1
|
Muthui SW, Wei L, Ochieng WA, Linda EL, Otieno DO, Nyongesa EW, Liu F, Xian L. The distinctive level of interaction between carbon and nitrogen metabolisms in the leaves of submerged macrophytes plays a key role in ammonium detoxification. Aquat Toxicol 2024; 268:106840. [PMID: 38278063 DOI: 10.1016/j.aquatox.2024.106840] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/19/2023] [Revised: 01/08/2024] [Accepted: 01/12/2024] [Indexed: 01/28/2024]
Abstract
Possible ammonium detoxification mechanisms have been proposed recently, on submerged macrophytes, evidently illustrating that glutamate dehydrogenase (GDH) plays a greater role in ammonium detoxification compared to the primary glutamine synthetase/glutamate oxaloacetate transaminase (GS/GOGAT) pathway. In the current investigation, we cultured three submerged macrophytes to extreme concentrations of [NH4+-N] of up to 50 mg/L with the aim of clarifying the interaction between carbon and nitrogen metabolisms. The activities of carboxylation enzymes pyruvate orthophosphate dikinase (PPDK) and phosphoenolpyruvate carboxylase (PEPC), in lieu of Rubisco, increased almost two-fold for ammonium tolerant species P. maackianus and M. spicatum, compared with the sensitive species P. lucens. While these enzymes are well known for their central role in CO2 fixation, their inference in conferring resistance to ammonium stress has not been well elucidated before. In this study, we demonstrate that the overproduction of PEPC and PPDK led to improved photosynthesis, better ammonium assimilation and overall ammonium detoxification in M. spicatum and P. maackianus. These findings propose likelihood for the existence of a complementary ammonium detoxification pathway that targets carbon metabolism, thus, presenting a relatively efficient linkage between nitrogen and carbon metabolisms and identify candidate species for practical restoration of fresh water resources.
Collapse
Affiliation(s)
- Samuel Wamburu Muthui
- Core Botanical Gardens/Wuhan Botanical Garden, Chinese Academy of Sciences, Wuhan, China; University of Chinese Academy of Sciences, Beijing, China; Sino-Africa Joint Research Centre, Chinese Academy of Sciences, Wuhan, China
| | - Li Wei
- Changjiang Water Resources and Hydropower Development Group (Hubei) Co., Ltd., Wuhan 430010, China
| | - Wyckliffe Ayoma Ochieng
- Core Botanical Gardens/Wuhan Botanical Garden, Chinese Academy of Sciences, Wuhan, China; University of Chinese Academy of Sciences, Beijing, China; Sino-Africa Joint Research Centre, Chinese Academy of Sciences, Wuhan, China
| | - Elive Limunga Linda
- Hubei University, School of Resources and Environmental Science, Wuhan 430074, China
| | - Duncan Ochieng Otieno
- Core Botanical Gardens/Wuhan Botanical Garden, Chinese Academy of Sciences, Wuhan, China; University of Chinese Academy of Sciences, Beijing, China; Sino-Africa Joint Research Centre, Chinese Academy of Sciences, Wuhan, China
| | - Emmanuel Waswa Nyongesa
- Core Botanical Gardens/Wuhan Botanical Garden, Chinese Academy of Sciences, Wuhan, China; University of Chinese Academy of Sciences, Beijing, China; Sino-Africa Joint Research Centre, Chinese Academy of Sciences, Wuhan, China
| | - Fan Liu
- Core Botanical Gardens/Wuhan Botanical Garden, Chinese Academy of Sciences, Wuhan, China
| | - Ling Xian
- Core Botanical Gardens/Wuhan Botanical Garden, Chinese Academy of Sciences, Wuhan, China.
