Redo pancreaticojejunal anastomosis for late-onset complete pancreaticocutaneous fistula after pancreaticojejunostomy.

BACKGROUND: Pancreaticojejunal (PJ) anastomosis occasionally fails several months after pancreaticoduodenectomy (PD) with Child reconstruction and can ultimately result in a late-onset complete pancreaticocutaneous fistula (Lc-PF). Since the remnant pancreas is an isolated segment, surgical intervention is necessary to create internal drainage for the pancreatic juice; however, surgery at the previous PJ anastomosis site is technically challenging even for experienced surgeons. Here we describe a simple surgical procedure for Lc-PF, termed redo PJ anastomosis, which was developed at our facility.  METHODS: Between January 2008 and December 2020, six consecutive patients with Lc-PF after PD underwent a redo PJ anastomosis, and the short- and long-term clinical outcomes have been evaluated. The abdominal cavity is carefully dissected through a 10-cm midline skin incision, and the PJ anastomosis site is identified using a percutaneous drain through the fistula tract as a guide, along with the main pancreatic duct (MPD) stump on the pancreatic stump. Next, the pancreatic stump is deliberately immobilized from the dorsal plane to prevent injury to the underlying major vessels. After fixing a stent tube to both the MPD and the Roux-limb using two-sided purse-string sutures, the redo PJ anastomosis is completed using single-layer interrupted sutures. Full-thickness pancreatic sutures are deliberately avoided by passing the needle through only two-thirds of the anterior side of the pancreatic stump. RESULTS: The redo PJ anastomosis was performed without any intraoperative complications in all cases. The median intraoperative bleeding and operative time were 71 (range 10-137) mL and 123 (range 56-175) min, respectively. Even though a new mild pancreatic fistula developed postoperatively in all cases, it could be conservatively treated within 3 weeks, and no other postoperative complications were recorded. During the median follow-up period of 92 (range 12-112) months, no complications at the redo PJ anastomosis site were observed. CONCLUSIONS: This research shows that the redo PJ anastomosis for Lc-PF we developed is a safe, feasible, and technically no demanding procedure with acceptable short- and long-term clinical outcomes. This procedure has the potential to become the preferred treatment strategy for Lc-PF after PD.

Full-scale application of a down-flow hanging sponge reactor combined with a primary sedimentation basin for domestic sewage treatment.

The down-flow hanging sponge (DHS) reactor is advantageous for sewage treatment since it produces an effluent quality that complies with the standards for reuse and there is little excess sludge. A full-scale DHS module was efficiently employed for the treatment of domestic sewage (200 m3 day-1) flowing from a primary sedimentation basin (PSB), which was used to reduce the suspended solids loading rate and enhance the oxidation of organics by heterotrophs. The combined PSB-DHS was successfully operated at a total hydraulic retention time of 3.4 h (2.4 h for PSB and 1.0 h for DHS) for the relatively long period of 600 days at sewage temperatures of 10 °C to 32 °C. The PSB-DHS consistently produced an effluent quality with minimum values of chemical oxygen demand, biochemical oxygen demand, and suspended solids of 59 ± 15, 12 ± 3.0, and 15 ± 7 mg L-1, respectively. The proposed system performed exceptionally well at removing organics and particulate matter over a short hydraulic retention time.

Sequence-Specific Capture of Oligonucleotide Probes (SCOPE): a Simple and Rapid Microbial rRNA Quantification Method Using a Molecular Weight Cutoff Membrane.

