Application of autothermal thermophilic aerobic digestion as a sustainable recycling process of organic liquid waste: Recent advances and prospects.

Autothermal thermophilic aerobic digestion (ATAD) has been used to stabilize organic waste since the 1960s and is considered sustainable technology. ATAD has several advantages, including high biodegradation efficiency, pathogen inactivation, and ease of operation. Although ATAD research has a long history, the number of studies on ATAD is much lower than those on similar aerobic processes, particularly composting. Previous review articles addressed the origin, design, operational experiences, metabolism, and the microorganisms at the thermophilic stage of ATAD. This article reviews the digestion systems, applications, and characteristics of ATAD; compares system performance and microbial community structure of ATAD with those of other biological processes such as composting, activated sludge, and anaerobic digestion; and discusses the physicochemical properties and factors of ATAD. The challenges, opportunities, and prospects for the application of ATAD are also discussed. This review suggests that ATAD is feasible for treating organic liquid waste (1-6% total solid content) in small-sized towns and can help establish a sustainable society.

Clarification of the Dynamic Autothermal Thermophilic Aerobic Digestion Process Using Metagenomic Analysis.

This study details a unique process of autothermal thermophilic aerobic digestion (ATAD) of human excreta useful in producing nitrogen-rich and pathogen-free organic fertilizer. The process was divided into initial, middle, and final phases, based on changes in temperature, dissolved oxygen (DO), and bacterial community structure. The aim of this study was to determine bacterial factors that would affect liquid fertilizer production in the process, using shotgun metagenomic analysis of each phase. Although the abundances of all 28 gene categories include 4 categories in SEED subsystems level 1 were similar to those in another type of wastewater treatment system, the abundances of 4 gene categories changed remarkably. Among them, a decrease in the abundance of the phage-related gene category and the presence of antibacterial substances in secondary metabolism may explain the change in bacterial community structure from the material to the initial phase. Increases in the abundances of two gene categories, phage-related and secondary metabolism, coincided with a decrease in alpha diversity from the material to the initial phase. A potential increase in the abundance of genes in the category of sporulation from the middle to the final phase was correlated with deterioration of growth conditions and stabilization processes. In addition, prompt consumption of short-chain fatty acids in the initial phase and unusually stable ammonia accumulation throughout the process could be explained by the presence/absence of related metabolic genes. In conclusion, the relationships between bacterial function and unique characteristics of ATAD were revealed; our findings support the enhancement of liquid fertilizer production from wastewater. IMPORTANCE Metagenome analysis was performed to determine the microbial dynamics of the unique autothermal thermophilic aerobic digestion process of human excreta, which includes initial, middle, and final phases. In this study, we revealed the details of functional genes related to physicochemical and bacterial characteristics in the ATAD process. Four gene categories showed increases and decreases during the digestion process. In addition, the unusual stable accumulation of ammonia and prompt consumption of short-chain fatty acids were explained by the absence or presence of related metabolic genes. In addition to revealing the relationships between bacteria and physicochemical properties, the results of this research may support improving wastewater management systems worldwide by using the ATAD process in liquid fertilizer production systems.

Lab-scale autothermal thermophilic aerobic digestion can maintain and remove nitrogen by controlling shear stress and oxygen supply system.

Autothermal thermophilic aerobic digestion (ATAD) is used to treat human excreta hygienically. We previously reported a unique full-scale ATAD, showing distinctive bacterial community transitions and producing high-nitrogen-content liquid fertilizer; nevertheless, the mechanism remains unclear. One hypothesis involves using a gas-inducing (GI) agitator. We designed a lab-scale GI system and compared it with a disk-turbine (DT) agitator system by mimicking the temperature shift of full-scale ATAD. The agitation system and its agitation speed greatly affected physicochemical properties and bacterial community structure. GI system at 1000 rpm (GI1000; high total carbon removal efficiency, 88.3%), with few nitrifying and denitrifying bacteria, maintained a high ammoniacal nitrogen concentration and had more shared operational taxonomic units related to Acinetobacter sp., Arcobacter sp., and Longimicrobium sp. with the full-scale ATAD compared with the GI system at 490 rpm and DT system at 1000 rpm (DT1000). Furthermore, DT1000, with a high abundance of nitrifying and denitrifying bacteria such as Alcaligenes aquatilis and Pseudomonas caeni, removed 94.7% total nitrogen with 71.9% total carbon removal efficiency. These results suggested that shear stress and oxygen supply system would change the bacterial community structure, thus affected ATAD performances. Consequently, it is possible that ATAD can be applied for not only production of highly nitrogen-containing liquid fertilizer but also extremely nitrogen removal of wastewater.

Development of a simultaneous identification method for 13 animal species using two multiplex real-time PCR assays and melting curve analysis.

