Shorter Lag Phase Research Articles

Exploiting tropical fruit processing coproducts as circular resources to promote the growth and maintain the culturability and functionality of probiotic lactobacilli

This study evaluated the use of acerola (Malpighia glabra L., CACE), cashew (Anacardium occidentale L., CCAS), and guava (Psidium guayaba L., CGUA) fruit processing coproducts as substrates to promote the growth, metabolite production, and maintenance of the viability/metabolic activity of the probiotics Lactobacillus acidophilus LA-05 and Lacticaseibacillus paracasei L-10 during cultivation, freeze-drying, storage, and exposure to simulated gastrointestinal digestion. Probiotic lactobacilli presented high viable counts (≥8.8 log colony-forming units (CFU)/mL) and a short lag phase during 24 h of cultivation in CACE, CCAS, and CGUA. Cultivation of probiotic lactobacilli in fruit coproducts promoted sugar consumption, medium acidification, and production of organic acids over time, besides increasing the of several phenolic compounds and antioxidant activity. Probiotic lactobacilli cultivated in fruit coproducts had increased survival percentages after freeze-drying and during 120 days of refrigerated storage. Moreover, probiotic lactobacilli cultivated and freeze-dried in fruit coproducts had larger subpopulations of live and metabolically active cells when exposed to simulated gastrointestinal digestion. The results showed that fruit coproducts not only improved the growth and helped to maintain the viability and metabolic activity of probiotic strains but also enriched the final fermented products with bioactive compounds, being an innovative circular strategy for producing high-quality probiotic cultures.

High potential lignocellulose-degrading microbial seed exploration from various biogas plants for methane production

Converting lignocellulosic materials into renewable energy through anaerobic digestion (AD) often has low degradation efficiency and thus needs improvement. Inoculum seeds from biogas plants fed with cow manure (CM), pig manure (PM), Napier grass (NG), and goat manure (GM) were explored for high-potential lignocellulose-degrading inocula based on the biochemical methane potential. Overall, CM, PM, and GM seeds could degrade lignocellulose. However, PM inoculum exhibited the highest CH4 production rate from cellulose powder, xylan, and Napier grass degradation by 46.32, 49.61, and 18.56 NmL/gVSadded·d, indicating the shortest lag phase but lagged behind GM and CM for alkali lignin. Microbial community analysis revealed lignocellulose-degrading microorganisms in the inocula. A high relative abundance of cellulose-degrading bacteria, such as Anaerolineaceae, Romboutsia, Bacteroidetes vadinHA17, and Clostridium sensu stricto 1, was detected. Anaerobic lignin-degrading bacteria were found in CM, PM, and GM inocula. Moreover, Bathyarchaeia from the archaeal group involved in lignocellulose degradation was found in CM and GM inocula. Keystone methanogens for methanogenesis were also detected in all inocula. PM inoculum possesses a promising inoculum seed for shortening the start-up period of the lignocellulose-degrading reactor with high AD performance and stability as it provides a short lag time and a high rate of methanogenesis.

Amyloid-like Aggregation of Wheat Gluten and Its Components during Cooking: Mechanisms and Structural Characterization.

Amyloid-like aggregation widely occurs during the processing and production of natural proteins, with evidence indicating its presence following the thermal processing of wheat gluten. However, significant gaps remain in understanding the underlying fibrillation mechanisms and structural polymorphisms. In this study, the amyloid-like aggregation behavior of wheat gluten and its components (glutenin and gliadin) during cooking was systematically analyzed through physicochemical assessment and structural characterization. The presence of amyloid-like fibrils (AFs) was confirmed using X-ray diffraction and Congo red staining, while Thioflavin T fluorescence revealed different patterns and rates of AFs growth among wheat gluten, glutenin, and gliadin. AFs in gliadin exhibited linear growth curves, while those in gluten and glutenin showed S-shaped curves, with the shortest lag phase and fastest growth rate (t1/2 = 2.11 min) observed in glutenin. Molecular weight analyses revealed AFs primarily in the 10-15 kDa range, shifting to higher weights over time. Glutenin-derived AFs had the smallest ζ-potential value (-19.5 mV) and the most significant size increase post cooking (approximately 400 nm). AFs in gluten involve interchain reorganization, hydrophobic interactions, and conformational transitions, leading to additional cross β-sheets. Atomic force microscopy depicted varying fibril structures during cooking, notably longer, taller, and stiffer AFs from glutenin.

