Inoculum Concentration Research Articles

Integrated approach for removal of oil from contaminated seawater

ABSTRACT This study explores the possibility of oil removal from contaminated seawater using an integrated technology comprising of adsorption using human hair and phycoremediation using the indigenous algal strain Tetradesmus sp. NITD18. The sequential method demonstrated higher oil removal (81.5 ± 0.07%) compared to the simultaneous approach (77 ± 0.7%) after 12 days. Three experimental sets (A: 0.5 g, B: 0.6 g, C: 0.8 g) were designed based on varying amounts of human hair. Parametric studies revealed that optimal conditions were achieved with 0.8 g human hair and 150.9 g/L initial oil concentration during adsorption, yielding 62.5 ± 0.7% removal. During phycoremediation, 10% inoculum concentration showed maximum oil removal of 87 ± 0.14% and highest biomass production (0.127 ± 0.005 g/L). Set# C demonstrated a significant reduction in TDS (from 3925 ± 132 mg/L to 3338 ± 761 mg/L), salinity (from 3.9 ± 0.2 psu to 3.4 ± 0.3 psu), and conductivity (from 9079 ± 162 µS/cm to 4090 ± 141 µS/cm). Maximum concentrations of chlorophyll (48.2 ± 4.43 mg/L), protein (2.55 ± 0.002 mg/L), and carbohydrate (2.55 ± 0.002 mg/L) were obtained from spent algal biomass as obtained in a sequential approach. Hence, it can be stated that the study demonstrates that the sequential approach effectively removal oil from contaminated seawater under optimized conditions.

Exploring the intricate studies on low-density polyethylene (LDPE) biodegradation by Bacillus cereus AP-01, isolated from the gut of Styrofoam-fed Tenebrio molitor larvae.

This study aims to investigate the biodegradation potential of a gut bacterial strain, Bacillus cereus AP-01, isolated from Tenebrio molitor larvae fed Styrofoam, focusing on its efficacy in degrading low-density polyethylene (LDPE). The biodegradation process was evaluated through a series of assays, including clear zone assays, biodegradation assays, and planktonic cell growth assessments in mineral salt medium (MSM) over a 28-day incubation period. Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM) were employed to characterize the alterations in LDPE pellets, followed by molecular characterization. Over three months, sterile soil + LDPE pellets were treated with different concentrations of gut bacterial strain. The degradation capabilities were assessed by measuring pH, total microbial counts, carbon dioxide evolution, weight loss, and conducting phase contrast microscopy and mechanical strength tests. Results demonstrated that MSM containing LDPE as a carbon source with gut bacterial strain produced a clear zone and enhanced planktonic cell growth. FTIR analysis revealed the formation of new functional groups in the LDPE, while SEM images displayed surface erosion and cracking, providing visual evidence of biodegradation. Molecular characterization confirmed the strain as Bacillus cereus AP-01 (NCBI Accession Number: OR288218.1). A 10% inoculum concentration of Bacillus cereus AP-01 exhibited increased soil bacterial counts, carbon dioxide evolution, and pH levels, alongside a notable weight loss of 30.3% in LDPE pellets. Mechanical strength assessments indicated substantial reductions in tensile strength (7.81 ± 0.84 MPa), compression (4.92 ± 0.53 MPa), hardness (51.96 ± 5.62 shore D), flexibility (10.62 ± 1.15 MPa), and impact resistance (14.79 ± 0.94 J). These findings underscore the biodegradation potential of Bacillus cereus AP-01, presenting a promising strategy for addressing the global LDPE pollution crisis.

Recovery of Phenolic Compounds with Antioxidant Capacity Through Solid-State Fermentation of Pistachio Green Hull.