We developed a simple and rapid method for animal species identification in the forensic science field based on mitochondrial DNA using two multiplex real-time PCRs and analysis of the resultant SYBR Green I melting curves. This method was designed to identify nine domestic animals simultaneously (dog, cat, rabbit, cattle, pig, chicken, goat, sheep and horse) and four wild animals (deer, raccoon-dog, monkey and bear) by comparing the different melting temperatures of the amplicons produced from samples originating from each species. For this analysis, we targeted various mitochondrial genes, including those encoding cytochrome b (cytb), NADH dehydrogenase 5 (ND5), cytochrome c oxidase 3 (COX3), tRNA-ND5, and tRNA-ATP synthase 8 (ATP8). For practical applications, this study presents a validation of this assay including its specificity, sensitivity and robustness. The limits of detection in the multiplex reactions were 10 pg for eight of the nine animals, excluding horse (1 pg for horse). The method was able to correctly identify the animal species from artificial forensic samples including blood stains, saliva, hair and bone, and samples digested in artificial gastric fluid, and for 17 forensic casework samples. The data from the multiplex real-time PCR assays are obtainable only 30 min after DNA extraction of the samples, making the assays useful for screening samples containing DNA from unknown animal origin in the forensic field.

A dibenzoylmethane derivative inhibits lipopolysaccharide-induced NO production in mouse microglial cell line BV-2.

Microglial activation has been suggested to play important roles in various neurodegenerative diseases by phagocytosis and producing various factors such as nitric oxide (NO), proinflammatory cytokines. Excessive production of NO, as a consequence of increased inducible nitric oxide synthase (iNOS) in microglia, contributes to the neurodegeneration. During a search for compounds that regulate endoplasmic reticulum (ER) stress, a dibenzoylmethane derivative, 2,2'-dimethoxydibenzoylmethane (DBM 14-26) was identified as a novel neuroprotective agent (Takano et al., Am. J. Physiol. Cell Physiol. 293, C1884-1894, 2007). We previously reported in cultured astrocytes that DBM 14-26 protected hydrogen peroxide-induced cell death and inhibited lipopolysaccharide (LPS)-induced NO production (Takano et al., J. Neurosci. Res. 89, 955-965, 2011). In the present study, we assessed the effects of DBM 14-26 on microglia using the mouse cell line BV-2 and found that DBM 14-26 inhibited LPS-induced iNOS expression and NO production also in microglia. DBM 14-26 also suppressed LPS-induced IL-1ß expression. Conditioned medium of BV-2 cells stimulated by LPS significantly decreased cell viability of neuron (human neuroblastoma SH-SY5Y cells) compared with the absence of LPS. Conditioned medium of BV-2 cells stimulated by LPS in the presence of DBM 14-26 did not significantly decreased cell viability of neuron. These results indicate that microglial activation by LPS causes neuronal cell death and DBM 14-26 protect neuron through the inhibition of microglial activation. Functional regulation of microglia by DBM 14-26 could be a therapeutic candidate for the treatment of neurodegenerative diseases.

Pyrosequencing analysis of microbial community and food-borne bacteria on restaurant cutting boards collected in Seri Kembangan, Malaysia, and their correlation with grades of food premises.

This study adopts the pyrosequencing technique to identify bacteria present on 26 kitchen cutting boards collected from different grades of food premises around Seri Kembangan, a city in Malaysia. Pyrosequencing generated 452,401 of total reads of OTUs with an average of 1.4×10(7) bacterial cells/cm(2). Proteobacteria, Firmicutes and Bacteroides were identified as the most abundant phyla in the samples. Taxonomic richness was generally high with >1000 operational taxonomic units (OTUs) observed across all samples. The highest appearance frequencies (100%) were OTUs closely related to Enterobacter sp., Enterobacter aerogenes, Pseudomonas sp. and Pseudomonas putida. Several OTUs were identified most closely related to known food-borne pathogens, including Bacillus cereus, Cronobacter sakazaki, Cronobacter turisensis, Escherichia coli, E. coli O157:H7, Hafnia alvei, Kurthia gibsonii, Salmonella bongori, Salmonella enterica, Salmonella paratyphi, Salmonella tyhpi, Salmonella typhimurium and Yersinia enterocolitica ranging from 0.005% to 0.68% relative abundance. The condition and grade of the food premises on a three point cleanliness scale did not correlate with the bacterial abundance and type. Regardless of the status and grades, all food premises have the same likelihood to introduce food-borne bacteria from cutting boards to their foods and must always prioritize the correct food handling procedure in order to avoid unwanted outbreak of food-borne illnesses.

Antimicrobial susceptibilities of Propionibacterium acnes isolated from patients with acne vulgaris.

Antibiotic susceptibilities of Propionibacterium acnes in Japan were determined. Erythromycin-resistance was found in 10.4% (5/48) of the strains, and four of these were cross-resistance to clindamycin. Although the erythromycin ribosome methylase gene erm(X) was looked for, no strain carrying erm(X) was found. Sequencing analysis revealed that all of the erythromycin-resistant strains had a mutation in the peptidyl transferase region of the 23S rRNA gene: G2057A, A2058G, or A2059G. Consequently, our results show that P. acnes resistance to macrolides is caused by a mutation in the 23S rRNA gene, and has been increasing in Japan.