| |
Collapse
|
2
|
Ochieng WA, Wei L, Wagutu GK, Xian L, Muthui SW, Ogada S, Otieno DO, Linda EL, Liu F. Transcriptome Analysis of Macrophytes' Myriophyllum spicatum Response to Ammonium Nitrogen Stress Using the Whole Plant Individual. Plants (Basel) 2023; 12:3875. [PMID: 38005772 PMCID: PMC10675724 DOI: 10.3390/plants12223875] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/19/2023] [Revised: 11/11/2023] [Accepted: 11/13/2023] [Indexed: 11/26/2023]
Abstract
Ammonium toxicity in macrophytes reduces growth and development due to a disrupted metabolism and high carbon requirements for internal ammonium detoxification. To provide more molecular support for ammonium detoxification in the above-ground and below-ground parts of Myriophyllum spicatum, we separated (using hermetic bags) the aqueous medium surrounding the below-ground from that surrounding the above-ground and explored the genes in these two regions. The results showed an upregulation of asparagine synthetase genes under high ammonium concentrations. Furthermore, the transcriptional down and/or upregulation of other genes involved in nitrogen metabolism, including glutamate dehydrogenase, ammonium transporter, and aspartate aminotransferase in above-ground and below-ground parts were crucial for ammonium homeostasis under high ammonium concentrations. The results suggest that, apart from the primary pathway and alternative pathway, the asparagine metabolic pathway plays a crucial role in ammonium detoxification in macrophytes. Therefore, the complex genetic regulatory network in M. spicatum contributes to its ammonium tolerance, and the above-ground part is the most important in ammonium detoxification. Nevertheless, there is a need to incorporate an open-field experimental setup for a conclusive picture of nitrogen dynamics, toxicity, and the molecular response of M. spicatum in the natural environment.
Collapse
Affiliation(s)
- Wyckliffe Ayoma Ochieng
- Core Botanical Gardens/Wuhan Botanical Garden, Chinese Academy of Sciences, Wuhan 430074, China; (W.A.O.); (G.K.W.); (L.X.); (S.W.M.); (D.O.O.)
- Sino-Africa Joint Research Centre, Chinese Academy of Sciences, Wuhan 430074, China
- University of the Chinese Academy of Sciences, Beijing 101408, China
| | - Li Wei
- Changjiang Water Resources and Hydropower Development Group (Hubei) Co., Ltd., Wuhan 430010, China;
| | - Godfrey Kinyori Wagutu
- Core Botanical Gardens/Wuhan Botanical Garden, Chinese Academy of Sciences, Wuhan 430074, China; (W.A.O.); (G.K.W.); (L.X.); (S.W.M.); (D.O.O.)
- Sino-Africa Joint Research Centre, Chinese Academy of Sciences, Wuhan 430074, China
- University of the Chinese Academy of Sciences, Beijing 101408, China
| | - Ling Xian
- Core Botanical Gardens/Wuhan Botanical Garden, Chinese Academy of Sciences, Wuhan 430074, China; (W.A.O.); (G.K.W.); (L.X.); (S.W.M.); (D.O.O.)
| | - Samuel Wamburu Muthui
- Core Botanical Gardens/Wuhan Botanical Garden, Chinese Academy of Sciences, Wuhan 430074, China; (W.A.O.); (G.K.W.); (L.X.); (S.W.M.); (D.O.O.)
- Sino-Africa Joint Research Centre, Chinese Academy of Sciences, Wuhan 430074, China
- University of the Chinese Academy of Sciences, Beijing 101408, China
| | - Stephen Ogada
- Institute for Biotechnology Research, Jomo Kenyatta University of Agriculture and Technology, Nairobi 00200, Kenya;
| | - Duncan Ochieng Otieno
- Core Botanical Gardens/Wuhan Botanical Garden, Chinese Academy of Sciences, Wuhan 430074, China; (W.A.O.); (G.K.W.); (L.X.); (S.W.M.); (D.O.O.)
- Sino-Africa Joint Research Centre, Chinese Academy of Sciences, Wuhan 430074, China
- University of the Chinese Academy of Sciences, Beijing 101408, China
| | - Elive Limunga Linda
- School of Resources and Environmental Science, Hubei University, Wuhan 430062, China;
| | - Fan Liu
- Core Botanical Gardens/Wuhan Botanical Garden, Chinese Academy of Sciences, Wuhan 430074, China; (W.A.O.); (G.K.W.); (L.X.); (S.W.M.); (D.O.O.)