Pistachio green hull (PGH) represents the non-edible fraction obtained after the seed is harvested and is an important source of phenolic compounds. Solid-state fermentation (SSF) is a viable biotechnological and economical technique for extracting phenolic compounds. This study aimed to evaluate the SSF with Aspergillus niger GH1 to recover total phenolic compounds (TPC) with antioxidant capacity (AC) from PGH. For this, the time of higher TPC and AC (DPPH [2,2-diphenyl-1-picrylhydrazyl], ABTS [2,2-azinobis-(3-ethylbenzothiazoline-6-sulfonate)], FRAP [ferric reducing antioxidant power]) was selected. Then, moisture, inoculum concentration, and aeration rate were evaluated. A. niger GH1 was able to grow and colonize the PGH, with the higher value of TPC (23.83 mg/g of dry mass (gdm)) obtained after 24 h of culture, which significantly correlated with AC (Pearson's R = 0.69). Moisture and aeration rate were the main factors influencing TPC. The highest values for both TPC and AC were achieved in treatment 8 (60% moisture, 5 × 106 spores/mL, and 1 L/Kgwm min), resulting in a 129% and 1039% increase, respectively. Gallic acid 4-O-glucoside and geranine were identified in the PGH extracts using high-performance liquid chromatography coupled with mass spectrometry. The SSF provides eco-friendly alternatives for releasing bioactive compounds from PGH, adding value to this waste.

Degradation of Azo Dye by Dye-Degrading Bacteria

Synthetic aromatic compounds consisting of various functional groups are known as dyes. These colored compounds are often discharged in effluents, and they are very dangerous to aquatic life. The study was carried out to study potential azo dye-degrading bacteria. Bacteria were isolated from 9 soil and 7 effluent samples collected from different parts of Kathmandu Valley. Isolated bacteria were tested for dye tolerance and dye-tolerant bacteria were subjected to decolorization of three acid dyes: acid yellow 25, acid green 23 and acid orange 7. A change in optical density was observed to study the impact of inoculum concentration. All 19 isolated potential bacteria were identified by morphological and biochemical tests. Among these, 6 (60%) of Gram-positive and 4 (50%) of Gram-negative bacteria were dye tolerant. Three bacteria SO2-3W, SO3-4W and S16-4P were able to decolorize acid green 23. The impact of the increase in inoculum concentration was increased in decolorization percentage. SO2-3W, SO3-4W and S16-4P were identified as Bacillus spp. and Pseudomonas aeruginosa, respectively. The ability of Bacillus spp. and Pseudomonas spp. to tolerate and decolorize textile dyes at high concentrations encourages their use as a potential bioinoculant in the treatment of textile wastewater. Stam. J. Microbiol. 2024;14(1):1-4

Standardization of the Agar Plate Method for Bacteriophage Production.

The growing threat of antimicrobial resistance (AMR), exacerbated by the COVID-19 pandemic, highlights the urgent need for alternative treatments such as bacteriophage (phage) therapy. Phage therapy offers a targeted approach to combat bacterial infections, particularly those resistant to conventional antibiotics. This study aimed to standardize an agar plate method for high-mix, low-volume phage production, suitable for personalized phage therapy. Plaque assays were conducted with the double-layer agar method, and plaque sizes were precisely measured using image analysis tools. Regression models developed with Minitab software established correlations between plaque size and phage production, optimizing production while minimizing resistance development. The resulting Plaque Size Calculation (PSC) model accurately correlated plaque size with inoculum concentration and phage yield, establishing specific plaque-forming unit (PFU) thresholds for optimal production. Using phages targeting pathogens such as Escherichia, Salmonella, Staphylococcus, Pseudomonas, Chryseobacterium, Vibrio, Erwinia, and Aeromonas confirmed the model's accuracy across various conditions. The model's validation showed a strong inverse correlation between plaque size and minimum-lawn cell clearing PFUs (MCPs; R² = 98.91%) and identified an optimal inoculum density that maximizes yield while minimizing the evolution of resistant mutants. These results highlight that the PSC model offers a standardized and scalable method for efficient phage production, which is crucial for personalized therapy and AMR management. Furthermore, its adaptability across different conditions and phages positions it as a potential standard tool for rapid and precise phage screening and propagation in both clinical and industrial settings.