A method named sequence-specific capture of oligonucleotide probes (SCOPE) was developed for quantification of microbial rRNA molecules in a multiplex manner. In this method, a molecular weight cutoff membrane (MWCOM) was used for the separation of fluorescence-labeled oligonucleotide probes hybridized with rRNA from free unhybridized probes. To demonstrate proof of concept, probes targeting bacteria or archaea at different taxonomic levels were prepared and were hybridized with rRNAs. The hybridization stringency was controlled by adjusting reaction temperature and urea concentration in the mixture. Then, the mixture was filtered through the MWCOM. The rRNA and hybridized probes collected on the MWCOM were recovered and quantified using a spectrophotometer and fluorospectrometer, respectively. The method showed high accuracy in detecting specific microbial rRNA in a defined nucleic acid mixture. Furthermore, the method was capable of simultaneous detection and quantification of multiple target rRNAs in a sample with sensitivity up to a single-base mismatch. The SCOPE method was tested and benchmarked against reverse transcription-quantitative PCR (RT-qPCR) for the quantification of Bacteria, Archaea, and some key methanogens in anaerobic sludge samples. It was observed that the SCOPE method produced more reliable and coherent results. Thus, the SCOPE method allows simple and rapid detection and quantification of target microbial rRNAs for environmental microbial population analysis without any need for enzymatic reactions. IMPORTANCE Microorganisms play integral roles in the Earth's ecosystem. Microbial populations and their activities significantly affect the global nutrient cycles. Quantification of key microorganisms provides important information that is required to understand their roles in the environment. Sequence-based analysis of microbial population is a powerful tool, but it provides information only on relative abundance of microorganisms. Hence, the development of a simpler and quick method for the quantification of microorganisms is necessary. To address the shortcomings of a variety of molecular methods reported so far, we developed a simple, rapid, accurate, and multiplexed microbial rRNA quantification method to evaluate the abundance of specific microbial populations in complex ecosystems. This method demonstrated high specificity, reproducibility, and applicability to such samples. The method is useful for quantitative detection of particular microbial members in the environment.

Defining microbial community composition and seasonal variation in a sewage treatment plant in India using a down-flow hanging sponge reactor.

The characteristics of the microbial community in a practical-scale down-flow hanging sponge (DHS) reactor, high in organic matter and sulfate ion concentration, and the seasonal variation of the microbial community composition were investigated. Microorganisms related to sulfur oxidation and reduction (2-27%), as well as Leucobacter (7.50%), were abundant in the reactor. Anaerobic bacteria (27-38% in the first layer) were also in abundance and were found to contribute to the removal of organic matter from the sewage in the reactor. By comparing the Simpson index, the abundance-based coverage estimator (ACE) index, and the species composition of the microbial community across seasons (summer/dry, summer/rainy, autumn/dry, and winter/dry), the microbial community was found to change in composition only during the winter season. In addition to the estimation of seasonal variation, the difference in the microbial community composition along the axes of the DHS reactor was investigated for the first time. Although the abundance of each bacterial species differed along both axes of the reactor, the change of the community composition in the reactor was found to be greater along the vertical axis than the horizontal axis of the DHS reactor.

Characterization of sludge properties for sewage treatment in a practical-scale down-flow hanging sponge reactor: oxygen consumption and removal of organic matter, ammonium, and sulfur.

The characteristics of sludge retained in a down-flow hanging sponge reactor were investigated to provide a better understanding of the sewage treatment process in the reactor. The organic removal and sulfur oxidation conditions were found to differ between the first layer and the following three layers. It was found that 63% and 59% of the organic matter was removed in the first layer, even though the hydraulic retention time was only 0.2 h. It is thought that the organic removal resulted from aerobic and anaerobic biodegradation on the sponge medium. The sulfate concentration increased 1.5-1.9-fold in the first layer, with almost no subsequent change in the second to fourth layers. It was shown that oxidation of sulfide in the influent was completed in the first layer. The result of the oxygen uptake rate test with an ammonium nitrogen substrate suggested that the ammonium oxidation rate was affected by the condition of dissolved oxygen (DO) or oxidation-reduction potential (ORP).

The use of transureteroureterostomy during ureteral reconstruction for advanced primary or recurrent pelvic malignancy in the era of multimodal therapy.

PURPOSE: Cancerous involvement of a ureter is sometimes encountered in pelvic surgery for malignancy. We usually perform transureteroureterostomy (TUU) in cases of unilateral lower ureteral cancerous involvement. We report the outcomes in patients treated with TUU in our institute. METHODS: We retrospectively reviewed the medical records of 11 patients who underwent TUU between June 2006 and September 2015. RESULTS: The primary disease was colon cancer in five patients, rectal cancer in four, and uterine cervical cancer and ovarian cancer in one patient each. Early postoperative complications relevant to TUU occurred in four patients; however, three patients were managed conservatively and recovered quickly. Only one patient developed ureteral obstruction, which resulted from anastomotic hematoma. Follow-up periods ranged from 5 to 78 months with a median of 28 months. The median estimated glomerular filtration rate before and after TUU was 59 ml/min (range, 31-90 ml/min) and 62.0 ml/min (range, 43-127 mL/min), respectively. No patients experienced worsening of their renal function or recurrent urinary tract infection. CONCLUSIONS: Short-term outcomes are good and long-term renal function is maintained following TUU. TUU is considered a feasible technique for ureteral reconstruction for pelvic malignancy, and TUU has great potential in the era of multimodal therapy.

