Semi-continuous Culture System Research Articles

Rumen Fermentation of Feed Mixtures Supplemented with Clay Minerals in a Semicontinuous In Vitro System.

Simple SummaryMineral clays are included in the diets of ruminants to maintain health and improve productive performances. The inclusion of several types of mineral clay (zeolite, Z; bentonite, B; and sepiolite, S) in diets with different concentrate-to-forage proportions (65:35, HC, and 35:65, HF) was tested in vitro. In HC diets, the effect of Z manifested in a higher pH in the first part of fermentation, which can be related to a more stable rumen environment. The extent of substrate fermentation was lowest with S when added to the HC diet but was lowest with B when added to the HF diet. The response of the rumen environmental conditions and the extent of fermentation depends on the interaction between the type of clay and the proportion of concentrate and forage in an animal’s diet.Interest in using clays in the diets of ruminants to improve health and performance is increasing. The microbial fermentation of 65:35 (HC) or 35:65 (HF) concentrate:forage feeds, alone or with zeolite (Z), bentonite (B), or sepiolite (S), was studied in an in vitro semicontinuous culture system. The medium pH was allowed to drop for the first 6 h and was gradually buffered thereafter. For the HC diet, the medium pH was higher with Z throughout incubation (p < 0.05). Similar results were observed for the HF diet, but with lower differences between the additives. Throughout incubation, the volume of gas produced was higher with HC than HF (p < 0.05). The gas volume with S was the lowest (p < 0.05) for HC, whereas for HF it was lowest with B from 8 h onwards (p < 0.05). No treatment differences (p > 0.05) were observed in dry matter disappearance, microbial mass, or volatile fatty acids. However, the inclusion of B in HC reduced the ammonia concentration at 6 and 12 h with respect to C (p < 0.05). The inclusion of zeolite as an additive in the diets of ruminants stabilizes the rumen environment during the first stages of fermentation in terms of pH and ammonia concentration, especially in high-concentrate diets. The buffering effect of bentonite and sepiolite was lower, and both might reduce ruminal microbial fermentation, depending on the concentrate proportion.

High intensity of light: A potential stimulus for maximizing biomass by inducing photosynthetic activity in marine microalga, Tetraselmis tetrathele

The current research aimed to increase biomass production by manipulating the light intensity between 300 and 2500 μmol m−2 s−1 into a semi-continuous culture system. The growth productivity, photosynthetic performance, pigments, lipids, and fatty acids compositions of Tetraselmis tetrathele were closely investigated. This microalga could tolerate high light intensity (1500 μmol m−2 s−1), where the light intensity per cell ranged 13 μmol m−2 s−1 g-dw−1 cell−1 produced 2.92–3.34 g-dw L−1 of dry-cell weight during steady-state growth condition, approximately 1.8 times higher than the condition at 300 μmol m−2 s−1. Interestingly, maximal electron transport rate of photosystem II (ETRmax) was induced to reflect the photoacclimation activity and accompanied with variations in pigments, lipids, and fatty acids profile to protect cells from photo-oxidative damage. The scavenging role of β-carotene as a vital photoprotective pigment was achieved upon exposure to excessive light, about 1.9-fold higher than 300 μmol m−2 s−1 light intensity.

Robust cyst germination induction in Haematococcus pluvialis to enhance astaxanthin productivity in a semi-continuous outdoor culture system using power plant flue gas

The microalgae Haematococcus pluvialis biologically converts CO2 into natural astaxanthin that possesses a strong antioxidant activity; its low carbon footprint and economic viability have allowed it to garner great attention. However, low efficiency of the cultivation process is a major hurdle in its commercial production. Here, additional nitrogen was provided to fully grown cells to induce efficient cyst germination, thereby rapidly increasing the number of cells containing astaxanthin. After germination, these cells were rapidly converted from zooids to cysts by nitrogen depletion, while maintaining a steady astaxanthin content of 5.5%. Consequently, a 2.1-fold increase in astaxanthin productivity in comparison with that in a batch culture was achieved. Moreover, the germination-based semi-continuous process yielded 2.6 times higher astaxanthin productivity in a large-scale culture using power plant flue gas and a polymeric photobioreactor. This study provides a promising cultivation strategy for the commercial mass production of natural astaxanthin.