Optimization of the large-scale production for Erwinia amylovora bacteriophages

BackgroundFire blight, caused by Erwinia amylovora, poses a significant threat to global agriculture, with antibiotic-resistant strains necessitating alternative solutions such as phage therapy. Scaling phage therapy to an industrial level requires efficient mass-production methods, particularly in optimizing the seed culture process. In this study, we investigated large-scale E. amylovora phage production by optimizing media supplementation and fermenter conditions, focusing on minimizing seed phages and pathogenic strains to reduce risks and improve the seed culture process.ResultsWe optimized the phage inoculum concentrations and media supplements to achieve higher phage yields comparable to or exceeding conventional methods. Laboratory-scale validation and refinement for fermenter-scale production allowed us to reduce bacterial and phage inoculum levels to 10⁵ CFU/mL and 10³ PFU/mL, respectively. Using fructose and sucrose supplements, the yields were comparable to conventional methods that use 10⁸ CFU/mL host bacteria and 10⁷ PFU/mL phages. Further pH adjustments in the fermenter increased yields by 16–303% across all phages tested.ConclusionsWe demonstrated the successful optimization and scale-up of E. amylovora phage production, emphasizing the potential for industrial bioprocessing with the reduced use of host cells and phage seeds. Overall, by refining key production parameters, we established a robust and scalable method for enhancing phage production efficiency.

The Degradation Characteristics and Soil Remediation Capabilities of the Butachlor-Degrading Strain DC-1.

Butachlor is a widely utilized acetamide herbicide noted for its systemic selectivity against pre-emergence grass weeds. Butachlor has negative effects on organisms and the environment, so it is necessary to screen degradation strains. In this investigation, Bacillus cereus strain DC-1 was isolated from soil persistently exposed to butachlor. Through rigorous single-factor and response surface analyses, strain DC-1 exhibited a notable 87.06% degradation efficiency under optimized conditions where the temperature was 32.89 °C, pH was 7.29, and inoculum concentration was 5.18%. It was further hypothesized by LC-MS that the degradation pathway of butachlor by strain DC-1 might be as follows: butachlor undergoes initial deoxygenation catalyzed by dioxygenases to form 2-chloro-N-(2,6-diethylphenyl)-N-methylacetamide, followed by N-demethylation yielding 2-chloro-N-(2,6-diethylphenyl) acetamide, and culminating in conversion to 2,6-diethylphenol. In addition, bioremediation experiments of butachlor-contaminated soil were conducted. The results show that strain DC-1 could degradable 99.23% of butachlor (100 mg·kg-1) from the soil within 12 d, and soil sucrase, cellulase, and urease activities are promoted by the bacteria. And through high-throughput sequencing, it was concluded that the strain DC-1 was able to influence the relative abundance of certain bacteria in the soil, and make the microbial community in the soil develop in a more stable and beneficial direction. DC-1 thus represents a valuable resource in the realm of butachlor degradation due to its robust efficacy, favorable characteristics, and ecological restorative capabilities, underscoring its promising role in the bioremediation of butachlor-contaminated soils.

Optimization of Fermentation Process of Zanthoxylum bungeanum Seeds and Evaluation of Acute Toxicity of Protein Extract in Mice

The seeds of Zanthoxylum bungeanum seeds, a high-quality vegetable protein source, encounter application limitations due to their high molecular weight and anti-nutritional factors. This study focused on optimizing the fermentation process by investigating key parameters such as inoculation amount, inoculation ratio, material-to-liquid ratio, fermentation temperature, and fermentation time. Both single-factor experiments and response surface methodology were used to determine the optimal conditions. The effects of fermentation on particle size, surface morphology (scanning electron microscopy), water holding capacity, oil holding capacity, solubility, and emulsification properties of Zanthoxylum bungeanum seed protein were analyzed. In addition, acute toxicity was investigated at doses of 1.5 g/kg, 3 g/kg, 6 g/kg, and 12 g/kg. The results showed that the optimal fermentation conditions were an inoculum concentration of 10%, a ratio of Bacillus subtilis to Lactobacillus plantarum of 1:1, a material-to-liquid ratio of 0.8:1, a temperature of 35 °C, and a fermentation period of 4 days. Under these optimized conditions, the soluble protein content reached 153.1 mg/g. After fermentation, the functional properties of Zanthoxylum bungeanum seed protein improved significantly: the water holding capacity increased by 89%, the oil holding capacity by 68%, while the emulsifying activity and stability indices improved by 6% and 17%, respectively. The macromolecular proteins in the seeds of Zanthoxylum bungeanum were effectively broken down into smaller fragments during fermentation, resulting in a more folded and porous surface structure. In acute toxicity tests, all mice treated with fermented Zanthoxum seed protein survived for more than 7 days after injection, and there were no significant differences in body weight, organ index, and hematological tests between groups, but FZBSP of 1.5 g/kg~12 g/kg caused varying degrees of steatosis and inflammatory damage in the heart and liver. In conclusion, this study confirms that follow-up pilot studies using 1.5 g/kg FZBSP have the potential for further development and utilization.

