Inoculum Ratio Research Articles

Production of Bioactive Peptides from Tartary Buckwheat by Solid-State Fermentation with Lactiplantibacillus plantarum ATCC 14917.

Buckwheat is a valuable crop that contains various nutrients and functional components. Tartary buckwheat peptide is a protease-hydrolyzed protein with a wide range of physiological functions. Tartary buckwheat peptide produced through microbial fermentation can decrease the enzymatic digestion of buckwheat protein, which contributes to the bitter taste, and improve both the flavor and texture of buckwheat peptide products. In this study, microbial fermentation using probiotics was employed to prepare Tartary buckwheat peptides, and the preparation process was optimized. Based on single-factor experiments, the polypeptide content in the fermentation solution initially increased and then decreased with varying water content, inoculum concentration, glucose addition, fermentation temperature, fermentation time, and potassium dihydrogen phosphate addition. According to the response surface methodology, the maximum peptide content was achieved under fermentation conditions of 60.0% moisture content, 12.87% inoculum ratio, 2.0% glucose, and a fermentation temperature of 30.0 °C, with an actual value of (22.18 ± 1.02) mg/mL. The results show that fermentation with Lactiplantibacillus plantarum produces higher peptide levels and is safer than other microbial fermentation methods.

Technical feasibility and modeling of enzymatic pre-treatments of organic fraction of municipal solid waste to improve anaerobic digestion

The study explored the combined effects of enzymatic pre-treatment and anaerobic digestion (AD) on the organic fraction of municipal solid wastes (OFMSW) through experimental and multicriteria decision-making approaches. Five enzymes (UPP2, MPCS, USC4, USE2, and A. niger) and their dosages were studied. AD parameters included two inoculum origins (waste active sludge - WAS - and cow-agricultural sludge - CAS), the substrate: inoculum (SI) ratio, and inoculum incubation time (INOC). Desirability functions were used to optimize the multiple experimental responses simultaneously by converting each of them into values from 0 (unacceptable) to 1 (completely acceptable) and then combining these into a global desirability (D). D highlighted that higher enzyme dosages, INOC, and SI, improved AD performances, with optimal DOSE (at the highest level adopted for each enzyme) and INOC (5–10 d). AD tests with the five enzymes increased CH4 production by 10–13%v/v compared to untreated OFMSW. For UPP2 and MPCS, increasing DOSE boosted the biogas production, while increasing INOC enhanced the CH4 content. MPCS reached the highest efficiency (478. 43 NL CH4/kg VS with CAS, SI = 2:1, INOC = 10 d), followed by UPP2. Furthermore, higher INOC reduced A. niger doses, increasing CH4 production by 9%v/v compared to literature, with 5–10 d INOC (452.86 NL s/kg VS with WAS, SI = 2:1).

Isolation and Molecular Characterisation of Chlorogonium sp. from Industrial Wastewater

Microalgae are photosynthetic, unicellular microorganisms also known as phytoplankton. They are small plant-like entities. In this research, the sample were collected from cement factory in a sterilised 20L container wrapped with foil paper and were transported down to Federal University, Wukari where it was kept in refrigerator at biochemistry laboratory. Blue-Green media (BG-11) was prepared. Wastewater containing Microalgae obtained from cement wastewater pond were cultivated in BG-11 medium to determine the growth of the organism. BG-11 medium contained macronutrients, trace metals and some vitamins which aid the growth of the organism. The wastewater sample containing with suspected microalgae was inoculated (inoculum ratio = 25%) and incubated under atmospheric CO2 at room temperature (30±2°C) in our laboratory for two to three weeks during the incubation period. In order to purify the isolates, the upper growth layer was first decanted into a freshly produced medium and then plated on BG-11 media that had been solidified with 1% agar-agar. For several of the cultures, growth on the agar plates continued for around three weeks. Following repeated sub-culturing, the emerging greenish colonies were re-emerged into a sterile BG-11 agar medium. In isolation of organism from the industrial cement waste water, the isolate was identified by morphological and molecular identification by extracting the DNA, run the electrophoretic analysis and PCR using primers for 18S rRNA eukaryotic microalgal and then run the sequence analysis. The results of this study obtained, indicated that, the electrophoretic result show the band has 1800-2000base pair and the organism isolated from the industrial cement waste water were chlorogonium sp. with a percent similarity of 78.65% and accession number of OR886595 based on data Gene Bank blast results.