- Sino-Africa Joint Research Centre, Chinese Academy of Sciences, Wuhan 430074, China
| |
Collapse
|
3
|
Xian L, Ochieng WA, Muthui SW, Otieno DO, Yu S, Li W, Yan X, Yu Q, Liu F. The Above-Ground Part of Submerged Macrophytes Plays an Important Role in Ammonium Utilization. Front Plant Sci 2022; 13:865578. [PMID: 35734251 PMCID: PMC9207443 DOI: 10.3389/fpls.2022.865578] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/30/2022] [Accepted: 04/26/2022] [Indexed: 06/15/2023]
Abstract
As a paradoxical nutrient in water ecosystems, ammonium can promote plants growth under moderate concentration, but excess of it causes phytotoxic effects. Previous research has revealed that glutamate dehydrogenase in the above-ground part of submerged macrophytes plays an important role in ammonium detoxification. However, the strategies of ammonium utilization at the whole plant level of submerged macrophytes are still unclear and the role of the above-ground part in nutrient utilization has not been clearly elucidated in previous studies, hence, directly influencing the application of previous theory to practice. In the present research, we combined the methods of isotopic labeling and enzyme estimation to investigate strategies of ammonium utilization by the submerged macrophytes. The results showed that when [NH4 +-N] was 50 mg L-1, 15N taken up through the above-ground parts was 13.24 and 17.52 mg g-1 DW, while that of the below-ground parts was 4.24 and 8.54 mg g-1 DW in Potamogeton lucens and Myriophyllum spicatum, respectively. The ratios of 15N acropetal translocation to uptake were 25.75 and 35.69%, while those of basipetal translocation to uptake were 1.93 and 4.09% in P. lucens and M. spicatum, respectively. Our results indicated that the above-ground part was not only the main part for ammonium uptake, but also the major pool of exogenous ammonium. Besides, the dose-response curve of GDH (increased by 20.9 and 50.2% under 15 and 50 mg L-1 [NH4 +-N], respectively) exhibited by the above-ground parts of M. spicatum indicates that it is the main site for ammonium assimilation of the tolerant species. This study identifies the ammonium utilization strategy of submerged macrophytes and reveals the important role of the above-ground part in nutrient utilization providing new insight into the researches of nutrient utilization by plants and theoretical supports for water restoration by phytoremediation.
Collapse
Affiliation(s)
- Ling Xian
- Core Botanical Gardens/Wuhan Botanical Garden, Chinese Academy of Sciences, Wuhan, China
- University of the Chinese Academy of Sciences, Beijing, China
| | - Wyckliffe Ayoma Ochieng
- Core Botanical Gardens/Wuhan Botanical Garden, Chinese Academy of Sciences, Wuhan, China
- University of the Chinese Academy of Sciences, Beijing, China
- Sino-Africa Joint Research Centre, Chinese Academy of Sciences, Wuhan, China
| | - Samuel Wamburu Muthui
- Core Botanical Gardens/Wuhan Botanical Garden, Chinese Academy of Sciences, Wuhan, China
- University of the Chinese Academy of Sciences, Beijing, China
- Sino-Africa Joint Research Centre, Chinese Academy of Sciences, Wuhan, China
| | - Duncan Ochieng Otieno
- Core Botanical Gardens/Wuhan Botanical Garden, Chinese Academy of Sciences, Wuhan, China
- University of the Chinese Academy of Sciences, Beijing, China
- Sino-Africa Joint Research Centre, Chinese Academy of Sciences, Wuhan, China
| | - Siwei Yu
- Core Botanical Gardens/Wuhan Botanical Garden, Chinese Academy of Sciences, Wuhan, China
| | - Wei Li
- Core Botanical Gardens/Wuhan Botanical Garden, Chinese Academy of Sciences, Wuhan, China
| | - Xue Yan
- Core Botanical Gardens/Wuhan Botanical Garden, Chinese Academy of Sciences, Wuhan, China
- Sino-Africa Joint Research Centre, Chinese Academy of Sciences, Wuhan, China
| | - Quan Yu
- Core Botanical Gardens/Wuhan Botanical Garden, Chinese Academy of Sciences, Wuhan, China
- Sino-Africa Joint Research Centre, Chinese Academy of Sciences, Wuhan, China
| | - Fan Liu
- Core Botanical Gardens/Wuhan Botanical Garden, Chinese Academy of Sciences, Wuhan, China
- Sino-Africa Joint Research Centre, Chinese Academy of Sciences, Wuhan, China
| |
Collapse
|
4
|
Ochieng WA, Xian L, Nasimiyu AT, Muthui SW, Ndirangu LN, Otieno DO, Wan T, Liu F. Exploring the ammonium detoxification mechanism of young and mature leaves of the macrophyte Potamogeton lucens. Aquat Toxicol 2021; 237:105879. [PMID: 34116338 DOI: 10.1016/j.aquatox.2021.105879] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/25/2020] [Revised: 05/16/2021] [Accepted: 05/23/2021] [Indexed: 06/12/2023]
Abstract
Toxicity in aquatic plants, caused by excess ammonium in the environment, is an important ecological problem and active research topic. Recent studies showed the importance of the enzyme Glutamate Dehydrogenase (GDH) in detoxifying ammonium. However, these results mainly derived from species comparisons, hence some mechanisms may have been obscured due to species differences. Our recent finding that young leaves of Potamogeton lucens were less sensitive to ammonium enrichment, than mature leaves allowed us to study ammonium detoxification within a species. We found that, unlike mature leaves, ammonium-tolerant young leaves of P. lucens could assimilate ammonium mainly through GDH. There was a 38% increase of NADH-dependent GDH in 50 mg/L ammonium concentration compared with 0.1 mg/L. Therefore, this study confirms the hypothesis that the GDH pathway plays a major role in the detoxification of ammonium in freshwater macrophytes.