Screening Method to Identify Watermelon Cultivars Resistant to Acidovorax citrulli, the Cause of Bacterial Fruit Blotch.

Acidovorax citrulli is a causative pathogen for bacterial fruit blotch (BFB) in Cucurbitaceae, including watermelon. The most effective method to control this plant disease is to cultivate resistant cultivars. Herein, this study aimed to establish an efficient screening method to determine the resistance of watermelon cultivars against A. citrulli. To this end, we explored the virulence of seven A. citrulli isolates belonging to clonal complex group I or II based on gltA gene analysis. Furthermore, we evaluated the BFB occurrence in the seedlings of two arbitrarily selected watermelon cultivars according to the growth stage of the watermelon seedlings, inoculum concentration, and incubation temperature after inoculation in a humidity chamber. Taken together, we established the following method to determine the resistance of watermelon cultivars against A. citrulli: watermelon seedlings at the fully expanded two-leaf stage can be spray-inoculated with an A. citrulli bacterial suspension at a concentration of 1.0 × 106 cfu/ml; after incubation for 48 h at 28℃ in a humidity chamber, the plants were cultivated in a growth chamber at 25℃ with 80% relative humidity under a 12-h light/dark cycle; and BFB occurrence on the plants can be investigated at 7 dpi by visual estimation of the diseased leaf area (%). Based on these experimental methods, we investigated the resistance degree of 43 commercial watermelon cultivars against A. citrulli KACC 17005. Therefore, our results can provide important information for the development of resistant cultivars against A. citrulli.

Optimization of inoculum cell concentration for enhanced lipid production in laboratory-scale cultivation of the marine microalga Chlorella sp. for biofuel applications

Microalgae are considered valuable bioresources due to their ability to produce high lipid content and grow under a variety of environmental conditions, making them strong candidates for sustainable biofuel production. However, the economic feasibility of microalgae-based biofuels depends on optimizing growth conditions in large-scale cultivation systems. This study investigates the effects of varying inoculum cell concentrations on the growth, lipid yield, and fatty acid composition of the locally isolated microalga Chlorella sp. SW5 in 2 L and 5 L cultivation systems. The results indicate that higher inoculum concentrations generally enhance biomass accumulation, with the 2 L system achieving the highest growth rate of 0.42 ± 0.01 day⁻1 at an inoculum concentration of 10⁶ cells/mL. Interestingly, while higher inoculum concentrations reduced lipid production in the 2 L system, the 5 L system showed the highest lipid yield (51.23% ± 4.71% dry weight) at the highest inoculum concentration (10⁷ cells/mL). Despite its moderate growth rate, the 5 L culture with a starting inoculum concentration of 10⁷ cells/mL was selected for fatty acid profiling due to its superior lipid yield and productivity. Gas chromatography-mass spectrometry (GC-MS) analysis revealed that the culture produced a total of 93.18% C14-C18 fatty acids, with a profile dominated by saturated (56.33%) and monounsaturated (16.85%) fatty acids, which are essential for biodiesel quality. These findings provide valuable insights into the potential for scaling up microalgal systems for commercial biofuel production, highlighting strategies to optimize productivity.