Co-cultivation of microalgae and bacteria for optimal bioenergy feedstock production in wastewater by using response surface methodology

This work uses response surface methodology (RSM) to study the co-cultivation of symbiotic indigenous wastewater microalgae and bacteria under different conditions (inoculum ratio of bacteria to microalgae, CO2, light intensity, and harvest time) for optimal bioenergy feedstock production. The findings of this study demonstrate that the symbiotic microalgae-bacteria culture not only increases total microalgal biomass and lipid productivity, but also enlarges microalgal cell size and stimulates lipid accumulation. Meanwhile, inoculum ratio of bacteria to microalgae, light intensity, CO2, and harvest time significantly affect biomass and lipid productivity. CO2 concentration and harvest time have significant interactive effect on lipid productivity. The response of microalgal biomass and lipid productivity varies significantly from 2.1 × 105 to 1.9 × 107 cells/mL and 2.8 × 102 to 3.7 × 1012 Total Fluorescent Units/mL respectively. Conditions for optimum biomass and oil accumulation are 100% of inoculation ratio (bacteria/microalgae), 3.6% of CO2 (v/v), 205.8 µmol/m2/s of light intensity, and 10.6 days of harvest time. This work provides a systematic methodology with RSM to explore the benefits of symbiotic microalgae-bacteria culture, and to optimize various cultivation parameters within complex wastewater environments for practical applications of integrated wastewater-microalgae systems for cost-efficient bioenergy production.

Strategies for improvement of bioactive compounds production using microalgal consortia: An emerging concept for current and future perspective

In recent times, microalgae have been recognized as one of the most potential sources of biomolecules with therapeutic potential. Microalgae are rich sources of polyunsaturated fatty acids, proteins, carbohydrates, carotenoids, and vitamins. These compounds have significant anticancer, antioxidant, anti-aging, antidiabetic, hepatoprotective, and anti-inflammatory potentials. Until now, monoculture of microalgae has been the most preferred way to produce these compounds. However, this method faces the challenge of low biomass and biomolecule production and a high risk of contamination. Controlled symbiotic co-culture of microalgae with suitable microorganisms can overcome these challenges. Therefore, it is crucial to explore the compatibility of microalgae with other microorganisms to develop novel consortia to enhance biomass and biomolecule production. The article comprehensively reviews the strategies for the improvement of bioactive compound production using microalgal consortia (SIBCP-MC) viz. microalgae, fungi, bacteria, and cyanobacteria. It also discusses the mechanisms of their interaction, economic viability, and a comparison of expected revenue generation from different types of microalgal consortia. The review mainly focuses on the therapeutic potentials of microalgae biomolecules and the optimization of different factors, such as the selection of consortium partners, inoculum ratio, cultivation types and modes, temperature, pH, light intensity, and photoperiod, that affect the biomass and biomolecule production of microalgal consortia which in future helps in enhancement in biomass and biomolecules production from microalgae and curing chronic diseases. The review discusses various types of microalgal consortia, aiding in selecting the most suitable consortia for future use. The review compares their biomass and biomolecule production with monoculture, outlining microalgal consortia's advantages, challenges, and prospects. Additionally, it discusses advanced artificial intelligence techniques that could assist in the future in the selection of compatible organisms and predict expected revenue generation.

Enhanced inhibitory efficiency against toxic bloom forming Raphidiopsis raciborskii by Streptomyces sp. HY through triple algicidal modes: Direct and indirect attacks combined with bioflocculation