Collapse
Affiliation(s)
- Wyckliffe Ayoma Ochieng
- Key Laboratory of Aquatic Botany and Watershed Ecology, Wuhan Botanical Garden, Chinese Academy of Sciences, Wuhan, Hubei 430074, PR China; Sino-Africa Joint Research Centre, Chinese Academy of Sciences, Wuhan, Hubei 430074, PR China; University of Chinese Academy of Sciences, Beijing, PR China
| | - Ling Xian
- Key Laboratory of Aquatic Botany and Watershed Ecology, Wuhan Botanical Garden, Chinese Academy of Sciences, Wuhan, Hubei 430074, PR China; University of Chinese Academy of Sciences, Beijing, PR China; Center for Plant Ecology, Core Botanical Gardens, Chinese Academy of Sciences, Wuhan, Hubei 430074, PR China
| | - Annah Timinah Nasimiyu
- Key Laboratory of Aquatic Botany and Watershed Ecology, Wuhan Botanical Garden, Chinese Academy of Sciences, Wuhan, Hubei 430074, PR China; Sino-Africa Joint Research Centre, Chinese Academy of Sciences, Wuhan, Hubei 430074, PR China; University of Chinese Academy of Sciences, Beijing, PR China
| | - Samuel Wamburu Muthui
- Key Laboratory of Aquatic Botany and Watershed Ecology, Wuhan Botanical Garden, Chinese Academy of Sciences, Wuhan, Hubei 430074, PR China; Sino-Africa Joint Research Centre, Chinese Academy of Sciences, Wuhan, Hubei 430074, PR China; University of Chinese Academy of Sciences, Beijing, PR China
| | - Leah Nyawira Ndirangu
- Key Laboratory of Aquatic Botany and Watershed Ecology, Wuhan Botanical Garden, Chinese Academy of Sciences, Wuhan, Hubei 430074, PR China; Sino-Africa Joint Research Centre, Chinese Academy of Sciences, Wuhan, Hubei 430074, PR China; University of Chinese Academy of Sciences, Beijing, PR China
| | - Duncan Ochieng Otieno
- Key Laboratory of Aquatic Botany and Watershed Ecology, Wuhan Botanical Garden, Chinese Academy of Sciences, Wuhan, Hubei 430074, PR China; Sino-Africa Joint Research Centre, Chinese Academy of Sciences, Wuhan, Hubei 430074, PR China; University of Chinese Academy of Sciences, Beijing, PR China
| | - Tao Wan
- Key Laboratory of Southern Subtropical Plant Diversity, Fairy Lake Botanical Garden, Shenzhen & Chinese Academy of Science, Shenzhen 518004, China.
| | - Fan Liu
- Key Laboratory of Aquatic Botany and Watershed Ecology, Wuhan Botanical Garden, Chinese Academy of Sciences, Wuhan, Hubei 430074, PR China; Sino-Africa Joint Research Centre, Chinese Academy of Sciences, Wuhan, Hubei 430074, PR China; Center for Plant Ecology, Core Botanical Gardens, Chinese Academy of Sciences, Wuhan, Hubei 430074, PR China.