Innovation of tempeh from jack bean (Canavalia ensiformis) fermented with Mosaccha inoculum

Tempeh is a traditional Indonesian food made from soybeans fermented with Rhizopus oligosporus. The development of tempeh from jack beans fermented with a tempeh starter containing a combination of Rhizopus oligosporus and Saccharomyces cerevisiae (Mosaccha inoculum) represents a new innovation. This study aims to evaluate the influence of Mosaccha inoculum on the microbiological and sensory properties of jack bean tempeh. The experiment was designed using a Completely Randomized Block Design with a single factor at six levels, each repeated four times: 0.2% Mosaccha inoculum, 0.4%, 0.6%, 0.8%, 1%, and Raprima 0.5% as the control. The best jack bean tempeh was further analyzed for its nutritional content, HCN levels, and β-glucan content. The results showed that the addition of 0.6% Mosaccha inoculum produced the highest quality jack bean tempeh. This tempeh had a characteristic tempeh aroma with a slight yeast scent, a white color, evenly distributed mycelium growth, and a firm texture that did not easily crumble. Based on sensory evaluation, the taste and overall acceptability of this tempeh were well-liked. The best jack bean tempeh had a moisture content of 58.72%, total mold count of 7.58 log CFU/g, total yeast count of 8.99 log CFU/g, protein content of 15.83%, fat content of 10.92%, ash content of 1.14%, crude fiber content of 0.89%, HCN content of 2.47 ppm, and β-glucan content of 0.904%. This study demonstrates that jack bean tempeh produced with a 0.6% Mosaccha inoculum concentration offers a high-quality and nutritionally valuable alternative to traditional tempeh.

Degradation of Ciprofloxacin in Water Using Escherichia coli and Enterococcus faecium

The presence of antibiotics in the wastewater is a growing concern, as they tend to bioaccumulate and are increasing the resistance of bacteria. This study investigates the microbial degradation of ciprofloxacin (CIP) in water using Escherichia coli (E. coli) and Enterococcus faecium (E. faecium). This research aims to degrade the ciprofloxacin antibiotic, which is creating multiple problems in the environment and wastewater. Bacterial strains were isolated from wastewater and sludge samples, and their identities were confirmed through 16S rRNA sequencing. The degradation potential was assessed using a shake flask method under varying conditions, including different antibiotic concentrations, temperatures, pH levels, and inoculum densities. E. coli effectively degraded CIP, achieving 90% degradation at 50 mg/L in 18 days, in optimal conditions like a temperature of 37 °C, a pH of 6.5, and an inoculum concentration of 10−8 CFU/mL. However, at higher concentrations (150 mg/L), degradation decreased. Similarly, E. faecium showed a maximum degradation rate of 100% at 50 mg/L of CIP in 18 days, with optimal degradation occurring at 40 °C, a pH of 6.5, and an inoculum density of 10−8 CFU/mL. This study underscores the effectiveness of selected microbial strains in bioremediation processes, highlighting their potential application in mitigating antibiotic pollution in aquatic environments. This is the preliminary study to explore the potential of isolated bacteria to degrade CIP, and their degradation ability can be utilized to develop a CIP-contaminated wastewater treatment plant.

Bioremediation of Cr (VI) by novel microalgal strain

The present study aims at the isolation of Cr (VI) tolerant microalgae from wastewater collected from local bike garages. The wastewater had a continued spillage of engine oil, petrol, grease, and chain lube waste. The isolated microalgae were first sequenced by using 18S rRNA sequencing method. The nucleotide sequence obtained was analyzed via BLAST, the isolated microalga showed maximum similarity with Scenedesmus species. The sequence was submitted to NCBI, and the microalgae was identified as Scenedesmus species GTAF1 IU accession no. OM903800. The bioremediation potential of the isolated microalgae was evaluated for the removal of Cr (VI) in synthetic wastewater. The Cr (VI) removal efficiency was estimated at 0.2, 0.4, 0.6, and 0.8 g L−1 of inoculum concentration under autotrophic and heterotrophic modes. The highest removal efficiency of 98.9% and 99.9% was obtained at 0.8 g L−1 inoculum concentration under autotrophic and heterotrophic modes of operation respectively. On increasing the metal concentration from 5 to 10 ppm, a decrease in the biomass quality and quantity was observed. This increased metal stress resulted in an enhanced carbohydrate and lipid concentration. However, the protein concentration was found to be decreased. Cr (VI) removal efficiency was highest in heterotrophic conditions. This study provides a novel insight for removing Cr (VI) and concomitantly enhancing the lipid content of isolated strains under heterotrophic conditions. Owing to enhanced lipid content, the reported curation of wastewater may also be used in harnessing the potential of isolated microalga in biofuel production.

