Nowaki Hijikata

Polyphosphate has a central role in the rapid and massive accumulation of phosphorus in extraradical mycelium of an arbuscular mycorrhizal fungus

Title Polyphosphate has a central role in the rapid and massive accumulation of phosphorus in extraradical mycelium of an arbuscular mycorrhizal fungus Author(s) Hijikata, Nowaki; Murase, Masatake; Tani, Chiharu; Ohtomo, Ryo; Osaki, Mitsuru; Ezawa, Tatsuhiro Citation New Phytologist, 186(2), 285-289 https://doi.org/10.1111/j.1469-8137.2009.03168.x Issue Date 2010 Doc URL http://hdl.handle.net/2115/48540 Type article (author version) File Information Hijikata_et_al_HUS.pdf

Polyphosphate accumulation is driven by transcriptome alterations that lead to near-synchronous and near-equivalent uptake of inorganic cations in an arbuscular mycorrhizal fungus

Arbuscular mycorrhizal (AM) fungi accumulate a massive amount of phosphate as polyphosphate to deliver to the host, but the underlying physiological and molecular mechanisms have yet to be elucidated. In the present study, the dynamics of cationic components during polyphosphate accumulation were investigated in conjunction with transcriptome analysis. Rhizophagus sp. HR1 was grown with Lotus japonicus under phosphorus-deficient conditions, and extraradical mycelia were harvested after phosphate application at prescribed intervals. Levels of polyphosphate, inorganic cations and amino acids were measured, and RNA-Seq was performed on the Illumina platform. Phosphate application triggered not only polyphosphate accumulation but also near-synchronous and near-equivalent uptake of Na(+) , K(+) , Ca(2+) and Mg(2+) , whereas no distinct changes in the levels of amino acids were observed. During polyphosphate accumulation, the genes responsible for mineral uptake, phosphate and nitrogen metabolism and the maintenance of cellular homeostasis were up-regulated. The results suggest that inorganic cations play a major role in neutralizing the negative charge of polyphosphate, and these processes are achieved by the orchestrated regulation of gene expression. Our findings provide, for the first time, a global picture of the cellular response to increased phosphate availability, which is the initial process of nutrient delivery in the associations.

Enhanced Valine Production in Corynebacterium glutamicum with Defective H+-ATPase and C-Terminal Truncated Acetohydroxyacid Synthase

We have reported increased glutamate production by a mutant of Corynebacterium glutamicum ATCC14067 (strain F172-8) with reduced H+-ATPase activity under biotin-limiting culture conditions (Aoki et al. Biosci. Biotechnol. Biochem., 69, 1466–1472 (2005)). In the present study, we examined valine production by an H+-ATPase-defective mutant of C. glutamicum. Using the double-crossover chromosome replacement technique, we constructed a newly defined H+-ATPase-defective mutant from ATCC13032. After transforming the new strain (A-1) with a C-terminal truncation of acetohydroxyacid synthase gene (ilvBN), valine production increased from 21.7 mM for the wild-type strain to 46.7 mM for the A-1 in shaking flask cultures with 555 mM glucose. Increased production of the valine intermediate acetoin was also observed in A-1, and was reduced by inserting acetohydroxyacid isomeroreductase gene (ilvC) into the ilvBN plasmid. After transformation with this new construct, valine production increased from 38.3 mM for the wild-type strain to 95.7 mM for A-1 strain. To the best of our knowledge, this is the first report indicating that an H+-ATPase-defective mutant of C. glutamicum is capable of valine production. Our combined results with glutamate and valine suggest that the H+-ATPase defect is also effective in the fermentative production of other practical compounds.

Aquaporin-mediated long-distance polyphosphate translocation directed towards the host in arbuscular mycorrhizal symbiosis: application of virus-induced gene silencing.

Arbuscular mycorrhizal fungi translocate polyphosphate through hyphae over a long distance to deliver to the host. More than three decades ago, suppression of host transpiration was found to decelerate phosphate delivery of the fungal symbiont, leading us to hypothesize that transpiration provides a primary driving force for polyphosphate translocation, probably via creating hyphal water flow in which fungal aquaporin(s) may be involved. The impact of transpiration suppression on polyphosphate translocation through hyphae of Rhizophagus clarus was evaluated. An aquaporin gene expressed in intraradical mycelia was characterized and knocked down by virus-induced gene silencing to investigate the involvement of the gene in polyphosphate translocation. Rhizophagus clarus aquaporin 3 (RcAQP3) that was most highly expressed in intraradical mycelia encodes an aquaglyceroporin responsible for water transport across the plasma membrane. Knockdown of RcAQP3 as well as the suppression of host transpiration decelerated polyphosphate translocation in proportion to the levels of knockdown and suppression, respectively. These results provide the first insight into the mechanism underlying long-distance polyphosphate translocation in mycorrhizal associations at the molecular level, in which host transpiration and the fungal aquaporin play key roles. A hypothetical model of the translocation is proposed for further elucidation of the mechanism.

Inactivation mechanisms of pathogenic bacteria in several matrixes during the composting process in a composting toilet

This study aimed to compare the inactivation rate and the mechanisms of pathogenic bacteria in three matrixes (sawdust, rice husk and charcoal) during the composting process. The inactivation rate was evaluated with Escherichia coli strain and the damaged parts and/or functions were evaluated with three different media. Normalized inactivation rate constant in three media and from three matrixes had no significant difference in each process (pure, 1 month and 2 months). The value in rice husk was relatively increased during 2 months but there was no significant difference. The inactivation rate constants of Tryptic Soy Agar (TSA) and Compact Dry E. coli/Coliform in pure sawdust and rice husk were relatively lower than that of Desoxycholate Agar, but increased in 2 months. This indicated that damaging part was changed from outer membrane to enzymes and metabolisms during the 2-month composting process. In the case of charcoal, only the TSA value in a pure matrix was relatively lower than that of others, but it increased in 2 months. This indicated that damaging part was changed from outer membrane and enzyme to metabolisms during the composting process. Composting matrix and composting process did not significantly affect inactivation rate of pathogenic bacteria during the process but affected the damaging part of the bacteria.