Characterization of MLST-99 Salmonella Typhimurium and the monophasic variant I:4,[5],12:i:- isolated from Canadian Atlantic coast shellfish.

Salmonella enterica subsp. enterica Typhimurium and its monophasic variant I 1;4,[5],12:i:- (MVST) are responsible for thousands of reported cases of salmonellosis each year in Canada, and countries worldwide. We investigated S. Typhimurium and MVST isolates recovered from raw shellfish harvested in Atlantic Canada by the Canadian Food Inspection Agency (CFIA) over the past decade, to assess the potential impact of these isolates on human illness and to explore possible routes of shellfish contamination. Whole-genome sequence analysis was performed on 210 isolates of S. Typhimurium and MVST recovered from various food sources, including shellfish. The objective was to identify genetic markers linked to ST-99, a sequence type specifically associated with shellfish, which could explain their high prevalence in shellfish. We also investigated the genetic similarity amongst CFIA ST-99 isolates recovered in different years and geographical locations. Finally, the study aimed to enhance the molecular serotyping of ST-99 isolates, as they are serologically classified as MVST but are frequently misidentified as S. Typhimurium through sequence analysis. To ensure recovery of ST-99 from shellfish was not due to favourable growth kinetics, we measured the growth rates of these isolates relative to other Salmonella and determined that ST-99 did not have a faster growth rate and/or shorter lag phase than other Salmonella evaluated. The CFIA ST-99 isolates from shellfish were highly clonal, with up to 81 high-quality single nucleotide variants amongst isolates. ST-99 isolates both within the CFIA collection and those isolated globally carried numerous unique deletions, insertions and mutations in genes, including some considered important for virulence, such as gene deletions in the type VI secretion system. Interestingly, several of these genetic characteristics appear to be unique to North America. Most notably was a large genomic region showing a high prevalence in genomes from Canadian isolates compared to those from the USA. Although the functions of the majority of the proteins encoded within this region remain unknown, the genes umuC and umuD, known to be protective against UV light damage, were present. While this study did not specifically examine the effects of mutations and insertions, results indicate that these isolates may be adapted to survive in specific environments, such as ocean water, where wild birds and/or animals serve as the natural hosts. Our hypothesis is reinforced by a global phylogenetic analysis, which indicates that isolates obtained from North American shellfish and wild birds are infrequently connected to isolates from human sources. These findings suggest a distinct ecological niche for ST-99, potentially indicating their specialization and adaptation to non-human hosts and environments, such as oceanic habitats.

Exploring Rhodospirillum rubrum response to high doses of carbon monoxide under light and dark conditions

Environmental concerns about residues and the traditional disposal methods are driving the search for more environmentally conscious processes, such as pyrolysis and gasification. Their main final product is synthesis gas (syngas) composed of CO, CO2, H2, and methane. Syngas can be converted into various products using CO-tolerant microorganisms. Among them, Rhodospirillum rubrum is highlighted for its biotechnological potential. However, the extent to which high doses of CO affect its physiology is still opaque. For this reason, we have studied R. rubrum behavior under high levels of this gas (up to 2.5 bar), revealing a profound dependence on the presence or absence of light. In darkness, the key variable affected was the lag phase, where the highest levels of CO retarded growth to more than 20 days. Under light, R. rubrum ability to convert CO into CO2 and H2 depended on the presence of an additional carbon source, such as acetate. In those conditions where CO was completely exhausted, CO2 fixation was unblocked, leading to a diauxic growth. To enhance R. rubrum tolerance to CO in darkness, a UV-accelerated adaptive laboratory evolution (UVa-ALE) trial was conducted to isolate clones with shorter lag phases, resulting in the isolation of clones 1.4-2B and 1.7-2A. The adaptation of 1.4-2B was mainly based on mutated enzymes with a metabolic function, while 1.7-3A was mostly affected at regulatory genes, including the anti-repressor PpaA/AerR. Despite these mutations having slight effects on biomass and pigment levels, they successfully provoked a significant reduction in the lag phase (−50%).Keypoints• CO affects principally R. rubrum lag phase (darkness) and growth rate (light)• CO is converted to CO2/H2during acetate uptake and inhibits CO2fixation (light)• UVa-ALE clones showed a 50% reduction in the lag phase (darkness)Graphical

Optimization of biomethane production from lignocellulosic biomass by a developed microbial consortium