New laparoscopic procedure for left-sided pancreatic cancer-artery-first approach laparoscopic RAMPS using 3D technique.

BACKGROUND: For left-sided pancreatic ductal adenocarcinoma (PDAC), radical antegrade modular pancreatosplenectomy (RAMPS) is a reasonable surgical approach for tumor-free margin resection and systemic lymph node clearance. In pancreaticoduodenectomy for PDAC, the superior mesenteric artery (SMA)-first approach (or the "artery-first approach") has become the standard procedure. With improvements in laparoscopic instruments and techniques, some surgeons attempted to apply laparoscopic RAMPS (L-RAMPS) for carefully selected patients with left-sided PDAC. However, owing to several technical difficulties in this procedure, its application remains uncommon. Moreover, the artery-first approach in L-RAMPS has not been reported. Here, we developed the artery-first approach L-RAMPS for left-sided PDAC and have presented the same in this report. CASE PRESENTATION: Between June 2014 and July 2015, 16 patients with left-sided PDAC were referred to our division for pancreatic resection. The following technique was used for performing L-RAMPS on 3 of the 16 patients (19%). Six trocars were placed. After opening the omental bursa, only the middle segment of the pancreas was initially separated from both the left renal vein and the SMA. We termed this procedure as the "artery-first approach using a dome-shaped dorsomedial dissection (3D) technique." This 3D technique enabled the interruption of the entire arterial supply to the specimen while preserving the venous drainage through the splenic vein for preventing venous congestion. The technique also contributed to the early detection of no tumor infiltration into the SMA and the early determination of posterior dissection plane. After pancreatic neck transection, the splenic artery and vein were divided. Finally, the pancreatic tail and spleen were dissected in a right-to-left direction. All operations were completed without any intraoperative complications. The median blood loss and retrieved lymph node count were 75 mL and 37, respectively, which were superior to those reported by other previous studies on L-RAMPS. All resection margins were free of carcinoma. No severe postoperative complications were observed. CONCLUSIONS: The artery-first approach L-RAMPS using 3D technique is safe and feasible to perform. The significance of our proposed procedure is minimal blood loss and precise lymphadenectomy. Therefore, this novel technique may become the preferred treatment for left-sided PDAC in selected cases.

Liver necrosis shortly after pancreaticoduodenectomy with resection of the replaced left hepatic artery.

BACKGROUND: Surgeons, in general, underestimate the replaced left hepatic artery (rLHA) that arises from the left gastric artery (LGA), compared with the replaced right hepatic artery (rRHA), especially in standard gastric cancer surgery. During pancreaticoduodenectomy (PD), preservation of the rRHA arising from the superior mesenteric artery (SMA) is widely accepted to prevent critical postoperative complications, such as liver necrosis, bile duct ischemia, and biliary anastomotic leakage. In contrast, details of complication onset following rLHA resection remain unknown. We report two cases of postoperative liver necrosis shortly after rLHA resection during PD for advanced gastric cancer. CASE PRESENTATION: Both cases had advanced gastric cancer with infiltration of the pancreatic head. In case 1, the rLHA comprised segment 2/3 artery (A2 + A3), which arose from the LGA. The rRHA originated from the SMA, and the segment 4 artery (A4) was a branch of the rRHA. We conducted PD with combined en bloc resection of both the rLHA and rRHA, and anastomosis between the distal and proximal stumps of the rRHA and LGA, respectively. The divided A2 + A3 was not reconstructed. In case 2, the rLHA comprised segment 2 artery (A2) only, which arose from the LGA. The segment 3/4 artery and the RHAs originated from the proper hepatic artery. We undertook PD with combined en bloc resection of A2 without vascular reconstruction. In both patients, serious necrosis of the lateral segment of the liver occurred within 6 days after PD. Case 1 recovered with conservative management, whereas case 2 required lateral segmentectomy of the liver. Pathologically, the necrotic area in case 2 was apparently circumscribed and confined to segment 2 of the liver, potentially implicating rLHA resection during PD as causing hepatic necrosis. CONCLUSIONS: During PD, rLHA resection can cause serious liver necrosis. Therefore, this artery should be preserved as far as oncologically acceptable. In cases that require rLHA resection during PD due to tumor conditions, surgeons should carefully monitor postoperative course while keeping in mind the possible necessity of urgent hepatectomy.

Gene Expression Analysis of the Effect of Ischemic Infarction in Whole Blood.