Suitability of biochar as a matrix for improving the performance of composting toilets.

To evaluate the suitability of biochar (rice husk charcoal) as a matrix in composting toilets that can decompose human faeces and recover fertiliser components, the composting process during toilet operation and the agricultural value of the resulting compost were characterised by performing a comparison with sawdust, rice husks, and corn stalks. The faecal decomposition ratio in biochar was 42%, similar to the values for rice husks (46%) and corn stalks (41%), but higher than the value for sawdust (25%). Heterotroph micro-organism acidity is qualitatively higher in biochar than in sawdust. However, nitrogen loss in biochar was 19%, lower than that in rice husks (36%) and corn stalks (25%), but similar to that in sawdust (16%). Although the biochar compost had no significant impact on the cation exchange capacity and water retention of sandy soil, the ratio of nitrogen transportation into plants was 12.8%, higher than that for the other materials. These results suggest that biochar is effective for achieving high faecal decomposition, low nitrogen loss, and high nutrient supply.

Removal and Deactivation of Intestinal Parasites in Aerobic Mesophilic Composting Reactor for Urine Diverting Composting Toilet

ABSTRACT. Urine diverting composting toilets are becoming increasingly popular and are promoted to sanitize human excreta for recycling them into fertilizer. This study aimed to assess the removal and deactivation of intestinal parasites during the composting process. Batch experiments were conducted by composting human feces in an aerobic composting reactor using shea nut shells as bulky matrix. During 60 composting days, the removal of helminthes eggs and protozoa cysts was assessed and compared with the removal of indicator bacteria and pathogenic bacteria. The bacteria were analyzed by the single layer method on selective media and parasites were counted directly by microscope after compost preparation. The viability of helminthes eggs and protozoan cysts was assessed by a staining exclusion dyeing method. At low temperature, desiccation and alkaline pH obtained during the composting process could not completely destroy indicator bacteria while Salmonella sp. was eliminated after 30 composting days. Entamoeba hystolitica cysts were present in feces at a higher concentration (854/g mean) than Ascaris lumbricoides eggs (204/g mean). The composting process had reduced the total number of Ascaris eggs after 35 days while Entamoeba cysts were still present (beyond 54/g cysts) after 60 composting days. There were no viable Ascaris eggs after 30 days while the viability of Entamoeba cysts was still up 31%. In high concentration, Entamoeba cysts had survived stronger than Ascaris eggs during the composting process. Because of the persistence of some pathogens in compost both Ascaris eggs and Entamoeba cysts are good indicators for parasite removal.

Grey water treatment by the slanted soil system with unsorted soil media

This study evaluated the performance of unsorted soil media in the slanted soil treatment system, in terms of removal efficiency in suspended solids (SS), chemical oxygen demand (COD), linear alkylbenzene sulphonate (LAS) and Escherichia coli, and lifetime until clogging occurs. Unsorted soil performed longer lifetime until clogging than sorted fine soil. Removal of SS, COD, and LAS also performed same or better level in unsorted soil than fine soil. As reaction coefficients of COD and LAS were described as a function of the hydraulic loading rate, we can design a slanted soil system according to the expected hydraulic loading rate and the targeted level of COD or LAS in effluent. Regarding bacteria removal, unsorted soil performed sufficient reduction of E. coli for 5 weeks; however, the removal process occurred throughout all four chambers, while that of fine soil occurred in one to two chambers.

The Concept of Resources Oriented Agro-Sanitation System and Its Business Model

This chapter proposes concept of the sanitation business model, based on the discussions; what is necessary to solve current world’s sanitation issue and what is the limitation of current sanitation concept. Proposed policy was on the basis of the Postmodern Sanitation concept; (1) discuss a sanitation value chain which create and add a value to human excreta and its products, and build a sanitation business model to drive this sanitation value chain, (2) design the sanitation business model focusing on incentive for individual toilet users, (3) analyze current user’s value chain to find available potential resources, (4) connect these potential sanitation resources to next value chain, (5) make a financial plan based on market analysis of sanitation product, (6) find and organize facilitating organization to support individual toilet users’ business. This concept was applied for the case of rural area in Burkina Faso, and reasonable agro-sanitation business model was designed based on material flow analysis and value flow analysis.

Slanted Soil System

Slanted soil system is low cost, simple system suitable for greywater treatment. Performance of the slanted soil system for greywater was evaluated in light of required water quality for irrigation reuse. Removal rate of COD and BDOC, those may cause clogging of irrigation facility, was 52–83% and 88–89%, respectively. LAS, one of the major surfactants, was removed more than 80%. Phytotoxic test showed that more than 2.82 m treatment is required. Only fine soil (1–4 mm) performed 5 log10 and 3 log10 reductions of Escherichia coli and MS2 phage, while coarse soil could not remove those pathogens. Clogging was observed in fine soil after 3–5 weeks operation; however, combination of coarse soil chamber and fine soil chamber could extend it to 8 weeks, without decrease of treatment performance. Reductions of total COD and LAS were described by first-order reaction model, and reaction coefficient k was described by equation of per area discharged rate.