Effects of partially replacing grass silage by lucerne silage cultivars in a high-forage diet on ruminal fermentation, methane production, and fatty acid composition in the rumen and milk of dairy cows

Lucerne silages of the Kometa and Verko cultivars were investigated in four consecutive experiments to evaluate their effects on ruminal fermentation and fatty acid (FA) proportions in the rumen fluid and milk of dairy cows. Initially, two successive in vitro experiments were performed using a semicontinuous culture system (RUSITEC). In Experiment 1, the treatments were: (1) MGS: a high-forage diet (65:35 forage:concentrate ratio; DM basis) containing maize silages (MS) and grass silages (GS) as the main forage sources, (2) MKLS: a high-forage diet containing MS and Kometa lucerne silage (KLS) as the main forage sources; and (3) sMKLS: a high-forage diet containing MS and KLS as the main forage sources and supplemented with sufficient saponin extract powder from KLS to give a saponin content equal to the in the KLS. The treatments in Experiment 2 (MGS, MVLS, or sMVLS) were similar to those in Experiment 1, except that Verko Lucerne silage (VLS) and its saponin extract were used. Methane concentration statistically insignificant decreased (P = 0.97) as a result of the MKLS treatment, while digestible dry matter (DDM) was increased (P = 0.002) for MKLS and sMKLS. However, neither methane concentration nor DDM were affected by MVLS or sMVLS. We also performed two in vivo experiments: in Experiment 3, we used six cannulated Polish Holstein-Friesian cows fitted with rumen cannulas, and in Experiment 4, we used 54 productive Polish Holstein-Friesian cows. The treatments for these two experiments were based on partial replacement of GS with KLS or VLS in the high-forage diet containing MS, as described earlier: MGS, MKLS, and MVLS. In Experiment 3, the methane concentration decreased (P < 0.001) for both MKLS and MVLS, with the diets lowering the total bacterial and protozoal counts and the total methanogens (P ≤ 0.002). Interestingly in Experiment 4, only MVLS led to a decrease in fat content and energy (P ≤ 0.02). MKLS and MVLS were also associated with lower levels of milk polyunsaturated fatty acid (P < 0.001) and higher levels of milk saturated fatty acid (P < 0.001). MKLS had more promising fatty acid composition than MVLS, with clearer methane mitigation. In conclusion, the Kometa lucerne silages inhibited methane emission and microbial population, but at the cost of increasing the saturated fatty acids in the milk fat.

Growth Rate-dependent Cell Death of Diatoms due to Viral Infection and Their Subsequent Coexistence in a Semi-continuous Culture System.

Viral infections are a major factor in diatom cell death. However, the effects of viruses on diatom dynamics remain unclear. Based on laboratory studies, it is hypothesized that virus-induced diatom mortality is dependent on the diatom growth rate. The present study aimed to elucidate the relationship between the diatom growth rate and virus-induced mortality using model systems of the marine planktonic diatom, Chaetoceros tenuissimus and its infectious viruses. We also examined the fate of diatom populations in a semi-continuous dilution culture system, in which host growth rates were controlled at 0.69, 2.08, and 3.47 day–1. Diatom populations gradually decreased following the viral inoculation of each culture system, and virus-induced mortality inversely correlated with the diatom growth rate. Furthermore, the viral burst size was slightly higher in lower growth rate cultures. These results suggested that the host physiological status related to the growth rate affected viral infection and proliferation. Diatom populations were not completely lysed or washed out in any of the dilution systems; they showed steady growth in the presence of infectious viruses. This may be partially explained by defective interference particles from viruses and cell debris. The present results indicate that diatoms in dilution environments maintain their populations, even under viral pressure. Moreover, diatom populations with a low growth rate may partially sustain higher growth populations through nutrient recycling following virus-induced cell death. The results of the present study provide insights into diatom dynamics in natural environments in the presence of infectious viruses.