Raphidiopsis raciborskii (R. raciborskii) forms harmful cyanobacterial blooms globally, and poses a great threat to the safety of drinking water and public health. There is a great need to develop eco-friendly biological alternative measures to mitigate mass blooms of R. raciborskii. However, previous rare studies on algicidal microorganisms against R. raciborskii restricted this aim. Recently, an algicidal bacterium Streptomyces sp. HY (designated HY) was identified with flavones producing ability, and could remove up to 98.73 % of R. raciborskii biomass within 48 h by directly attacking the cyanobacterium and release of algicidal substances (i.e., flavonoids) with a inoculum ratio of 5 %. Algicidal rate of HY was enhanced by 88.05 %, 89.33 % under dark and light, and full-light conditions respectively, when compared with the dark condition. Its algicidal substances were stable in a broad range of temperature (−80–55 °C) and pH (3−11) conditions, and all treated groups exhibited ≈ 100 % algicidal rate at day 3. HY treatment disrupted the photosynthesis system and triggered serious oxidative stress resulting in severe morphological injury. Thereby, HY treatment significantly affected expression levels of several essential genes (i.e., psbA, psaB, rbcL, ftsZ, recA, grpE), and simultaneously inhibited the biosynthesis and release of cylindrospermopsin. Yet, HY treatment didn’t show any toxicity to zebrafish test embryos. Such results indicate that HY is a promising algicidal candidate strain to control global R. raciborskii blooms, and holds great promises for an effective biological measure to sustain water safety.

Optimization of polysaccharide conditions and analysis of antioxidant capacity in the co-culture of Sanghuangporus vaninii and Pleurotus sapidus

Fungal polysaccharides are commonly utilized in the food industry and biomedical fields as a natural and safe immune modulator. Co-culturing is a valuable method for enhancing the production of secondary metabolites. This study used intracellular polysaccharide (IPS) content as a screening index, co-culturing seven different fungi with Sanghuangporus vaninii. The seed pre-culture liquid culture time was selected through screening, and conditions were assessed using single factor experimentation, a Plackett-Burman (PB) design, and response surface methodology (RSM) optimization. RSM optimization was conducted, leading to the measurement of antioxidant capacity. Results indicated that the co-culture of S. vaninii and Pleurotus sapidus exhibited the most effective outcome. Specifically, pre-culturing S. vaninii and P. sapidus seed cultures for 2 days and 0 days, respectively, followed by co-culturing, significantly increased IPS content compared to single-strain culturing. Further optimization of co-culture conditions revealed that yeast extract concentration, liquid volume, and S. vaninii inoculum ratio notably influenced IPS content in the order of yeast extract concentration > liquid volume > S. vaninii inoculum ratio. Under the optimal conditions, IPS content reached 69.9626 mg/g, a 17.04% increase from pre-optimization co-culture conditions. Antioxidant capacity testing demonstrated that co-cultured IPS exhibited greater scavenging abilities for DPPH and ABTS free radicals compared to single strain cultures. These findings highlight the potential of co-culturing S. vaninii and P. sapidus to enhance IPS content and improve antioxidant capacity, presenting an effective strategy for increasing fungal polysaccharide production.

Effect of Hanseniaspora vineae and Saccharomyces cerevisiae co-fermentations on aroma compound production in beer

In recent years, the boom of the craft beer industry refocused the biotech interest from ethanol production to diversification of beer aroma profiles. This study analyses the fermentative phenotype of a collection of non-conventional yeasts and examines their role in creating new flavours, particularly through co-fermentation with industrial Saccharomyces cerevisiae. High-throughput solid and liquid media fitness screening compared the ability of eight Saccharomyces and four non-Saccharomyces yeast strains to grow in wort. We determined the volatile profile of these yeast strains and found that Hanseniaspora vineae displayed a particularly high production of the desirable aroma compounds ethyl acetate and 2-phenethyl acetate. Given that H. vineae on its own can't ferment maltose and maltotriose, we carried out mixed wort co-fermentations with a S. cerevisiae brewing strain at different ratios. The two yeast strains were able to co-exist throughout the experiment, regardless of their initial inoculum, and the increase in the production of the esters observed in the H. vineae monoculture was maintained, alongside with a high ethanol production. Moreover, different inoculum ratios yielded different aroma profiles: the 50/50 S. cerevisiae/H. vineae ratio produced a more balanced profile, while the 10/90 ratio generated stronger floral aromas. Our findings show the potential of using different yeasts and different inoculum combinations to tailor the final aroma, thus offering new possibilities for a broader range of beer flavours and styles.