Given the abundance of stroke patients and deaths from stroke worldwide, many studies concerning the aftermath of stroke are being carried out. To reveal the precise effect of ischemic infarction, we conducted a comprehensive gene expression analysis. Alongside a middle cerebral artery occlusion (MCAO) Sprague-Dawley rat model, we used a group undergoing sham surgery for comparison, which was the same as MCAO surgery but without blood vessel occlusion. Subsequently, infarction of the brains of MCAO-treated rats occurred, but did not occur in the sham-treated rats. Using whole blood, we carried out DNA microarray analysis, revealing the gene expression alterations caused by stroke. Downregulation of immune pathways and cluster of differentiation (CD) molecules indicated immunodepression. By conducting miRNA microarray analysis, we extracted seven miRNAs as significantly regulated: miR-107-5p, miR-383-5p, miR-24-1-5p, mir-191b, miR-196b-5p, and miR-3552 were upregulated, and mir-194-1 was downregulated. Among these seven miRNAs, three had one target mRNA each that was extracted as differentially expressed, and the expression levels of all pairs were inversely correlated. This indicates the occurrence of miRNA-mRNA regulatory systems in blood: between miR-107-5p and H2A histone family member Z (H2afz), miR-196b-5p and protein tyrosine phosphatase receptor type C (Ptprc), and miR-3552 and serine/arginine-rich splicing factor 2 (Srsf2). Moreover, six miRNAs had matching human miRNAs with similar sequences, which are potential human stroke biomarkers.

Proliferation of functional human natural killer cells with anti-HIV-1 activity in NOD/SCID/Jak3(null) mice.

Natural killer cells, a critical component of the innate immune system, eradicate both virus-infected cells and tumor cells through cytotoxicity and secretion of cytokines. Human NK cell research has largely been based on in vitro studies because of the lack of appropriate animal models. In this study, a selective proliferation model of functional human NK cells was established in NOD/SCID/Jak3(null) (NOJ) mice transplanted with peripheral blood mononuclear cells (PBMC) and K562 cells. The antiviral effects of NK cells were evaluated by challenging this mouse model with HIV-1. The percentage of intracellular p24(+) T cells and the amount of plasma p24 was decreased compared with NOJ mice transplanted with PBMC. Our findings indicate that NK cells have an anti-HIV-1 effect through direct cytotoxicity against HIV-1-infected cells. These mice provide an important model for evaluating human NK function against human infectious diseases such as HIV-1 and malignancies.

Clinical efficacy of liver resection after downsizing systemic chemotherapy for initially unresectable liver metastases.

BACKGROUND: This study sought to clarify the clinical benefits of liver resection after downsizing systemic chemotherapy for initially unresectable colorectal liver metastases (CLM). METHODS: Survival and clinical characteristics of CLM patients who underwent resection between January 2001 and December 2013 were retrospectively assessed. The study cohort of 88 patients with limited liver disease who underwent curative liver resection comprised 34 with initially resectable synchronous disease (synchronous group), 38 with initially resectable metachronous disease (metachronous group), and 16 with initially unresectable converted disease (conversion group). RESULTS: The median duration of follow-up for the overall study population was 33 (1-98) months. Overall survival (OS) in the conversion group was not significantly different from that in the other groups. However, disease-free survival (DFS) in the conversion group was significantly shorter than that in the synchronous group. The median DFS was 19.1 months in the synchronous group, 16.6 months in the metachronous group, and 15.3 months in the conversion group. Most patients in the conversion group had recurrence shortly after liver resection in the remnant liver with or without metastases at other sites, but many could undergo repeat hepatectomy or resection of the metastases at other sites. CONCLUSIONS: Although the converted patients tended to have recurrence shortly after liver resection, survival could be prolonged by repeat hepatectomy or resection of metastases at other sites. Liver resection after downsizing chemotherapy appears to be efficacious for patients with initially unresectable CLM and may result in long-term outcomes equivalent to those of patients with initially resectable CLM.

Evaluation of the resilience of a full-scale down-flow hanging sponge reactor to long-term outages at a sewage treatment plant in India.

