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The generation of surplus sludge during biological wastewater treatment has become a prevalent issue, necessitating the development of a dewatering approach that is efficient, economically feasible, and ecologically sound. Bdellovibrio-and-like-organisms (BALOs) are obligatory parasitic bacteria that prey on an array of bacteria. In this study, different BALO strains were isolated and purified from waste activited sludge (WAS). Anti-predation host strains were applied to screen the BALO strains with different host-range to minimize the overlap of the biolysis prey spectrum. In addition, the BALO strains with different host preferences were mixed for sludge biolysis treatment efficiency comparison. The results indicated that the capillary suction time and the bound water content in the WAS treated with the mixed BALOs were significantly decreased by 25.9% ± 1.7% and 5.2% ± 1.2%, respectively, compared to those treated with the single BALO strain. The soluble chemical oxygen demand concentration in the mixed BALOs treated group was increased by 31.2% ± 0.7% than that treated with the single strain. The findings indicate that the mixed strains used in the treatment process resulted in a notable enhancement of both sludge dewatering performance and lysis degree. In addition, the abundance of Proteobacteria treated with the BALO mixtures decreased by 69.1% than the single strain treated one which demonstrated that the BALO mixture expanded the sludge host lysis spectrum. This study revealed the different effects of single and mixed strains on sludge community structure, suggesting that the BALO host-range expansion is crucial to further improve sludge dewatering performances. [ABSTRACT FROM AUTHOR]

[Display omitted] • The sediments after oxidation with nitrate show well phosphorus adsorption effect. • Fe-P is the main speciation of phosphorus immobilization in the oxidizing sediment. • Higher sediment oxidation correlates with improved phosphorus immobilization. • Biological phosphorus immobilization is potential pathway in oxidation sediment. During remediation of black-odorous sediment, the pathways of phosphorus immobilization require clarification alongside the oxidation of sulfide and ferrous. This study separated the oxidation stages of sulfide and ferrous through controlled sodium nitrate dosing ratios and methods, and analyzed the changes in phosphorus species and immobilization effects throughout these processes. Results showed that iron-bound phosphorus was the primary contributor to the phosphorus immobilization in the oxidation process, with increased 19% in ferrous oxidation stage and affected the transformation between phosphorus sources or sinks in the adsorption experiment. Additionally, the increase in abundance of phosphorus uptake and transport genes, and denitrifying phosphorus accumulation genes in sediment after ferrous oxidation (1 %–18 % and 87 %–164 %, respectively) indicated the potential for biological phosphorus immobilization. These results demonstrated that higher degrees of sediment oxidation correlate with stronger phosphorus immobilization capacities, providing theoretical bases for phosphorus immobilization during the restoration of black-odorous water bodies. [ABSTRACT FROM AUTHOR]

Anionic and cationic surfactants are very common pollutants which could be biodegraded by microorganisms during the biological step of the Wastewater Treatment Plant (WWTP) process. During the biodegradation step, the microorganisms use the surfactant as as a source of nutrients breaking down their chemical structure into simpler chemical compounds. There have been data showing that certain surfactants can be completely biodegraded to CO2 and H2O, but there have been also data suggesting that some surfactants were extremely low biodegradable. Their low biodegradability could reside on surfactants negative effects on water's surface, such as reducing air/water oxygen transfer, lowering the water quality by foam introduction and sorption on solid particles which generate a toxic effect on microorganisms. For these reasons it is necessary to determine the individual biodegradability of each surfactant or each class of surfactants. In this study, we investigate de biodegradability potential of cationic and anionic surfactants and subsequently their effect on microorganisms. The cationic surfactants, quaternary ammonium salts are molecules with at least one long hydrophobic alkyl chain attached to a positively charged nitrogen atom. The properties of the cationic surfactants linked to surface activity, adsorption onto negatively charged solids, biocidal activity, and their reaction with anionic surfactants made them desirable for a large number of applications such as fabric softeners, disinfectants, demulsifies, emulsifiers, wetting agents, and processing aids. Unfortunately, quaternary ammonium salts can harm organisms from the aquatic systems. Alkyl sulfate and alkyl benzenesulfonate are two of the main anionic surfactants used and sold in high amounts because of their wide range utility in different fields such as personal care products, petrochemical production and foaming production. The excessively presence of cationic and anionic surfactants in the environment generates concern due the pollution effects on the ecosystems by affecting both aquatic systems (marine ecosystems and freshwater ecosystems). The study of their biodegradation potential was carried out for 28 days and the results showed a partial biodegradation of surfactants induced by the microbiological community from the activated WWTP sludge. [ABSTRACT FROM AUTHOR]