Upgrading soybean dreg to caproate via intermediate of lactate and mediator of biochar

To address the environmental hazards posed by high-yield soybean dreg (SD), a high-value strategy is firstly proposed by synthesizing caproate through chain elongation (CE). Optimized conditions for lactate-rich broth as intermediate, utilizing 50 % inoculum ratio, 40 g/L substrate concentration, and pH 5, resulting in 2.05 g/L caproate from direct fermentation. Leveraging lactate-rich broth supplemented with ethanol, caproate was optimized to 2.76 g/L under a refined electron donor to acceptor of 2:1. Furthermore, incorporating 20 g/L biochar elevated caproate production to 3.05 g/L and significantly shortened the lag phase. Mechanistic insights revealed that biochar’s surface-existed quinone and hydroquinone groups exhibit potent redox characteristics, thereby facilitating electron transfer. Moreover, biochar up-regulated the abundance of key genes involved in CE process (especially fatty acids biosynthesis pathway), also enriching Lysinibacillus and Pseudomonas as an unrecognized cooperation to CE. This study paves a way for sustainable development of SD by upgrading to caproate.

Anaerobic digestion of herbal waste: a waste to energy option.

Herbal waste produced during the manufacturing of herbal products is a potential feedstock for anaerobic digestion due to high amount of organic matter that can be transformed into biogas as an energy resource. Therefore, the present study was undertaken to convert herbal waste produced during the manufacturing of common of Ayurveda products into biogas through anaerobic digestion process using batch test study under controlled mesophilic temperature conditions of 35°C with food to inoculum ratio of 0.75. The maximum biomethane potential (BMP) of 0.90 (gCH4COD/g CODfed) and sludge activity of 0.70 (gCH4-CD/gVSS) was exhibited by WS herbal waste owing to its high chemical oxygen demand (COD) of 4g/g and better solubilization potential of the organic matter showing change in volatile suspended solids (ΔVSS) of 79%. On the other hand, the waste derived from the TA herb, exhibited the least biogas yield of 0.55 (gCH4COD/g CODfed) and sludge activity of 0.40 (gCH4-CD/gVSS), albeit with higher organic matter present. This was due to the possible hindrance of waste solubilization by the presence of lignin. The waste derived from VVL and PE showed intermediate BMP and sludge activity. The methane generation rate constant (k), a key indicator of the biodegradation potential, was also evaluated. The k values showed similar trend as of BMP values ranging from 0.081 to 0.15 d-1 thus indicating the influence of presence of lignin and the change in ΔVSS. The present study proves anaerobic digestion to be an alternative treatment method to be a milestone for management of herbal wastes and can be successfully implemented on real-scale systems.

PROPORTIONAL EVALUATION OF WATER HYACINTH AS A RAW MATERIAL FOR BIOGAS, BIOMANURE AND SOIL CONDITIONER GENERATION VIA ANAEROBIC PROCESSES AT LAB AND PILOT SCALE

Water hyacinth is capable of inexplicably conceal an entire water body within two weeks by forming thick mats due to its rapid proliferation intimidating the existence of aquatic organisms. Therefore, this study is aimed to investigate the conversion of WH to biogas, biomanure and soil conditioner (SC) through anaerobic digestion (AD) and composting process. While composting was studied at the lab and pilot scale using leaves and roots, the AD of WH at various food to inoculum (F/I) ratios of 1, 2, and 5 was carried out with leaves, roots, and a mixture of leaves and roots. The study found that leaves can efficiently produce biogas at a 2:1 F/I ratio with 350 mL/g VS reduced methane and 63% CH4. The qualitative evaluation of biomanure and SC from AD and composting processes revealed that the SC produced from leaves is suitable for agriculture farming (Fenugreek and Coriandrum Sativum) while that of roots for horticulture (Hibiscus and Papaya). About 1200 tons of WH was converted to 120 tons of soil conditioner to control the WH growth in Kapra Lake in Hyderabad city.

Treponema pallidum subsp. pallidum strains DAL-1 and Philadelphia 1 differ in generation times in vitro as well as during experimental rabbit infection.