Biomethane production from lignocellulosic biomass via anaerobic digestion (AD) is a promising avenue for bioenergy. However, maximizing biomethane yield using developed microbial consortium (DMC) remains a complex challenge. This study aims to elucidate the comparative efficacy of a purposefully DMC under controlled conditions for AD of kallar grass (KG), rice husk (RH) and wheat residue (WR). The DMC encompasses Bacteroidetes, Firmicutes, Proteobacteria, Euryarchaeota, and Chloroflexi, with methanogens representing 14.6% of the community. Thorough physico-chemical characteristics and ultimate analyses provided comprehensive insights into compositions and bio-methane potentials prediction of biomasses. The digester revealed higher biomethane potentials (BMPs) with short lag phase and retention time and showed methane content of 61–64.6% during the first week of AD. The amount of volatile fatty acids (VFA) did not exceed the threshold levels, which facilitated the smooth operation of AD. The BMP was found highest in KG (289.7 mL/g VS), followed by RH (283.3 mL/g VS), and WR (269.7 mL/g VS) which is significantly higher than previously reported studies. The modified Gompertz model showed the best fit, followed by logistic and transference function models. The observed results signpost the tremendous potential of waste biomass particularly KG, RH and WR to produce biomethane by DMC. This study provides crucial insights for optimizing BMP emphasizing the promising prospects of KG, RH, and WR for sustainable bioenergy applications.

Co-digestion approach for enhancement of biogas production by mixture of untreated napier grass and industrial hydrolyzed food waste.

The co-digestion of untreated Napier grass (NG) and industrial hydrolyzed food waste (FW) was carried out in the batch reactor to investigate the effect of substrate ratios on biogas production performance. Two-stage anaerobic digestion was performed with an initial substrate concentration of 5g VSadded/L and a Food to Microorganism Ratio (F/M) of 0.84. The 1:1 ratio of the NG and FW showed the optimum performances on biogas production yield with a value of 1,161.33mL/g VSadded after 60 days of digestion. This was followed by the data on methane yield and concentration were 614.37mL/g VSadded and 67.29%, respectively. The results were similar to the simulation results using a modified Gompertz model, which had a higher potential methane production and maximum production rate, as well as a shorter lag phase and a coefficient of determination of 0.9945. These findings indicated that the co-digestion of Napier grass and hydrolyzed food waste can enhance biogas production in two-stage anaerobic digestion.

Adaptive laboratory evolution to obtain furfural tolerant Saccharomyces cerevisiae for bioethanol production and the underlying mechanism.

Furfural, a main inhibitor produced during pretreatment of lignocellulose, has shown inhibitory effects on S. cerevisiae. In the present study, new strains named 12-1 with enhanced resistance to furfural were obtained through adaptive laboratory evolution, which exhibited a shortened lag phase by 36 h, and an increased ethanol conversion rate by 6.67% under 4 g/L furfural. To further explore the mechanism of enhanced furfural tolerance, ADR1_1802 mutant was constructed by CRISPR/Cas9 technology, based on whole genome re-sequencing data. The results indicated that the time when ADR1_1802 begin to grow was shortened by 20 h compared with reference strain (S. cerevisiae CEN.PK113-5D) when furfural was 4 g/L. Additionally, the transcription levels of GRE2 and ADH6 in ADR1_ 1802 mutant were increased by 53.69 and 44.95%, respectively, according to real-time fluorescence quantitative PCR analysis. These findings suggest that the enhanced furfural tolerance of mutant is due to accelerated furfural degradation. Importance: Renewable carbon worldwide is vital to achieve "zero carbon" target. Bioethanol obtained from biomass is one of them. To make bioethanol price competitive to fossil fuel, higher ethanol yield is necessary, therefore, monosaccharide produced during biomass pretreatment should be effectively converted to ethanol by Saccharomyces cerevisiae. However, inhibitors formed by glucose or xylose oxidation could make ethanol yield lower. Thus, inhibitor tolerant Saccharomyces cerevisiae is important to this process. As one of the main component of pretreatment hydrolysate, furfural shows obvious impact on growth and ethanol production of Saccharomyces cerevisiae. To get furfural tolerant Saccharomyces cerevisiae and find the underlying mechanism, adaptive laboratory evolution and CRISPR/Cas9 technology were applied in the present study.