Due to limited land availability in municipal wastewater treatment plants, integrated fixed-film activated sludge (IFAS) technology offers significant advantages in improving nitrogen removal performance and treatment capacity. In this study, two systems, IFAS and Anaerobic-Anoxic-Oxic Activated sludge process (AAO), were compared by adjusting parameters such as hydraulic retention time (HRT), nitrifying solution recycle ratio, sludge recycle ratio, and dissolved oxygen (DO). The objective was to investigate pollutant removal capacity and differences in microbial community composition between the two systems. The study showed that, at an HRT of 12 h, the IFAS system exhibited an average increase of 5.76%, 8.85%, and 12.79% in COD, NH 4 +-N, and TN removal efficiency respectively, compared to the AAO system at an HRT of 16 h. The TP concentration in the IFAS system reached 0.82 mg/L without the use of additives. The IFAS system demonstrated superior effluent results under lower operating conditions of HRT, nitrification solution recycle ratio, and DO. The 16S rDNA analysis revealed higher abundance of denitrification-related associated flora, including Proteobacteria , Bacteroidetes , and Planctomycetota , in the IFAS system compared to the AAO system. Similarities were observed between microorganisms attached to the media and activated sludge in the anaerobic, anoxic, and oxic tanks. q-PCR analysis indicated that the incorporation of filler material in the IFAS system resulted in similar abundance of nitrifying bacteria genes on the biofilm as in the oxic tank. Additionally, denitrifying genes showed higher levels due to aeration scouring and the presence of alternating aerobic-anaerobic environments on the biofilm surface, enhancing nitrogen removal efficiency. [Display omitted] • The experiments were conducted in a wastewater treatment plant. • The HRT of IFAS system was 4h shorter than that of AAO system. • The nitrification and denitrification capability of IFAS system is stronger than that of AAO system. • The microbial population of nitrifying and denitrifying in IFAS system is more abundant than that in AAO system. • There was a high abundance of genes related to nitrogen removal in the biofilm of IFAS system. [ABSTRACT FROM AUTHOR]

Samples of (I) produced waters, (II) central processing facility (CPF) waters and (III) pipeline solids were collected from a light oil-producing field. The biocide, tetrakis(hydroxymethyl)phosphonium sulfate (THPS) was routinely used in the CPF. Samples monitoring indicated that THPS was effective in microbial control but also increased concentrations of sulfate and phosphate in transitioning from Type I to Type II waters. Type II waters had high concentrations (up to 60 mM) of acetate but low most probable numbers (MPNs) of acid-producing and sulfate-reducing bacteria, indicating the presence of active biocide, as high MPNs were found in Type I waters. Solids had high phosphate and high MPNs, indicating that THPS was inactive. Solids had oil and an anaerobic community dominated by Acetobacterium, which may contribute to conversion of oil to acetate. The presence of THPS prevented the use of this acetate in Type II waters, where it accumulated to unusually high concentrations. [ABSTRACT FROM AUTHOR]

This study investigated the performance of co-digesting cucumber residues, corn stover, and pig manure at different ratios. Microbial community structure was analyzed to elucidate functional microorganism contributing to methane production during co-digestion. Results show that mixing cucumber residues with pig manure and corn stover could significantly improved methane yields 1.27–3.46 times higher than mono-feedstock. The methane yields decreased with the cucumber residues increasing when the pig manure ratio was fixed at 4 and 3, and was opposite at ratio 5. The optimal mixture ratio was T2 with the highest methane yield (305.4 mL/g VS) and co-digestion performance index (1.97). The main microbiological community in T2 was bacteria of Firmicutes (44.6%), Bacteroidetes (32.5%), Synergistetes (3.8%) and archaea of Methanosaeta (37.1%), Methanospirillum (18.2%). The mixture ratios changed the microbial community structures. The adding proportion of cucumber residues changed the community composition of the archaea, especially the proportion of Methanosaeta . [ABSTRACT FROM AUTHOR]