| |
Collapse
|
5
|
Ipara BO, Otieno DO, Nyikal RA, Makokha SN. The role of unregulated chicken marketing practices on the frequency of Newcastle disease outbreaks in Kenya. Poult Sci 2020; 98:6356-6366. [PMID: 31504870 PMCID: PMC6870556 DOI: 10.3382/ps/pez463] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2019] [Accepted: 08/06/2019] [Indexed: 12/20/2022] Open
Abstract
In developing countries, chicken trade is characterized by complex chains comprising of many actors with limited biosecurity. This increases the spread of chicken diseases like Newcastle disease (ND). In Kenya, there is lack of uniformity in practices used in live bird markets, leading to increased disease outbreaks. This study aimed at assessing the effects of the chicken marketing practices on the frequency of ND outbreaks. A Poisson regression (PRM) was used on data collected from 336 traders selected using multi-stage sampling in Kakamega, Machakos, and Nairobi. Results highlight the low access of trainings and credit by traders. From the PRM results, breed composition, market channel, transportation, origin of birds, mixing of birds, slaughter of birds, disposal of waste, and housing as well as trader attributes like ND awareness, licensing, gender, and age had significant effects on the frequency of ND outbreaks. The study recommends that County governments collaborate with development partners to develop innovative ways of disseminating information on ND. The County governments should invest in market infrastructure such as slaughter facilities, special shelters and waste disposal equipment. There is also need for enforcement of biosecurity and hygiene measures through regular market inspections.
Collapse
Affiliation(s)
- B O Ipara
- Department of Agricultural Economics, University of Nairobi. P.O. Box 29053-00625, Kangemi, Nairobi, Kenya
| | - D O Otieno
- Department of Agricultural Economics, University of Nairobi. P.O. Box 29053-00625, Kangemi, Nairobi, Kenya
| | - R A Nyikal
- Department of Agricultural Economics, University of Nairobi. P.O. Box 29053-00625, Kangemi, Nairobi, Kenya
| | - S N Makokha
- Biotechnology Kabete Centre, Kenya Agricultural and Livestock Research Organization (KALRO). P. O Box 362-00902, Kikuyu. Nairobi, Kenya
| |
Collapse
|
6
|
Otieno DO, Shah NP. Endogenous β-glucosidase and β-galactosidase activities from selected probiotic micro-organisms and their role in isoflavone biotransformation in soymilk. J Appl Microbiol 2007; 103:910-7. [PMID: 17897193 DOI: 10.1111/j.1365-2672.2007.03438.x] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
AIM To compare endogenous beta-glucosidases and beta-galactosidases for hydrolysis of the predominant isoflavone glycosides into isoflavone aglycones in order to improve biological activity of soymilk. METHODS AND RESULTS beta-glucosidase and beta-galactosidase activities of probiotic organisms including Lactobacillus acidophilus ATCC 4461, Lactobacillus casei 2607 and Bifidobacterium animalis ssp. lactis Bb12 in soymilk were evaluated and correlated with the increase in concentration of isoflavone aglycones during fermentation. The concentrations of isoflavone compounds in soymilk were monitored using a Varian model high-performance liquid chromatography (HPLC) with an amperometric electrochemical detector. In all micro-organisms, beta-glucosidase activity was found greater than that of beta-galactosidase. There was an increase in the aglycone concentration with incubation time because of the apparent hydrolytic action on isoflavone glycosides. Aglycone concentration in the soymilk with L. acidophilus 4461, L. casei 2607 and B. animalis ssp. lactis Bb12, increased by 5.37-, 5.52- and 6.10-fold, respectively, after 15 h of fermentation at 37 degrees C. The maximum hydrolytic potential was also observed at 15 h of fermentation for the three micro-organims coinciding with peak activities of the two enzymes. CONCLUSIONS beta-glucosidase activity was more than 15 times higher than beta-galactosidase activity in soymilk for each of the micro-organisms during fermentation. beta-glucosidase played a greater role in isoflavone glycoside hydrolysis. SIGNIFICANCE AND IMPACT OF THE STUDY Screening for beta-glucosidase and beta-galactosidase activities among probiotics in soymilk is important for the improvement of biological activity of soymilk and in the selection of micro-organisms for use in the growing industry of functional foods and beverages.