Effect of direct enzyme addition on the anaerobic digestion of OFMSW

The organic fraction of municipal solid waste (OFMSW) has high biodegradability and is a good feedstock for anaerobic digestion (AD). However, the solubilization of OFMSW is a limiting factor for AD. In this study, enzyme treatment was investigated to increase the conversion of complex materials of OFMSW into soluble fractions. Six different concentrations (0.15, 0.3, 0.5, 1.0, 1.5 and 3.0 mg/VSadded) of the alpha amylase enzyme (obtained from Aspergillus oryzae) were directly added as a powder and automated biochemical methane potential (BMP) tests were performed under thermophilic conditions. According to BMP tests, the methane (CH4) yield increased up to 17.5 % and the lag phase decreased to 19.3 % after enzyme addition. The highest CH4 yield and shortest lag phase were obtained when 0.5 mg of enzyme/VSadded was added to the reactor. These findings suggest that direct alpha amylase enzyme application obtained from Aspergillus oryzae can be used to increase biogas production by enhancing solubilization of OFMSW for AD.

Extracellular Matrix Deposition Defines the Duration of Cell Sheet Assembly from Human Adipose-Derived MSC

Cell sheet (CS) engineering using mesenchymal stromal cells (MSC) draws significant interest for regenerative medicine and this approach translates to clinical use for numerous indications. However, little is known of factors that define the timing of CS assembly from primary cultures. This aspect is important for planning CS delivery in autologous and allogeneic modes of use. We used a comparative in vitro approach with primary donors’ (n = 14) adipose-derived MSCs and evaluated the impact of healthy subject’s sex, MSC culture features (population doubling time and lag-phase), and extracellular matrix (ECM) composition along with factors related to connective tissue formations (α-SMA and FAP-α) on CS assembly duration. Using qualitative and quantitative analysis methods, we found that, in seeded MSCs, high contents of collagen I and collagen IV had a direct correlation with longer CS assembly duration. We found that short lag-phase cultures faster turned to a ready-to-use CS, while age, sex, fibronectin, laminin, α-SMA, and FAP-α failed to provide a significant correlation with the timing of assembly. In detachable CSs, FAP-α was negatively correlated with the duration of assembly, suggesting that its concentration rose over time and contributed to MSC activation, transitioning to α-SMA-positive myofibroblasts and ECM turnover. Preliminary data on cell density and collagen I deposition suggested that the TGF-β1 signaling axis is of pivotal importance for ECM composition and construct maturation.

Modulation of the Aromatic Profile of Verdejo Wine through Sequential Inoculation of Wickerhamomyces anomalus and Saccharomyces cerevisiae

Two strains of Saccharomyces cerevisiae (Sc01 and Sc02) and one strain of Wickerhamomyces anomalus (Wa) were isolated from organic Verdejo spontaneous fermentations and used for the development of experimental winemaking. Sc01 and Sc02 represented 52.7% of the population of the Saccharomyces strains isolated throughout the fermentation process. W. anomalus appeared as the predominant species among the non-Saccharomyces yeasts. Wa turned out to be the strain of this species with the shortest lag phase and positive enzymatic activities, and it was selected for white wine production. Fermentations with unique inoculation of S. cerevisiae strains were compared with sequential inoculation with W. anomalus. The results showed that the sequential inoculations did not affect the fermentation kinetics or physicochemical characteristics of the wines compared with the unique inoculations. However, this study identified a significant impact on the aromatic profiles of the produced wines due to the sequential inoculations. This modification resulted in a similar new aromatic profile in both sequential inoculations, demonstrating common characteristics related to the contribution of W. anomalus. In general, the sequential fermentations were mainly characterized by lower levels of acetate esters and an increase in ethyl acetate levels, whereas lower levels of ethyl octanoate and ethyl dec-9-enoate were detected. Propan-1-ol and butan-1-ol showed an increase in the sequential fermentations, while 4-methylpentan-1-ol and 2-phenylethanol were found in lower concentrations. These results highlight the great influence that the presence of specific strains of native non-Saccharomyces yeasts exerts on the characteristics of elaborate wines.