Microalgal paste production of the diatom Chaetoceros calcitrans using electrolytic flocculation method at optimum culture conditions

The optimum culture conditions of the local strain Chaetoceros calcitrans were determined to improve biomass and reduce cost of production. Under outdoor culture conditions, higher cell density was attained when the cultures were enriched with Tungkang Marine Research Laboratory (TMRL) medium composed of cheap technical grade reagents and cultured at 25 g L−1 salinity. The cultures were lighted with two 40 W cool-white GE fluorescent tubes (24–35 μmol photon m−2 s−1). Using semi-continuous culture system under established optimum culture conditions, C. calcitrans can be re-cultured thrice and concentrated at each culture cycle using electrolytic flocculation method to produce 4.6 kg m−3 of diatom paste. The viability of concentrated C. calcitrans after 3 months of storage was comparable to live diatom cells. Simple preservation technique by low-temperature storage is convenient for storing algal concentrates for use as starter cultures and for feeding invertebrates. The paste costs USD 8.24 kg−1 inclusive of the assets and flocculation materials for culturing and harvesting the diatom, respectively. This study established the suitable conditions for mass culture of C. calcitrans and produced concentrated diatoms in paste form that is readily available for aquaculture hatcheries at a lower cost.

Effects of fermented milk treatment on microbial population and metabolomic outcomes in a three-stage semi-continuous culture system

We investigated the impact of a fermented milk product on gut microbiota and their metabolism in 3 different conditions of the colon with a systemic viewpoint. An in vitro semi-continuous anaerobic cultivation was used to assess the colon compartment-specific influence of fermented milk, followed by a multiomics approach combining 16S rDNA amplicon sequencing and nuclear magnetic resonance (NMR) spectroscopy. The microbiome profiling and metabolomic features were significantly different across three colon compartments and after fermented milk treatment. Integrative correlation analysis indicated that the alteration of butyrate-producing microbiota (Veillonella, Roseburia, Lachnospira, and Coprococcus) and some primary metabolites (butyrate, ethanol, lactate, and isobutyrate) in the treatment group had a strong association with the fermented milk microorganisms. Our findings suggested that fermented milk treatment significantly affected microbial population in an in vitro cultivation system as well as the colonic metabolome in different ways in each of colon compartment.

Chlorella vulgaris (Chlorophyta) Suşlarının Kesikli Kültür Sisteminde Yığın Kültürlerinin Üretimi Üzerine Bir Çalışma

In this study, it is aimed to isolate Chlorella vulgaris strain, a single-celled green algae that is common in freshwater deposits, to establish culture conditions and to obtain batch cultures. C. vulgaris has been used in food, cosmetics and pharmaceutical industries as well as become encouraging for the production of biodiesel and the treatment of wastewater in recent years. C. vulgaris strains isolated from freshwater deposits were cultivated in a semi-continuous culture system of 100, 200, 500, 1000, 2000 and 4000 ml. Subsequently growth factors such as initial inoculum amount of the strains, appropriate pH, temperature and ventilation were tested in order to optimize the conditions. The highest value in the cell counts of 4000 ml batch cultures at the 120 th hours was determined as 6.8x10 4 h/ml in AUFFH strain respectively the others were as follows: TOH 6.7x10 4 h/ml, UIK 6.3x10 4 h/ml, GURH 6.2x10 4 h/ml and GUMSH 6.1x10 4 h/ml. The highest amount in terms wet weight for 4000 ml batch cultures was obtained as AUFFH 152 (g/2000 ml), this value was followed by TOH 129.6 (g/2000 ml), GURH 120.8 (g/2000 ml), GUMSH 84.3 (g/2000 ml), UIK 48.8 (g/2000 ml).