Resilience to process outages is an essential requirement for sustainable wastewater treatment systems in developing countries. In this study, we evaluated the ability of a full-scale down-flow hanging sponge (DHS) reactor to recover after a 10-day outage. The DHS tested in this study uses polyurethane sponge as packing material. This full-scale DHS reactor has been tested over a period of about 4 years in India with a flow rate of 500 m(3)/day. Water was not supplied to the DHS reactor that was subjected to the 10-day outage; however, the biomass did not dry out because the sponge was able to retain enough water. Soon after the reactor was restarted, a small quantity of biomass, amounting to only 0.1% of the total retained biomass, was eluted. The DHS effluent achieved satisfactory removal of suspended solids, chemical oxygen demand, and ammonium nitrogen within 90, 45, and 90 min, respectively. Conversely, fecal coliforms in the DHS effluent did not reach satisfactory levels within 540 min; instead, the normal levels of fecal coliforms were achieved within 3 days. Overall, the tests demonstrated that the DHS reactor was sufficiently robust to withstand long-term outages and achieved steady state soon after restart. This reinforces the suitability of this technology for developing countries.

Recovery of partial nitrification in a down-flow hanging sponge reactor by salt shock loading.

Partial nitrification of ammonium-containing artificial wastewater was achieved using a down-flow hanging sponge (DHS) reactor with a hydraulic retention time (HRT) of 2 h by adjusting the influent salinity to 25 g Cl L(-1) with NaCl. The effect of HRT on partial nitrification was examined by varying HRT from 1 to 4 h. Extending HRT from 2 to 4 h had the effect of decreasing nitrite production and increasing nitrates. Since partial nitrification was not completely recovered after returning the HRT to 2 h, we examined the effect of salt shock loading on the recovery of partial nitrification. Salt shock loading with 150 gCl L(-1) for 72 h resulted in the fraction of NO2-N to total inorganic nitrogen in the effluent reaching 83.0% as much as 83 days after returning the salinity to the original level. Thus, despite the time required for the restoration of partial nitrification, the effectiveness of salt shock loading to achieve this aim was verified.

Laparoscopic Total Gastrectomy for Remnant Gastric Cancer Following Distal Gastrectomy with Radical Lymphadenectomy.

BACKGROUND/AIMS: In cases of remnantgastric cancer (RGC) with previous lymphadenectomy, laparoscopic total gastrectomy (LTG) is still uncommon because of the technical difficulties associated with adhesions from previous gastric cancer surgery and variations in anastomotic reconstruction. Here we demonstrate our procedure of LTG for RGC following distal gastrectomy (DG) with radical lymphadenectomy and review its clinical results. METHODOLOGY: From October 2008 to June 2014, we carried out three consecutive LTGs for RGC with previous lymphadenectomy. All cases had a past history of primary gastric cancer that had required open or laparoscopic DG with D2 radical lymphadenectomy. The preoperative TNM statuses of RGC were all cT1N0M0. RESULTS: All patients successfully underwent LTG without open conversion or intraoperative complications. The median operative duration was 360 min; the median blood loss was 45 mL. The median number of retrieved lymph nodes was 23. No complications occurred postoperatively, and the median length of postoperative hospitalization was 20 days. The pathological TNM statuses of the RGC were all T1N0M0. Resection margins were negative in all cases (R0). CONCLUSIONS: Our novel procedure of LTG for RGC following DG with radical lymphadenectomy is technically acceptable, safe, and feasible.

Protection of biomass from snail overgrazing in a trickling filter using sponge media as a biomass carrier: down-flow hanging sponge system.

This study investigated down-flow hanging sponge (DHS) technology as a promising trickling filter (TF) using sponge media as a biomass carrier with an emphasis on protection of the biomass against macrofauna overgrazing. A pilot-scale DHS reactor fed with low-strength municipal sewage was operated under ambient temperature conditions for 1 year at a sewage treatment plant in Bangkok, Thailand. The results showed that snails (macrofauna) were present on the surface of the sponge media, but could not enter into it, because the sponge media with smaller pores physically protected the biomass from the snails. As a result, the sponge media maintained a dense biomass, with an average value of 22.3 gVSS/L sponge (58.1 gTSS/L sponge) on day 370. The snails could graze biomass on the surface of the sponge media. The DHS reactor process performance was also successful. The DHS reactor requires neither chemical treatments nor specific operations such as flooding for snail control. Overall, the results of this study indicate that the DHS reactor is able to protect biomass from snail overgrazing.

A modified overlap method using a linear stapler for intracorporeal esophagojejunostomy after laparoscopic total gastrectomy.