In this work, we determined that Treponema pallidum subsp. pallidum (TPA) DAL-1 (belonging to Nichols-like group of TPA strains) grew 1.53 (± 0.08) times faster compared to TPA Philadelphia 1 (SS14-like group) during in vitro cultivations. In longitudinal individual propagation in rabbit testes (n = 12, each TPA strain), infection with DAL-1 manifested clinical symptoms (induration, swelling, and erythema of testes) sooner than Philadelphia 1 infection, which resulted in a significantly shorter period of the experimental passages for DAL-1 (median = 15.0 and 23.5 days, respectively; p < 0.01). To minimize the confounding conditions during rabbit experiments, the growth characteristics of DAL-1 and Philadelphia 1 strains were determined during TPA co-infection of rabbit testes (n = 20, including controls). During two weeks of intratesticular co-infection, DAL-1 overgrew Philadelphia 1 in all twelve testes, regardless of inoculation ratio and dose (median of relative excess DAL-1 multiplication = 84.85×). Moreover, higher DAL-1 to Philadelphia 1 inoculum ratios appeared to increase differences in growth rates, suggesting direct competition between strains for available nutrients during co-infection. These experiments indicate important physiological differences between the two TPA strains and suggest growth differences between Nichols-like and SS14-like strains that are potentially linked to their virulence and pathogenicity.

Improvement of cell growth in green algae Chlamydomonas reinhardtii through co-cultivation with yeast Saccharomyces cerevisiae.

CO2 fixation methods using green algae have attracted considerable attention because they can be applied for the fixation of dilute CO2 in the atmosphere. However, green algae generally exhibit low CO2 fixation efficiency under atmospheric conditions. Therefore, it is a challenge to improve the CO2 fixation efficiency of green algae under atmospheric conditions. Co-cultivation of certain microalgae with heterotrophic microorganisms can increase the growth potential of microalgae under atmospheric conditions. The objective of this study was to determine the culture conditions under which the growth potential of green algae Chlamydomonas reinhardtii is enhanced by co-culturing with the yeast Saccharomyces cerevisiae, and to identify the cause of the enhanced growth potential. When C. reinhardtii and S. cerevisiae were co-cultured with an initial green algae to yeast inoculum ratio of 1:3, the cell concentration of C. reinhardtii reached 133 × 105cells/mL on day 18 of culture, which was 1.5 times higher than that of the monoculture. Transcriptome analysis revealed that the expression levels of 363 green algae and 815 yeast genes were altered through co-cultivation. These included genes responsible for ammonium transport and CO2 enrichment mechanism in green algae and the genes responsible for glycolysis and stress responses in yeast. We successfully increased C. reinhardtiigrowth potential by co-culturing it with S. cerevisiae. The main reasons for this are likely to be an increase in inorganic nitrogen available to green algae via yeast metabolism and an increase in energy available for green algae growth instead of CO2 enrichment.

Bioethanol production from sugarcane molasses by co-fermentation of Saccharomyces cerevisiae isolate TA2 and Wickerhamomyces anomalus isolate HCJ2F-19

PurposeCo-culturing is a widely used method to improve bioethanol production from biomass enriched in fermentable sugars. This study aims to produce bioethanol from sugarcane molasses by simultaneous co-fermentation of S. cerevisiae isolate TA2 and W. anomalus isolate HCJ2F-19.MethodsResponse surface methodology (RSM) based on the central composite design (CCD) was employed to optimize fermentation conditions, including mixing rate (110–150 rpm), temperature (25–35 °C), molasses concentration (25–35 obrix), and incubation time (36–72 h). The ethanol concentration was analyzed using HPLC equipped with a UV detector.ResultsThe monocultureS. cerevisiae isolate TA2 produced 17.2 g.L−1 of ethanol, 0.33 g.g−1 of ethanol yield, and 0.36 g.L−1.h−1 of productivity compared to W. anomalus isolate HCJ2F that produced 14.5 g.L−1, 0.30 g.g−1 and 0.28 g.L−1.h−1 ethanol, ethanol yield, and productivity under laboratory conditions, respectively. In comparison to single cultures of S. cerevisiae TA2 and W. anomalus HCJ2F, the co-fermentation using both isolates showed an increased ethanol yield of 29% and 53% compared to the single species fermentations, respectively. The results showed that the growth of W. anomalus HCJ2F-19 and S. cerevisiae TA2 was not influenced by each other during the co-fermentation process. The one variable at a time optimization (OVAT) analysis resulted in an ethanol concentration of 26.5 g.L−1 with a specific yield and productivity of 0.46 g.g−1, 0.55 g.L−1.h−1, respectively, at pH 5.5, 25 obrix, 48 h, 150 rpm, 30 °C, 60:40 inoculum ratio, and 10% overall inoculum size. The maximum ethanol concentration of 35.5 g.L−1 was obtained by co-fermentation using the RSM-CCD tool at 30 obrix, 30 °C, 54 h, and 130 rpm.ConclusionThe results suggested that the co-fermentation of S. cerevisiae isolate TA2 and W. anomalus isolate HCJ2F improves bioethanol production from sugar cane molasses under optimum fermentation conditions.