094 The effect of two additives on ruminal fermentation using a semicontinuous culture system

094 The effect of two additives on ruminal fermentation using a semicontinuous culture system

560 The effect of two additives on ruminal fermentation using a semi-continuous culture system

Seven 37-d trials tested the effect of nitrate (NIT) and monensin (MON) in diets commonly fed to beef (BEEF; 10:90 forage to concentrate; 3 trials) and dairy cattle (DAIRY; 50:50 forage to concentrate; 4 trials) on rumen fermentation and methane (CH4) emissions. Additives (0, 1.25 and 2.5% diet DM of NIT; 0 and 4 mg/L of MON) were tested alone and combined (NIT + MON; 6 total treatments; 3 replicates per treatment). Rumen fluid was pooled from 5 non-adapted lactating cows fed 50:50 forage to concentrate diet 3 h after morning feeding, and 1 L of processed inoculum was transferred to 2.2-L vessels. Treatment diets were added to nylon bags which remained in the anaerobic fermentation system for 48 h. Buffer was infused into vessels at 70 ml/h. Gas production and composition and VFA were measured daily. Ammonia nitrogen (NH3-N) and DMD were measured twice weekly. For BEEF and DAIRY trials, when compared to control, NIT reduced CH4production (33.5 vs 43.5 and 24.7 vs 32.1 mM/d, respectively;P<0.01; SEM = 1.5) and NH3-N (6.6 vs 8.1 and 17.1 vs 21.0 mg/dL, respectively;P<0.01; SEM = 0.6) while MON reduced CH4production (26.6 vs 43.5 and 26.3 vs 32.1mM/d, respectively;P<0.01), butyrate (12.6 vs 14.9 and 16.1 vs 19.4 mM/d, respectively;P<0.01; SEM = 0.5), acetate to propionate ratio (1.6 vs 1.9 and 1.6 vs 2.0, respectively;P<0.01; SEM = 0.06) and increased propionate (29.6 vs 26.2 and 26.8 vs 22.2 mM/d, respectively;P<0.01; SEM = 0.6) and total VFA (50.7 vs 48.1 and 38.3 vs 35.4 mM/d, respectively;P<0.01; SEM = 1.9). The combination of NIT+MON in BEEF and DAIRY trials further reduced CH4(19.3 vs 43.5 and 21.3 vs 32.1 mM/d, respectively;P<0.01) and increased acetate (51.2 vs 49.5 mM/d; P = 0.07 and 53.7 vs 49.9 mM/d;P<0.01, respectively; SEM =0.9). For BEEF only, compared to control, NIT reduced DMD at higher doses (72.3 vs 74.3 g/100g DM;P<0.05; SEM = 1.4) and NIT+MON increased total VFA at lower doses (55.4 vs 48.1 mM;P<0.01). For DAIRY, butyrate was reduced by NIT (16.1 vs 19.4 mM/d; P < 0.01) and further reduced by NIT+MON (15.2 vs 19.4 mM/d;P<0.01). The combination of NIT+MON enhanced CH4reduction and increased acetate molar ratio. When NIT was present at higher doses, DMD was reduced. The combination of NIT+MON reduced butyrate in DAIRY trials and, at lower doses, increased total VFA production in BEEF trials.

Growth Characteristics of Mixotrophic Scenedesmus acuminatus under Semi-Continuous Culture System

The purpose of this study was to determine optimum value of aeration, acetate dosage, and CO2 input for the cultivation of Scenedesmus acuminatus;. Highest specific growth rate and maximum biomass productivity was obtained by the aeration of 0.72 vvm and lower specific growth rates and maximum biomass productivity were obtained for other aeration tests. When putting 0.3 M of ammonium acetate in JM medium, the highest specific growth rate and maximum biomass productivity were obtained. CO2 input tests were performed during semi-continuous culturing tests. The highest specific growth rate (0.460 d-1) and maximum biomass productivity (0.936 g L-1 d-1) were obtained after replacing 50% of solution with 0.3 M of acetate solution for CO2 input tests. However, more dilutions after the first dilution resulted in lower specific growth rate and maximum biomass productivity. In aeration tests, the highest specific growth rate (0.381 d-1) and maximum biomass productivity (0.253 g L-1 d-1) were obtained when cultivating it with JM medium, but the specific growth rate and maximum biomass producitivty were significantly decreased when 50% of solution was replaced by acetate containing solution. Key words: Scenedesmus acuminatus, Semi-Continuous Cultivation, Carbon Dioxide, Nitrogen, Phosphate, Acetate

Screening for enhanced astaxanthin accumulation among Spirulina platensis mutants generated by atmospheric and room temperature plasmas