Endotoxin accelerates insulin amyloid formation and inactivates insulin signal transduction

Aims and objectivesThe aim of this study is to discuss the influence of endotoxin on insulin amyloid formation, to provide guidance for therapeutic insulin preparation and storage. Materials and methodsThe ThT and ANS binding assays were applied to characterize the dynamics curve of insulin amyloid formation with the presence or absence of endotoxin. The morphological structures of intermediate and mature insulin fibrils were observed with SEM and TEM. Secondary structural changes of insulin during fibriliation were examined with CD, FTIR and Raman spectral analysis. The cytotoxic effects of oligomeric and amyloidogenic insulin aggregates were detected using a cck-8 cell viability assay kit. The influence of endotoxin on insulin efficacy was analyzed by monitoring the activation of insulin signal transduction. Key findingsThT analysis showed that endotoxin, regardless of species, accelerated insulin fibrils formation in a dose-dependent manner, as observed with a shorter lag phase. ANS binding assay demonstrated endotoxin provoked the exposure of insulin hydrophobic patches. The results of SEM and TEM data displayed that endotoxin drove insulin to cluster into dense and viscous form, with thicker and stronger filaments. Based on CD, FTIR and Raman spectra, endotoxin promoted the transition of α-helix to random coil and β-strand secondary structures during insulin aggregation. Insulins in both oligomeric and amyloidogenic forms were cytotoxic to HepG2 cells, with the former being more severe. Finally, the efficacy of endotoxin treated insulin obviously decreased. SignificanceOur studies revealed that endotoxin disrupts the structural integrity of insulin and promotes its amyloidosis. These findings offered theoretical guidance for insulin storage and safe utilization, as well as pointing up a new direction for insulin resistance research.

Quantitative effect of adding percentages of anammox granules on the start-up process and microbial community analysis

The anaerobic ammonium oxidation (anammox) process is challenging due to its long start-up duration and high demand for mature anammox seed sludge. However, adding a small amount of anammox sludge to the inoculum can be a reasonable solution. This study investigated the effect of adding percentage of anammox granules (0, 1, 2, 4, and 8%) in the seed sludge on the anammox start-up process. The anammox process was achieved in all five reactors after 55, 6, 5, 3 and 0 days. Increasing the adding percentage effectively shortened the duration of lag phase and cell lysis, but had little effect on the final nitrogen removal performance, except for 4% adding percentage. Families of Brocadiaceae, Burkholderiaceae, Ignavibacteriaceae, SJA-28, and Rhodocyclaceae were dominant, with a core microbiota of eight operational taxonomic unites (OTUs), and Candidatus Brocadia fulgida became the dominant anammox species. Seven synergistic members with anammox bacteria were identified by correlation network analysis. Major potential functional groups involved in C and N cycle were also observed by FAPROTAX. Together with the qPCR and sequencing results, it was suggested that more than 2% of adding percentages would result in a short lag phase, rapid growth rate in elevation stage, high final performances, and anammox bacteria abundance comparable to that in the anammox seed sludge. This crucial finding indicated the feasibility of economical and rapid start-up of the anammox process with a minimum amount of anammox seed sludge.

Development of the Latanoprost Solid Delivery System Based on Poly(l-lactide-co-glycolide-co-trimethylene carbonate) with Shape Memory for Glaucoma Treatment

Latanoprost (LTP) is a prostaglandin F2α analog used to lower intraocular pressure in glaucoma treatment administered daily as eye drops. In this study, a universal model based on poly(l-lactide-co-glycolide-co-trimethylene carbonate) with shape memory was proposed for the development of a solid biodegradable formulation with prolonged release administered intraconjunctivally, intravitreally, subconjunctivally, and subcutaneously. Solution casting and electron beam (EB) irradiation were applied to the matrix formulation. The properties of the native matrix and matrices degraded in a PBS buffer (pH 7.4) were monitored by NMR, DSC, GPC, and SEM. Water uptake (WU) and weight loss (WL) were also analyzed. LTP was released over 113 days in a tri-phasic and sigmoidal pattern without a burst effect and with a relatively long second release phase, in which changes were observed in the glass transition temperature, molecular weight (Mn), WU, and WL. EB irradiation decreased the initial Mn, increased WU, and accelerated LTP release with a shortened lag phase. This provides the opportunity to partially eliminate the use of drops at the start of treatment. SEM observations indicated that surface erosion is the prevalent degradation mechanism. The proposed model is an interesting solution during a preliminary study to develop final medicinal products that provide high adherence.