Foxtail millet (Setaria italica L.) is an important alternative crop plant that is cultivated in Northern China. To explore its forage-use potential, a feeding trial of 60 healthy male feedlotting lambs weighing 23 ± 0.36 kg was conducted to determine the effects of replacing peanut vine hay (PVH) with different ratios (0%, 20%, 60%, and100%) of foxtail millet silage (FMS) as forage in rations on growth performance, nutrient digestibility, rumen fermentation characteristics, and bacterial community. The feeding trial was completed in two stages (Stage 1: days 1–42, forage: concentrate = 25:75; Stage 2: days 43–84, forage: concentrate = 20:80). The results show that dry matter intake (DMI) and average daily gain (ADG) increased linearly with the inclusion level of FMS in the diet (P < 0.05). Increasing the FMS replacement of PVH in rations quadratically increased the nutrient digestibility of dry matter, organic matter, crude protein and ether extract (P < 0.01) during the two stages, but the improvement of neutral detergent fiber (NDF) in response to FMS inclusion was observed during stage 2 (P < 0.01) instead of stage 1. Increasing the forage inclusion level of FMS linearly increased the digestibility of acid detergent fiber (ADF) at two stages (P < 0.05). Regarding rumen fermentation characteristics, increasing the FMS replacement of PVH in rations decreased rumen pH and linearly increased microbial crude protein (MCP) for the two stages (P < 0.05) and linearly increased NH 3 -N and total volatile fatty acid (VFA) (P < 0.05) during stage 2 instead of stage 1. Regarding rumen VFA pattern, increasing the FMS replacement of PVH in rations increased molar propionate proportion and remarkably decreased the acetate: proportion ratio after lamb feeding, suggesting that rumen fermentation shifted to glucogenic propionate production. Furthermore, the rumen contents of each treatment were subjected to high-throughput sequencing analysis of 16 S rRNA genes in the V3-V4 hypervariable region; here, increasing the FMS replacement of PVH in the rations did not change the alpha diversity indexes, except for the Simpson index, including Chao1, ACE, and OTUs in rumen, while increasing the FMS level in the rations linearly increased the Simpson index (P < 0.01). Increasing the FMS replacement of PVH in the rations did not alter the relative abundance of the major bacteria phyla, nor most of the major genera of rumen in lambs, except for an increasing trend in Proteobacteria. Increasing the FMS replacement of PVH in rations numerically increased starch hydrolysis bacteria, including Prevotella (P = 0.06) and Selenomonas (P = 0.05), while it linearly decreased fiber hydrolysis bacteria involved Ruminococcus and unclassified_Ruminococcaceae (P < 0.05), with numerical improvement occurring in unclassified_Lachnospiraceae (P = 0.11) in the rumen. In brief, increasing the FMS replacement of PVH in rations exhibited greater feed efficiency with increased nutrient digestibility, promoting the total VFA production as available energy in the rumen of feedlotting lambs. Rumen fermentation shifted toward glucogenic propionate production in response to dietary FMS inclusion, and this shift was found to be associated with the increased growth abundance of Prevotella and Selenomonas and the inhibition of Ruminococcus in the rumen. • The palatability of foxtail millet silage is better than that of peanut vine hay. • Foxtail millet silage improved the growth performance and feed efficiency. • Foxtail millet silage replacement of peanut vine hay in rations increased utilization of fermentable energy. • Foxtail millet silage influenced the compositions of the ruminal bacterial community in the genus. [ABSTRACT FROM AUTHOR]

Routine evaluation of the slaughter process is performed by the enumeration of the aerobic colony count, Enterobacteriaceae and Salmonella spp. on the carcass through destructive or non-destructive methods. With non-destructive methods, bacteria are counted from a minimum area of 100 cm2 in different sampling sites on the pork carcasses, and the results of these investigated areas are pooled to one value for the complete carcass evaluation (a total of 400 cm2). However, the composition of the bacterial community present on the different sampling areas remains unknown. The aim of the study was to characterize the microbial population present on four areas (ham, back, jowl and belly) of eight pork carcasses belonging to two different slaughterhouses through culture-dependent (Matrix-assisted laser desorption/ionization time-of-flight Mass Spectrometry MALDI-TOF MS, combined with 16S rRNA gene sequencing) and complementary culture-independent (16S rRNA amplicon sequencing) methods. The presence of Salmonella spp. and Y. enterocolitica was additionally assessed. Using MALDI-TOF MS, Staphylococcus , Pseudomonas , and Escherichia coli were found to dominate the bacterial cultures isolated from the 8 carcasses. Based on the 16S rRNA amplicon sequencing analyses however, no specific genus clearly dominated the bacterial community composition. By using this culture-independent method, the most abundant genera in microbial populations of the ham, back, jowl and belly were found to be similar, but important differences between the two slaughterhouses were observed. Thus, present data suggests that the indigenous bacterial population of individual animals is overruled by the microbial population of the slaughterhouse in which the carcass is handled. Also, our data suggests that sampling of only one carcass area by official authorities may be appropriate for the evaluation of the hygienic status of the carcasses and therefore of the slaughter process. • Contamination levels on four pork carcass areas were not significant different. • Bacterial communities on the four carcasses areas were dominated by the same genera. • Sampling only one area is appropriate for the evaluation of the slaughter's hygiene. • Microbial communities on the carcasses were distinct between the two slaughterhouses. • Bacterial community on the carcass is influenced by the slaughterhouse community. [ABSTRACT FROM AUTHOR]