In this study, a high-throughput screening procedure was employed to generate mutants of Spirulina platensis for enhanced astaxanthin production using an atmospheric and room temperature plasma (ARTP) based on random mutagenesis process. The optimal culture conditions for cultivation of S. platensis in the laboratory were established to be 29°C, 6.3×10−3μmol/cm2/s light intensity and a semi-continuous culture system. On the basis of the ARTP screening procedure, a mutant strain (Sp-A1) was successfully isolated, which showed astaxanthin production of 45.88±1.56μg/g, a 196% increase over that of the original wild type strain (15.50±1.52μg/g). The mutant strain accumulated higher content of chlorophyll a than that of the original wild type strain, whereas the β-carotene and polysaccharide contents as well as the superoxide dismutase (SOD) activity of the mutant strain were slightly lower. Under a single stress of 0.625g/L NaNO3, astaxanthin accumulation of mutant strain Sp-A1 reached 0.038±0.002μg/mL after 7days of culture, which was equivalent to 142.50±0.04μg/g of the astaxanthin content versus the dried S. platensis weight. This study demonstrates that ARTP is a novel powerful mutagenesis tool to generate S. platensis strains for increased yields of astaxanthin and may, therefore, play an important role in the enhanced expression of astaxanthin in microbial hosts.

1607 Effect of nitrate, monensin, and the combination of additives on rumen fermentation using a semicontinuous culture system

1607 Effect of nitrate, monensin, and the combination of additives on rumen fermentation using a semicontinuous culture system

Rumen fermentation, methane concentration and fatty acid proportion in the rumen and milk of dairy cows fed condensed tannin and/or fish-soybean oils blend

Two experimental factors (extract from Vaccinium vitis idaea (VVI) and blend of fish-soybean oils) were investigated in three consecutive experiments to monitor their effects on rumen fermentation and fatty acid (FA) proportions in the rumen fluid and milk. Firstly, in vitro experiment was performed using a semicontinuous culture system (RUSITEC). Four treatments were included: (1) CON—control diet without experimental factors; (2) VVI—control diet with 4.5g of VVI/kg of DM; (3) FSM—control diet with 30g of fish and soybean oils blend/kg of DM; (4) MIX—control diet with 4.5g of VVI/kg of DM and 30g of oils blend/kg of DM. The proportions of C18:1 t10, C18:1 t11 and C18:1 c9 FA increased (P<0.002) in FSM and MIX treatments. Abundance of Butyrivibrio fibrisolvens and Butyrivibrio proteoclasticus was significantly reduced in three treatments (VVI, FSM, MIX; P<0.019). Moreover, the MIX significantly decreased methane concentrations by 21% in comparison with the CON (P<0.002). Based on preliminary in vitro results from the first experiment, the second, in vivo experiment was conducted using four Polish Holstein-Friesian cows fitted with rumen cannulas. Cows received the diet as a partial mix ration in two variants: (1) CON diet without supplementation (2) MIX diet containing a mixture of VVI dried leaves extract as a source of condensed tannins (4.83g/kg DM of total diet) and a blend of fish-soybean oils as a source of unsaturated FA (32.2g/kg) DM of total diet. For the MIX treatment, the proportions of C18:2 c9-c12, C18:2 c9-t11 and C18:2 t10-c12 in the rumen fluid were affected (P<0.05), whereas the DNA concentration for B. fibrisolvens and B. proteoclasticus was not changed. Thus the MIX treatment exerted an antimicrobial activity by decreasing protozoa and methanogen numbers, thereby reducing rumen methane production. Finally, the third, production experiment was conducted on 12 lactating Polish Holstein-Friesian cows subjected to the same treatment as the cannulated cows in the second experiment. The MIX treatment did not modify the proportions of majority of the unsaturated FA in milk. The MIX treatment also did not change expression of the six investigated genes: acetyl-CoA carboxylase 1 (ACACA), fatty acid synthase (FASN), lipoprotein lipase (LPL), stearoyl-CoAdesaturase (SCD), fatty acid desaturase 1 (FADS1), fatty acid elongase 5 (ELOVL5). In conclusion, unexpectedly, the MIX treatment did not change the milk FA proportion, and this phenomenon could be attributed to a lack of effects of the both provided supplements. In spite of that, the MIX treatment significantly decreased the methanogenesis.