781-P: Sustained-Release Formulation Development and Preclinical Evaluations of Monthly or Bimonthly Injectable Semaglutide and Tirzepatide

Objective: Accumulated real-world data indicates strong tendencies to develop long-acting formulating drug. This study aimed for optimization and preclinical development of the sustained-release formulation of Semaglutide (PT403) and Tirzepatide (PT404) to explore whether they are applicable for bi-monthly (once every two months) injectable drugs. Methods: Semaglutide or Tirzepatide dissolved in acetic acid with diverse combination of biodegradable PLGA polymers was applied to the ultrasonic spray dryer that produces API-encapsulated microspheres. The pharmacokinetic profiles of PT403 and PT404 were tested in rats and minipigs after a single subcutaneous injection. Results: Both optimized formulation of PT403 and PT404 have demonstrated favorable physicochemical properties, showing uniformly sized microspheres (20±3 μm). Furthermore, the aggregation issue of Semaglutide, which was not observed in PT404, was solved by applying PROW technology. Also, increased encapsulation rates and higher drug loading (~8%) showed higher bioavailability, no initial burst and a short lag phase (<3 days). Additionally, the release of PT403 initiated from 3 days to 70 days in minipigs, which potentially indicates every two months injectable (Q8W) in humans, compared to the once-a-weekly (QW) Semaglutide and Tirzepatide. Lastly, double injection of PT403 can easily reached the therapeutic window with 1.4 of the Peak-to-Through ratio, based on simulated PK profiles in repeated injection in human. Conclusion: Evidence from recent formulation studies of PT403 and PT404 indicates that Peptron's SmartDepot technology is strongly applicable for long-acting drugs. The comprehensive results of formulation development, preclinical data, and mass production will provide the basis for successful clinical development of PT403 and PT404 as monthly or bi-monthly injectable diabetes and obesity drugs. Disclosure J.Jung: None. S.Chang: None.

Development of efficient modules for recombinant protein expression and periplasmic localisation in Pseudomonas bharatica CSV86T

Escherichia coli has been widely employed as a host for heterologous protein expression. However, due to certain limitations, alternative hosts like Pseudomonas, Lactococcus and Bacillus are being explored. Pseudomonas bharatica CSV86T, a novel soil isolate, preferentially degrades wide range of aromatics over simple carbon sources like glucose and glycerol. Strain also possesses advantageous eco-physiological traits, making it an ideal host for engineering xenobiotic degradation pathways, which necessitates the development of heterologous expression systems. Based on the efficient growth, short lag-phase and rapid metabolism of naphthalene, Pnah and Psal promoters (regulated by NahR) were selected for expression. Pnah was found to be strong and leaky as compared to Psal, using 1-naphthol 2-hydroxylase (1NH, ∼66 kDa) as reporter gene in strain CSV86T. The Carbaryl hydrolase (CH, ∼72 kDa) from Pseudomonas sp. C5pp was expressed under Pnah in strain CSV86T and could successfully be translocated to the periplasm due to the presence of the Tmd + Sp sequence. The recombinant CH was purified from the periplasmic fraction and the kinetic characteristics were found to be similar to the native protein from strain C5pp. These results potentiate the suitability of P. bharatica CSV86T as a desirable host, while Pnah and the Tmd + Sp can be employed for overexpression and periplasmic localisation, respectively. Such tools find application in heterologous protein expression and metabolic engineering applications.

Development of a Primary Sewage Sludge Pretreatment Strategy Using a Combined Alkaline–Ultrasound Pretreatment for Enhancing Microbial Electrolysis Cell Performance

Ultrasound and combined alkaline–ultrasound pretreatment (AUP) strategies were examined for primary sewage sludge (SS) disintegration and were utilized to evaluate the degree of solubilization (DS). Further, the pretreated primary SS was operated in microbial electrolysis cells (MECs) to maximize methane production and thereby improve the reactor performance. The highest DS of 67.2% of primary SS was recorded with the AUP. MEC reactors operated with the AUP showed the highest methane production (240 ± 6.4 mL g VSin−1). VS (61.1%) and COD (72.2%) removal in the MEC ALK-US showed the best organic matter removal efficiency. In the modified Gompertz analysis, the substrate with the highest degree of solubilization (AUP) had the shortest lag phase (0.2 ± 0.1 d). This implies that forced hydrolysis via pretreatment could enhance biodegradability, thereby making it easy for microorganisms to consume and leading to improved MEC performances. Microbial analysis implicitly demonstrated that pretreatment expedited the growth of hydrolytic bacteria (Bacteroidetes and Firmicutes), and a syntrophic interaction with electroactive microorganisms (Smithella) and hydrogenotrophic methanogens (Methanoculleus) was enriched in the MECs with AUP sludge. This suggests that the AUP strategy could be useful to enhance anaerobic digestion performance and provide a new perspective on treating primary SS in an economical way.