Optimization of Fermentation and Sensory Quality of Mango Yogurt Using Various Sucrose Concentration Fermented by Lacticaseibaciluus paracasei Strain Shirota

This research explores the optimization of mango yogurt production, leveraging mango as the primary fermentation ingredient and Lacticaseibacillus paracasei strain Shirota (LcS) as the probiotic inoculum. Traditional yogurt, typically derived from animal milk, faces competition from plant-based alternatives. The research objective is to investigate the impact of inoculum ratios and sucrose concentrations on LcS density and sensory attributes, with a focus on the Substrate to Inoculum Ratio (S/I) as a critical parameter influencing microbial metabolism and population dynamics. Various inoculum ratios (1:1, 1:2, 1:4, 1:8 v/v) and sucrose concentrations (0%, 2.5%, 5%, 7.5%) were applied in mango yogurt production. Results from ANOVA analysis indicated significant differences in LcS density among inoculum ratios (F3,16 = 37.01, P = 0.000) and sucrose concentrations (F3,16 = 19.07, P = 0.000). The 1:2 inoculum ratio and 7.5% sucrose concentration emerged as optimal, as evidenced by stable pH conditions and lactic acid profiles within recommended standards. Sensory analysis, employing a 5-point hedonic scale for color, odor, taste, and texture evaluation, revealed moderate acceptance. In conclusion, this study introduces an innovative approach to mango yogurt production, highlighting the potential of specific inoculum ratios and sucrose concentrations for optimal results. The findings contribute to the broader landscape of plant-based yogurt alternatives, underscoring the need for ongoing refinement to meet commercial standards and ensure consumer satisfaction.

Optimization of Solid-State Fermentation Conditions With Mixed Strains Using Box-Behnken Design for the Production of brewers’ Spent Grain Protein

As the most abundant by-product of the brewing industry, the valorization of proteins from brewers’ spent grains (BSG) is critical to reducing processing waste and meeting the growing demand for plant-derived protein globally. However, the applicability of brewers’ spent grain proteins in food manufacturing has been constrained by the high extraction cost and undesirable functionalities. In this research, BSG was used as the substrate to ferment with the mixed strains Bacillus subtilis, Saccharomyces cerevisiae, and Kluyveromyces marxianus and then subjected to protein extraction. The solid-state fermentation (SSF) conditions were optimized using single-factor tests together with Box-Behnken Design to 50% initial moisture content, 10% strain inoculum ratio, fermented at pH 5.8 under 32 °C for 6 days, with the highest soluble protein concentration of 0.678 ± 0.0047 µg/µL (equivalent to bovine serum albumin). Furthermore, proteins were extracted from unmalted raw barley grains and BSG control (with a yield of 0.338 ± 0.016 µg/µL and 0.352 ± 0.015 µg/µL, respectively) and then evaluated for their physiochemical characterizations as a comparison of solid-state fermented proteins. The physicochemical attributes of all the intact proteins were similar, except that the fermented samples showed a smaller molecular mass on the SDS-PAGE gel. In conclusion, these results indicated that SSF is a feasible strategy for the bioconversion of BSG into valuable food ingredients as it enhances protein extraction efficiency while reducing the production cost, thereby being beneficial to alleviate the associated environmental pollution and to broaden its possibilities for further integration into the circular economy.

