonstrated to have a significant influence on wine quality and stability. In addition, interactions between different yeast species have been observed to influence these final properties. In this study, a screening of 81 yeast strains from different environments was carried out to establish a consortium that would promote the improvement of indolic compound levels in wine. Two strains, Saccharomyces uvarum and Saccharomyces eubayanus, with robust fermentative capacity were selected to be combined with a Saccharomyces cerevisiae strain with a predisposition towards the production of indolic compounds. Fermentation dynamics were studied in pure cultures, co-inoculations and sequential inoculations, analysing strain interactions and end-of-fermentation characteristics. Fermentations showing significant interactions were further analyzed for the resulting indolic compounds and aroma profile, with the aim of observing potential interactions and synergies resulting from the combination of different strains in the final wine. Sequential inoculation of S. cerevisiae after S. uvarum or S. eubayanus was observed to increase indolic compound levels, particularly serotonin and 3-indoleacetic acid. This study is the first to demonstrate how the formation of microbial consortia can serve as a useful strategy to enhance compounds with interesting properties in wine, paving the way for future studies and combinations.

Influence of Galvanized Steel on Kombucha Fermentation: Weight Loss Measurements, Scanning Electron Microscopy Analysis, Corrosion Activity, and Phytochemical Study

This study aimed to investigate the influence of galvanized steel coupons on black tea kombucha fermentation. As a secondary objective, the corrosion activity of the fermented medium at different stages of fermentation was investigated. The results revealed significant interactions among microorganisms, the metal, and the fermented medium. On one hand, mass loss measurement, scanning electron microscopy (SEM) analysis, and released zinc and iron ion analysis showed the deterioration of galvanized steel coupons. On the other hand, HPLC-RI analysis showed that the presence of steel coupons improved the kinetics of fermentation. The chemical composition and bioactivity of kombucha were also influenced by the presence of galvanized steel. The results showed the detection of eleven phenolic compounds by HPLC-DAD, including trihydroxyethylrutin, methyl 3,5-dihydroxybenzoate, and ethyl 4-hydroxy-3-cinamate, which were found only in kombucha in the presence of galvanized steel (K+GS). In addition, a total of 53 volatile compounds were detected by GC-MS before and after derivatization, including eleven constituents identified for the first time in K+GS. Concerning antioxidant activity, a higher percentage of inhibition against the DPPH radical was attributed to the ethyl acetate extract found in K+GS (IC50 = 8.6 µg/mL), which could suggest the formation of inhibitors. However, according to the electrochemical findings, the corrosion current density increased threefold during the fermentation process compared to acidified black tea, indicating that corrosion activity was promoted in the kombucha medium and suggesting several competing phenomena between corrosion and inhibition.

Thermophilic combined bioproduction of ethanol and hydrogen utilizing sugarcane bagasse

Research addressing investigation of environment-friendly and efficient fuel reservoirs substituting depleting fossil fuels is at-work worldwide. For this purpose, it is of ultimate requirement to establish cost-effective biofuel fermentative processes using renewable lignocellulosic bio-wastes as feedstock. The present investigation compacts the employment of Clostridium thermocellum DSMZ1313, for bench-scale co-production of bioethanol and biohydrogen (bioH2) under non-aseptic thermophilic conditions. In our previous study, the fermentation kinetics have been studied aseptically in bench-scale stirred-tank bioreactor with same fermentative bacterium under optimized levels of the key fermentation factors employing sugarcane bagasse (SCB) in the fermentation medium. In the current investigation, for co-production of bioethanol and bioH2, batch fermentation was carried as free cell approach in subsequent bioreactor’s modifications that resulted in enhanced biofuels’ yields aseptically. These include the incorporation of immobilized cells fibrous bed bioreactor (FBB) that caused 20.465% enhanced ethanol and 27.27% higher level of hydrogen, followed by substrate addition (fed-batch fermentation) resulted in 61.79% increased ethanol and 74.074% better hydrogen production. Selective stripping of the inhibitory metabolites by in-situ gas-stripping was also performed that resulted in 94.58% increased ethanol and 105.38% elevated hydrogen level. Finally, under non-aseptic thermophilic fermentation conditions, 16.07% reduced ethanol whereas 14.7% elevated hydrogen levels were obtained in comparison with aseptic fermentation conditions. The simultaneous formation of bioethanol and bioH2 by SCB usage as biofuels’ feedstock from C. thermocellum-DSMZ1313 under non-aseptic settings has appeared a potentially sustainable recourse to produce environmentally friendly energy sources. To overcome the non-sterile fermentation processes’ inefficiencies, further studies might prove useful for active large scale deployment of waste biomass-to-biofuel.

In vitro Evaluation of Different Levels of Cashew (Anacardium occidentale) Nut Meal Supplementation on Rumen Fermentation Kinetics and Digestibility

Background: Globally, safeguarding food and nutritional security of ever increasing population demands sustainable crop and livestock production. While urbanization, decrease in cultivable land and stiff feed-fuel-food competition accompanied with skyrocketing price of conventional feedstuffs hinders the sustainable livestock production. Hence, it necessitates search and exploration of alternative feed resources along with judicious utilization of existing feed resources. In this context, Cashew nut meal (CNM) is one such alternative feed resource but the studies pertaining to its optimum level of inclusion in animal diet is scanty. Therefore, the study was conducted to assess the effect of incorporating varying levels of cashew nut meal (CNM) as a supplement on in vitro rumen fermentation kinetics and digestibility. Methods: Seven distinct compounded feed mixtures (CFM) were formulated, with CNM progressively replacing 0 (C0), 10 (C1), 20 (C2), 30 (C3), 40 (C4), 50 (C5), and 60 (C6) per cent of the soybean meal (SBM) protein present in the control CFM. Additionally, seven experimental complete diets (T0 to T6) were prepared by blending these CFM with Super Napier (Pennisetum purpureum x Pennisetum glaucum) hay in a 40:60 ratio. These diets were subjected to rumen in vitro gas production (RIVGP) study with cumulative gas production measured at 0, 2, 4, 6, 8, 12, 16, 24, 36, 48, 60, 72 and 96 h post-incubation. Subsequently, in vitro dry matter digestibility (IVTDMD) and neutral detergent fiber digestibility (NDFD) of the diets were determined using a modified in vitro two-stage technique. Later, total volatile fatty acids (TVFA) were estimated using gas chromatography. Result: Analysis of chemical composition revealed that CNM contains good protein of 256.5 g/kg. The potential gas production (D) and the rate and extent of gas production (c) for diets containing CNM ranged from 54.63 to 60.24 mL and 0.036 to 0.043 h-1, respectively. IVTDMD and NDFD analysis of the seven diets fell within the range of 79.12% to 80.80% and 64.72% to 66.47%, respectively. The estimated TVFA for seven diets ranged from 17.87 to 23.65 mM. Further, the metabolisable energy (ME) of diets ranged from 7.89 to 8.08 MJ/kg DM. Importantly, no significant differences were observed in rumen fermentation kinetics parameters, IVTDMD, NDFD and TVFA among treatments (T0 to T6). In conclusion, cashew nut meal could be used as an alternative to soybean meal in compounded feed mixtures of ruminants up to 30% (w/w) without any adverse effect on rumen fermentation pattern and digestibility.