Growth and Antibiotic Sensitivity Status of Bacillus spp. associated with Abalone (Haliotis asinina) as Probiotic Candidate Selection

The use of probiotics is an innovation in an effort to increase production and fight pathogens in aquaculture cultivation environments. Probiotic candidate microorganisms are selected selectively to ensure that the probiotics used are safe and provide benefits for the host and the environment. This study aims to select probiotic candidates based on the aspects of growth and sensitivity to antibiotics from 4 isolates of Bacillus from abalone (Haliotis asinina). Growth observations were carried out by turbidimetric method using a spectrophotometer at a wavelength of 600 nm in SWC media, and antibiotic sensitivity was tested using Rifampicin, Gentamicin, Kanamycin, and Erythromycin antibiotics using the well-diffusion agar method. The growth analysis of isolates was described by a growth curve based on the OD value, and antibiotic susceptibility based on the diameter of the inhibition zone. The results showed that the growth of the four isolates of Bacillus spp. had a short lag phase, ranging from 1-2 hours, an exponential phase ranging from 15 hours to B. pumilus SLK1 and B. licheniformis SLK2 isolates, and 12 hours to B. coagulans CaK1 and B. coagulans CaK6 isolates. Antibiotic sensitivity showed that B. coagulans CaK1 isolates were sensitive to all the tested antibiotics, while B. pumilus SLK1 isolates, B. licheniformis SLK2, and B. coagulans CaK6 were only sensitive to Rifampicin and Gentamicin antibiotics. The ideal probiotic candidate is an isolate with good growth and does not have resistance properties, based on the results of this study CaK1 isolate has the potential as a probiotic candidate

Microbial degradation of organochlorine pesticide: 2,4-Dichlorophenoxyacetic acid by axenic and mixed consortium

The presence of 2,4-dichlorophenoxyacetic acid (2,4-D), an organochlorine herbicide, in the environment has raised public concern as it poses hazard to both humans and the ecosystem. Three potential strains having the capability to degrade 2,4-D were isolated from on site agricultural soil and identified as Arthrobacter sp. SVMIICT25, Sphingomonas sp. SVMIICT11 and Stenotrophomonas sp. SVMIICT13. Over 12 days of incubation, 81–90% of 100 mg/L of 2,4-D degradation was observed at 2% inoculum. A shorter lag phase with 80% of degradation efficiency was observed within 5 days when the inoculum size was increased to 10%. Six microbial consortia were prepared by combining the isolates along with in-house strains, Bacillus sp. and Pseudomonas sp. Consortia R3 (Arthrobacter sp. + Sphingomonas sp.), operated with 10% of inoculum, showed 85–90% degradation within 4 days and 98–100% in 9 days. Further, targeted exo-metabolite analysis confirmed the presence and catabolism of intermediate 2,4-dichlorophenol and 4-chlorophenol compounds.

Key properties identification of biochar material in anaerobic digestion of sewage sludge for enhancement of methane production

Owing to the intricate physicochemical characteristics of biochar material, a comprehensive understanding of their effects and mechanisms involved in anaerobic digestion still needs to be explored. In this study, the methane yield of sludge hydrolysate was inhibited by 13.3% after the addition of granular activated carbon (GAC), which was due to the predominance of non-selective adsorption by GAC. Whereas the shortened lag phase time (38.2%), the improved methane production rate (16.6%), and the increased methane yield (7.6%) were achieved after the algal biochar (ABC) addition. The methanogenic improvements by ABC were attributed to its redox capacity other than pH buffering capacity. Quantitative results showed that the content of phenolic and lactonic groups were 4.8 and 2.3 times higher than that of GAC, respectively, which endowed ABC with a stronger redox capacity, especially electron-donating capacity. Surface oxygen-containing functional groups like phenolic and lactonic groups of biochar material should be valued for the improvement of anaerobic digestion. The findings of this study provided a comprehensive insight into the connection between mechanisms and related biochar properties during the anaerobic digestion of sewage sludge, which also provided an important clue to selecting, even harnessing desirable biochar material for a given biotechnological process.