Collapse
Affiliation(s)
- D O Otieno
- School of Molecular Sciences, Victoria University, Werribee Campus, Melbourne, Australia
| | | |
Collapse
|
7
|
Otieno DO, Shah NP. A comparison of changes in the transformation of isoflavones in soymilk using varying concentrations of exogenous and probiotic-derived endogenous ?-glucosidases. J Appl Microbiol 2007; 103:601-12. [PMID: 17714393 DOI: 10.1111/j.1365-2672.2006.03245.x] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
AIMS To compare endogenous and exogenous beta-glucosidases for the hydrolysis of the predominant isoflavone glucosides in soymilk in order to improve the biological activity. METHODS AND RESULTS beta-glucosidase activity of probiotic organisms, including Bifidobacterium animalis ssp. lactis Bb12, Lactobacillus acidophilus ATCC 4461 and Lactobacillus casei 2607 in soymilk, was evaluated and was related to the increase in the concentration of isoflavone aglycones during fermentation. The concentrations of isoflavone compounds in soymilk were monitored using a Varian model HPLC with an Amperometric electrochemical detector. The aglycone composition, also known as aglycone equivalent ratio, has been considered to be important for the delivery of health benefits of isoflavones, and was monitored during the fermentation of soymilk. Comparison of the hydrolytic effectiveness of both exogenous and endogenous enzyme during 4-h incubation in soymilk was conducted using the Otieno-Shah (O-S) index. Results showed that exogenous enzyme exhibited faster rate of isoflavone glucoside hydrolysis than that by endogenous enzyme. Highest O-S indices were obtained after 4, 3 and 2 h of incubation with enzyme solution having beta-glucosidase activity of 0.288 U ml(-1), 0.359 U ml(-1) and 0.575 U ml(-1), resulting into aglycone concentration increments of 5.87-, 6.07- and 5.94-fold, respectively. Conversely, aglycone concentration in the soymilk with B. animalis ssp. lactis Bb12, L. casei 2607 and L. acidophilus 4461 increased by 3.43-, 2.72- and 3.03-fold, respectively, after 4 h of fermentation at 37 degrees C. In addition, the O-S index of endogenous enzyme was much lower than that of the exogenous enzyme over the same 4-h incubation period. Optimum aglycone equivalent ratios coincided with highest O-S indices and highest aglycone concentrations in soymilk hydrolysed with exogenous enzyme. The same correlation of O-S indices and highest aglycone concentrations occurred for endogenous enzyme during the 24 h of fermentation. CONCLUSIONS Obtaining highest aglycone concentration and optimum aglycone equivalent ratio could provide a critical beginning point in clinical trials for the realization of unique health benefits of soy isoflavones. SIGNIFICANCE AND IMPACT OF THE STUDY Screening for beta-glucosidase activities of probiotics in soymilk and comparing their hydrolytic potentials with that of exogenous beta-glucosidase could find wide applications in the development of different aglycone-rich functional soy beverages.
Collapse
Affiliation(s)
- D O Otieno
- School of Molecular Sciences, Victoria University, Werribee Campus, Melbourne, Victoria, Australia
| | | |
Collapse
|
8
|
Otieno DO, Schmidt MWT, Kurz-Besson C, Lobo Do Vale R, Pereira JS, Tenhunen JD. Regulation of transpirational water loss in Quercus suber trees in a Mediterranean-type ecosystem. Tree Physiol 2007; 27:1179-87. [PMID: 17472943 DOI: 10.1093/treephys/27.8.1179] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/15/2023]
Abstract
Sap flux density in branches, leaf transpiration, stomatal conductance and leaf water potentials were measured in 16-year-old Quercus suber L. trees growing in a plantation in southern Portugal to understand how evergreen Mediterranean trees regulate water loss during summer drought. Leaf specific hydraulic conductance and leaf gas exchange were monitored during the progressive summer drought to establish how changes along the hydraulic pathway influence shoot responses. As soil water became limiting, leaf water potential, stomatal conductance and leaf transpiration declined significantly. Predawn leaf water potential reflected soil water potential measured at 1-m depth in the rhizospheres of most trees. The lowest predawn leaf water potential recorded during this period was -1.8 MPa. Mean maximum stomatal conductance declined from 300 to 50 mmol m(-2) s(-1), reducing transpiration from 6 to 2 mmol m(-2) s(-1). Changes in leaf gas exchange were attributed to reduced soil water availability, increased resistances along the hydraulic pathway and, hence, reduced leaf water supply. There was a strong coupling between changes in soil water content and stomatal conductance as well as between stomatal conductance and leaf specific hydraulic conductance. Despite significant seasonal differences among trees in predawn leaf water potential, stomatal conductance, leaf transpiration and leaf specific hydraulic conductance, there were no differences in midday leaf water potentials. The strong regulation of changes in leaf water potential in Q. suber both diurnally and seasonally is achieved through stomatal closure, which is sensitive to changes in both liquid and vapor phase conductance. This sensitivity allows for optimization of carbon and water resource use without compromising the root-shoot hydraulic link.