BACKGROUND/AIMS: Intracorporeal esophagojejunostomy represents the most difficult step during laparoscopic total gastrectomy (LTG). A novel technique for intracorporeal esophagojejunostomy was recently developed and named the "overlap method." However, this procedure is thought to have some technical disadvantages. To facilitate intracorporeal esophagojejunostomy, we developed some modifications for the overlap method. METHODOLOGY: From October 2009 to July 2013, 63 consecutive patients with gastric cancer underwent LTG at our institution. Our modified overlap method was used for 54 patients with the following modifications. First, the esophagus was transected while being rotated by approximately 90 degrees in the clockwise direction. Second, an endoscopic linear stapler was used through the right lower trocar to create a side-to-side esophagojejunostomy. Third, the entry hole of the linear stapler was closed with intracorporeal hand-sewn continuous suturing. This procedure was termed the "modified overlap method." RESULTS: In 53 patients with the exception of one case, the modified overlap method was successfully completed (98.1%). Only one patient developed esophagojejunal anastomotic leakage (1.9%), which recovered well with conservative management. No postoperative anastomotic stricture or bleeding occurred. CONCLUSIONS: Our modified overlap method for intracorporeal esophagojejunostomy provides amazingly satisfactory outcomes. We believe this procedure could become a standard method for intracorporeal esophagojejunostomy after LTG.

Efficient transduction of 11 poly-arginine peptide in an ischemic lesion of mouse brain.

Direct intracellular delivery of intact proteins has been successfully achieved by tagging cell-penetrating peptide (CPP), which consists of short positively charged amino acids, such as 11 poly-arginine (11R); however, in vivo delivery of the proteins to the brain has remained challenging because it is unclear whether CPP would enable proteins to cross the blood-brain barrier (BBB). In this study, we conducted an in vivo kinetic study to investigate the efficiency of 11R-mediated peptide delivery in the normal and ischemic brain. The 11R was observed in the microvessels and neurons surrounding the microvessels throughout the brain 1 hour after systemic administration, but the signal of the peptide was faint after 2 hours. In a transient middle cerebral artery occlusion mouse model, 11R was markedly enhanced and remained detectable in the cells on the ipsilateral side for as long as 8 hours after administration compared with the contralateral side. These results suggest that 11R is capable of in vivo delivery to the brain by passing through the BBB. Furthermore, 11R-mediated protein transduction could be used for the delivery of therapeutic molecules in cerebral ischemia.

A novel integrated approach to quantitatively evaluate the efficiency of extracellular polymeric substances (EPS) extraction process.

A novel integrated approach is developed to quantitatively evaluate the extracellular polymeric substances (EPS) extraction efficiency after taking into account EPS yield, EPS damage, and cell lysis. This approach incorporates grey relational analysis and fuzzy logic analysis, in which the evaluation procedure is established on the basis of grey relational coefficients generation, membership functions construction, and fuzzy rules description. The flocculation activity and DNA content of EPS are chosen as the two evaluation responses. To verify the feasibility and effectiveness of this integrated approach, EPS from Bacillus megaterium TF10 are extracted using five different extraction methods, and their extraction efficiencies are evaluated as one real case study. Based on the evaluation results, the maximal extraction grades and corresponding optimal extraction times of the five extraction methods are ordered as EDTA, 10 h > formaldehyde + NaOH, 60 min > heating, 120 min > ultrasonication, 30 min > H2SO4, 30 min > control. The proposed approach here offers an effective tool to select appropriate EPS extraction methods and determine the optimal extraction conditions.

Characterization of sulfide-oxidizing microbial mats developed inside a full-scale anaerobic digester employing biological desulfurization.

The microbial mats responsible for biological desulfurization from biogas in a full-scale anaerobic digester were characterized in terms of their structure, as well as their chemical and microbial properties. Filament-shaped elemental sulfur 100-500 µm in length was shown to cover the mats, which cover the entire headspace of the digester. This is the first report on filamentous sulfur production in a non-marine environment. The results of the analysis of the mats suggest that the key players in the sulfide oxidation and sulfur production in the bio-desulfurization in the headspace of the digester were likely to be two sulfide-oxidizing bacteria (SOB) species related to Halothiobacillus neapolitanus and Sulfurimonas denitrificans, and that the microbial community, cell density, activity for sulfide oxidation varied according to the environmental conditions at the various locations of the mats. Since the water and nutrients necessary for the SOB were provided by the digested sludge droplets deposited on the mats, and our results show that a higher rate of sulfide oxidation occurred with more frequent digested sludge deposition, the habitat of the SOB needs to be made in the lower part of the headspace near the liquid level of the digested sludge to maintain optimal conditions.