Productivity, biochemical composition and biofiltering performance of agarophytic seaweed, Gelidium elegans (Red algae) grown in shrimp hatchery effluents in Malaysia

Aquaculture systems may release large amounts of nutrients into the marine ecosystem that can lead to eutrophication. Many seaweed species are efficient in reducing the nutrient concentration in aquaculture waste. In this study, the agarophyte Gelidium elegans originating from Korea was investigated for bioremediation of tiger shrimp (Penaeus monodon) broodstock effluent (SBE) in a shrimp hatchery in Malaysia. The G. elegans was cultivated in SBE using a semi-continuous culture system to evaluate the effects of elevated nutrients on the biomass, growth rate, quality and quantity of agar, pigment content and biochemical composition of seaweed. In the treatment containing G. elegans, pollutant nutrient concentration was reduced by 100%, and by 78.7%, 47.9%, and 19.6% for ammoniacal-nitrogen, nitrite, nitrate, and orthophosphate, respectively. The seaweed grew well (1.4 ±0.3% d-1) in SBE and produced appreciable amounts of protein (3.8% DW), carbohydrate (41.4 % DW) and agar (25.9% DW), that were significantly enhanced when cultured in the SBE compared to control. The photosynthetic performance of G. elegans assessment using a Diving-PAM showed the healthy condition of the grown seaweed without any indication of stress in shrimp hatchery effluent. Results showed that G. elegans has biofiltering and bioremediation potential for the shrimp hatchery effluent.

Lycopene overproduction and in situ extraction in organic-aqueous culture systems using a metabolically engineered Escherichia coli.

Lycopene is an import ant compound with an increasing industrial value. However, there is still no biotechnological process to obtain it. In this study, a semi-continuous system for lycopene extraction from recombinant Escherichia coli BL21 cells is proposed. A two-phase culture mode using organic solvents was found to maximize lycopene production through in situ extraction from cells. Within the reactor, three phases were formed during the process: an aqueous phase containing the recombinant E. coli, an interphase, and an organic phase. Lycopene was extracted from the cells to both the interphase and the organic phase and, consequently, thus enhancing its production. Maximum lycopene production (74.71 ± 3.74 mg L−1) was obtained for an octane-aqueous culture system using the E. coli BL21LF strain, a process that doubled the level obtained in the control aqueous culture. Study of the interphase by transmission electron microscopy (TEM) showed the proteo-lipidic nature and the high storage capacity of lycopene. Moreover, a cell viability test by flow cytometry (CF) after 24 h of culture indicated that 24 % of the population could be re-used. Therefore, a batch series reactor was designed for semi-continuous lycopene extraction. After five cycles of operation (120 h), lycopene production was similar to that obtained in the control aqueous medium. A final specific lycopene yield of up to 49.70 ± 2.48 mg g−1 was reached at 24 h, which represents to the highest titer to date. In conclusion, the aqueous-organic semi-continuous culture system proposed is the first designed for lycopene extraction, representing an important breakthrough in the development of a competitive biotechnological process for lycopene production and extraction.Electronic supplementary materialThe online version of this article (doi:10.1186/s13568-015-0150-3) contains supplementary material, which is available to authorized users.

Enhanced biodiesel production in Neochloris oleoabundans by a semi-continuous process in two stage photobioreactors.

Under autotrophic conditions, highly productive biodiesel production was achieved using a semi-continuous culture system in Neochloris oleoabundans. In particular, the flue gas generated by combustion of liquefied natural gas and natural solar radiation were used for cost-effective microalgal culture system. In semi-continuous culture, the greater part (~80%) of the culture volume containing vegetative cells grown under nitrogen-replete conditions in a first photobioreactor (PBR) was directly transferred to a second PBR and cultured sequentially under nitrogen-deplete conditions for accelerating oil accumulation. As a result, in semi-continuous culture, the productivities of biomass and biodiesel in the cells were increased by 58% (growth phase) and 51% (induction phase) compared to the cells in batch culture, respectively. The semi-continuous culture system using two stage photobioreactors is a very efficient strategy to further improve biodiesel production from microalgae under photoautotrophic conditions.