Collapse
Affiliation(s)
- D O Otieno
- Department of Botany, Maseno University, P.O. Box 333, Maseno, Kenya.
| | | | | | | | | | | |
Collapse
|
9
|
Otieno DO, Ashton JF, Shah NP. Isoflavone phytoestrogen degradation in fermented soymilk with selected β-glucosidase producing L. acidophilus strains during storage at different temperatures. Int J Food Microbiol 2007; 115:79-88. [PMID: 17174431 DOI: 10.1016/j.ijfoodmicro.2006.10.028] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2006] [Revised: 08/09/2006] [Accepted: 10/08/2006] [Indexed: 11/21/2022]
Abstract
Soymilk fermented with 3 selected Lactobacillus acidophilus strains were stored at various temperatures (-80 degrees C, 4 degrees C, 25 degrees C and 37 degrees C) for 8 weeks and the concentration of isoflavones determined weekly using RP-HPLC. The decreasing concentration of isoflavones in soymilk during storage due to degradation was found to fit the first order kinetics model. Isoflavone aglycones as well as isoflavone glucosides largely appeared to be stable during storage (P<0.01). Interestingly, the aglycone forms showed much smaller degradation as compared to glucoside forms at all the storage temperatures studied. Of the isoflavone aglycones, daidzein was found to be the most stable followed by genistein, while glycitein was least stable. Isoflavone aglycones such as glycitein, daidzein and genistein showed smaller degradation constants in fermented soymilk at lower storage temperatures (-80 degrees C and 4 degrees C) and higher degradation constants at higher storage temperatures (25 degrees C and 37 degrees C) with each strain. In contrast, glucosides glycitin and daidzin showed higher degradation at lower storage temperatures (-80 degrees C and 4 degrees C) and lower degradation at higher storage temperatures (25 degrees C and 37 degrees C). Storage temperature was therefore found to be very important in regulating the rate of degradation soy isoflavones in fermented soymilk.
Collapse
Affiliation(s)
- D O Otieno
- School of Molecular Sciences, Victoria University, Werribee Campus, P.O. Box 14428, Melbourne, Victoria 8001, Australia
| | | | | |
Collapse
|
10
|
Otieno DO, Schmidt MWT, Adiku S, Tenhunen J. Physiological and morphological responses to water stress in two Acacia species from contrasting habitats. Tree Physiol 2005; 25:361-71. [PMID: 15631984 DOI: 10.1093/treephys/25.3.361] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/13/2023]
Abstract
Container-grown seedlings of Acacia tortilis Forsk. Hayne and A. xanthophloea Benth. were watered either every other day (well watered) or every 7 days (water-stressed) for 1 year in a greenhouse. Total plant dry mass (T(dm)), carbon allocation and water relations were measured monthly. Differences in leaf area (LA) accounted for differences in T(dm) between the species, and between well-watered and water-stressed plants. Reduction in LA as a result of water stress was attributed to reduced leaf initiation, leaf growth rate and leaf size. When subjected to prolonged water stress, Acacia xanthophloea wilted more rapidly than A. tortilis and, unlike A. tortilis, lost both leaves and branches. These differences between species were attributed to differences in the allocation of carbon between leaves and roots and in the ability to adjust osmotically. Rapid recovery in A. xanthophloea following the prolonged water-stress treatment was attributed to high cell wall elasticity. Previous exposure to water stress contributed to water-stress resistance and improved recovery after stress.
Collapse
Affiliation(s)
- D O Otieno
- Department of Plant Ecology, University of Bayreuth, P.O. Box 95440, Bayreuth, Germany.
| | | | | | | |
Collapse
|