Enhanced hydrolysis and acidification of corn straw via liquid fraction of digestate: Environmental adaptability and microbial mechanisms

Anaerobic digestion (AD) of abandoned straws is an eco-friendly approach to realize its recycling. However, the low hydrolysis rate of lignocellulose poses a hindrance to achieving efficient AD. In this study, the enhanced hydrolysis and acidification of corn straw (CS) utilizing the liquid fraction of digestate (LFD) was investigated across varying solid-to-liquid inoculum ratio (SIR), pH levels, and temperature conditions. The succession patterns of the microbial community, driven by different parameters, were simultaneously identified. The findings revealed that the optimal yield of volatile fatty acids (VFAs) was observed under conditions with an SIR of 4, pH of 10, and a temperature of 45℃, predominantly dominated by acetic acid. And both pH and temperature were not conducive to VFAs accumulation in extreme environments. Comparatively, changes in pH had a greater impact on the acid production of the LFD-enhanced system and was also the primary environmental factor leading to differentiation in microbial community structure. Although Firmicutes was an absolutely dominant bacterium at the phylum level, the abundances of Caproiciproducens and Clostridum_sensu_stricto_1 at the genus level, mainly transforming complex organic substances into simpler metabolic byproducts, were greatly sensitive to the variations in SIR, pH, and temperature. This study could have practical implications for guiding improvements in large-scale AD systems with lignocellulosic straws.

Unlocking synergies: Harnessing the potential of biological methane sequestration through metabolic coupling between Methylomicrobium alcaliphilum 20Z and Chlorella sp. HS2

A halotolerant consortium between microalgae and methanotrophic bacteria could effectively remediate in situ CH4 and CO2, particularly using saline wastewater sources. Herein, Methylomicrobium alcaliphilum 20Z was demonstrated to form a mutualistic association with Chlorella sp. HS2 at a salinity level above 3.0%. Co-culture significantly enhanced the growth of both microbes, independent of initial inoculum ratios. Additionally, increased methane provision in enclosed serum bottles led to saturated methane removal. Subsequent analyses suggested nearly an order of magnitude increase in the amount of carbon sequestered in biomass in methane-fed co-cultures, conditions that also maintained a suitable cultural pH suitable for methanotrophic growth. Collectively, these results suggest a robust metabolic coupling between the two microbes and the influence of the factors other than gaseous exchange on the assembled consortium. Therefore, multi-faceted investigations are needed to harness the significant methane removal potential of the identified halotolerant consortium under conditions relevant to real-world operation scenarios.

Formation of a constructed microbial community in a nutrient-rich environment indicates bacterial interspecific competition.

Bacteria naturally co-exist in multispecies consortia, and the ability to engineer such systems can be useful in biotechnology. Despite this, few studies have been performed to understand how bacteria form a stable community and interact with each other under nutrient-rich conditions. In this study, we investigated the effects of initial inoculum ratios on bacterial community structure using a complex medium and found that the initial inoculum ratio has no significant impact on resultant community structure or on interaction patterns between community members. The microbial population profiles were simulated using computational tools in order to understand intermicrobial relationships and to identify potential metabolic exchanges that occur during stabilization of the bacterial community. Studying microbial community assembly processes is essential for understanding fundamental ecological principles in microbial ecosystems and can be critical in predicting microbial community structure and function.

Acetone-Butanol-Ethanol (ABE) fermentation with clostridial co-cultures for enhanced biobutanol production

This study has addressed the issue of enhanced biobutanol production through Consolidated Bioprocessing, with the use of clostridial co-cultures combining C. acetobutylicum (Cac) and C. pasteurianum (Cpa). To begin with, the total Acetone-Butanol-Ethanol (ABE) solvent production and butanol selectivity of individual clostridial cultures grown on different carbon sources present in lignocellulosic hydrolysates. Thereafter, statistical optimization of ABE fermentation with co-culture system was carried out using Box-Behnken design. The optimization variables were Cac to Cpa inoculum ratio (X1 in mL mL−1), sodium concentration in the medium (X2 g L−1), and xylose/glucose ratio (X3 g g−1 L L−1), whereas response variables were butanol titre (Y1 in g L−1), biomass growth (Y2 OD600), total ABE titre (Y3 in g L−1). Maximum values of the response variables with the corresponding set of optimization parameters were as follows: Y1, max = 12.1 ± 0.45 (for X1 = 0.30, X2 = 5.90, X3 = 0), Y2, max = 4.15 ± 0.03 (for X1 = 0.3, X2 = 2.42, X3 = 0.14), Y3, max = 23.1 ± 0.55 (for X1 = 0.46, X2 = 6.36, X3 = 0). The study demonstrated a substantial ≈ 22% and 61% increment in butanol titre in co-culture system compared to individual fermentations with Cac and Cpa grown on pure glucose, respectively.