Effects of hydrolyzed and live yeasts on rumen microbial fermentation in a semicontinuous culture system (Rusitec)

The objective of this study was to investigate the effects of hydrolyzed and live forms of yeast products from Saccharomyces cerevisiae on in vitro fermentation of a 50:50 forage:concentrate substrate using the rumen simulation technique (Rusitec). The Rusitec system consisted of nine fermentation vessels: three of them received daily 0.5 g/L hydrolyzed yeast, three vessels received daily 0.5 g/L live yeast, and three vessels received no additives (control). After an adaptation period of 7 days, the main fermentation characteristics were evaluated for 7 consecutive days. Ruminal pH was decreased (P < 0.05) by hydrolyzed yeast, whereas no effects were observed after live yeast treatment. Both hydrolyzed and live yeasts tended to increase butyrate production (P = 0.052). Acetate to propionate ratio was significantly higher (P < 0.05) for live yeast. Both products increased NH3-N concentration, and it was significantly higher (P < 0.05) in live yeast in comparison with that in hydrolyzed yeast. Digestibility of dry matter was not significantly affected by both yeast treatments. Overall, these results showed that different types of yeast products in terms of their viability status had significant actions in ruminal microbial metabolism in different ways.

The Impact of Injections of Different Nutrients on the Bacterial Community and Its Dechlorination Activity in Chloroethene-Contaminated Groundwater.

Dehalococcoides spp. are currently the only organisms known to completely reduce cis-1,2-dichloroethene (cis-DCE) and vinyl chloride (VC) to non-toxic ethene. However, the activation of fermenting bacteria that generate acetate, hydrogen, and CO2 is considered necessary to enhance the dechlorination activity of Dehalococcoides and enable the complete dechlorination of chloroethenes. In the present study, we stimulated chloroethene-contaminated groundwater by injecting different nutrients prepared from yeast extract or polylactate ester using a semicontinuous culture system. We then evaluated changes in the bacterial community structure and their relationship with dechlorination activity during the biostimulation. The populations of Dehalococcoides and the phyla Bacteroidetes, Firmicutes, and Spirochaetes increased in the yeast extract-amended cultures and chloroethenes were completely dechlorinated. However, the phylum Proteobacteria was dominant in polylactate ester-amended cultures, in which almost no cis-DCE and VC were dechlorinated. These results provide fundamental information regarding possible interactions among bacterial community members involved in the dechlorination process and support the design of successful biostimulation strategies.

Effects of olive leaf extract on rumen microbial fermentation in in vitro semi-continuous culture system (RUSITEC)

Bu araştırmada rumen simulasyon tekniği (RUSITEC) kullanılarak zeytin yaprağı ekstraktının % 50 kaba yem % 50 konsantre yemden oluşan bir rasyonun in vitro fermantasyonu üzerine etkilerinin araştırılması ve bu etkilerin monensinin etkileri ile karşılaştırılması amaçlandı. Rusitec sistemde 8 fermenter kullanıldı: Bunlardan ilk ikisine günlük 150 mg (OLE-H), diğer ikisine ise günlük 15 mg (OLE-L) zeytin yaprağı ekstraktı ilave edildi. Kalan 4 fermenterden ikisine günlük 5 mg monensin (MON, pozitif kontrol) ilavesi yapılırken, son iki fermentere hiçbir ilave yapılmayıp kontrol (CTR) olarak kullanıldı. Yedi günlük adaptasyon fazından sonra, 7 gün boyunca temel fermantasyon parametreleri belirlendi. Deneme grupları arasında pH ve organik madde sindirilebilirliği açısından istatistiksel bir farklılık bulunmadı. MON propiyonat üretimini istatistiksel olarak belirgin bir şekilde artırırken (p < 0,05), asetat ve bütirat üretimleri, asetatın propiyonata oranı, protozoon sayısı ve NH3-N konsantrasyonunu belirgin bir şekilde azalttı (p < 0,05). CTR ile karşılaştırıldığında, OLE’nin her iki konsantrasyonu da toplam uçucu yağ asidi (UYA) ve propiyonat üretimlerini istatistiksel olarak anlamlı bir şekilde arttırdı (p < 0,05). Ancak OLE-H bütirat üretimi ve toplam protozoon sayısını azalttı (p < 0,05). Bu araştırmanın sonuçlarına dayanarak zeytin yaprağı ekstraktının yarı-sürekli rumen simulasyon kültür sisteminde bazı fermantasyon parametreleri üzerinde olumlu etkiler oluşturduğunu, dolayısıyla rumendeki fermantasyon verimliliğini artırabileceğini söyleyebiliriz