Postbiotic studies of mixed cultures of Schleiferilactobacillus harbinensis LH991 and Pichia kudriavzevii B-5P produced by in vitro rumen producing short-chain fatty acid.

Postbiotics are functional bioactive compounds or bioactive molecules with beneficial effects on health and functional activities in humans or livestock, produced by probiotic bacteria or yeast. Several postbiotics, including enzymes, short-chain fatty acids, amino acids, extracellular polysaccharides, microbial cell fragments, and teichoic acids, are currently being widely studied. This study aimed to explore the potential of secondary metabolites of Schleiferilactobacillus harbinensis LH 991 and Pichia kudriavzevii B-5P as lactic acid bacteria (LAB) and yeast isolated from Budu (fermented fish) which can act as postbiotics through in vitro rumen fermentation. The method used a completely randomized design 5 × 4, with five treatments and four replications. The substrate diet consisted of 60% forage and 40% concentrate. The culture mixture was 1.3 × 1011 CFU/mL with a 50%:50% ratio of S. harbinensis LH 991 and P. kudriavzevii B-5P. The inoculum concentrations used in this study were 0% (control), 1%, 2%, 3%, and 4%. Treatments are arranged based on differences in inoculum concentration as follows: T0: control (0%); T1: 1%; T2: 2%; T3: 3%; and T4: 4%. The T4 group showed a significant increase (p < 0.01) in short-chain fatty acids (SCFA), including acetate, propionate, butyrate, valerate, isobutyrate, and isovalerate acids, compared with the other treatments. Meanwhile, T4 shows that there is no significant (p > 0.01) effect on in vitro digestibility (in vitro dry matter digestibility, in vitro organic matter digestibility, and in vitro crude fiber digestibility). However, a highly significant (p < 0.01) effect was on volatile fatty acid total, NH3, and microbial crude protein synthesis. It is concluded that the treatment with a 4% inoculum concentration (T4) containing a mixture of S. harbinensis LH 991 and P. kudriavzevii B-5P as LAB and yeast isolated from Budu (fermented fish) in 50%:50% ratio increased SCFA and rumen fermentation significantly, whereas it did not affect in vitro digestibility.

Allelopathic interactions of Carthamus oxyacantha, Macrophomina phaseolina and maize: Implications for the use of Carthamus oxyacantha as a natural disease management strategy in maize.

Fungicides are used to control phytopathogens but all these fungicides have deleterious effects. Allelopathic interactions can be harnessed as a natural way to control the pathogens but there are no reports that show the allelopathic interactions of donor plant, recipient crop, as well as the target plant pathogen and the material used for inoculum production. So, in the present study, the suitability of Carthamus oxyacantha M. Bieb. was assessed against Macrophomina phaseolina, the cause of charcoal rot in maize. Among the various treatments in pot experiment, a negative control, 3 concentrations of inoculum (1.2×105, 2.4×105, and 3.6×105 colony forming units (CFU) mL-1, 3 concentrations (0.5, 1.0, and 1.5% w/w) of C. oxyacantha along with an autoclaved M. phaseolina (Mp) and C. oxyacantha alone were included to investigate their allelopathic effects on maize, not investigated earlier. Maximum suppression of the disease was observed by 1.5% (w/w) concentration of C. oxyacantha. Soil amendment with C. oxyacantha significantly suppressed the disease incidence (DI) and disease severity index (DSI) in charcoal rot of maize up to 40 and 55%, respectively over the strongest level of inoculum (Mp3). C. oxyacantha not only reduced area under disease incidence progress curve (AUDIPC) and area under disease severity progress curve (AUDSPC), but also improved the morphological, biochemical and physiological parameters of maize. The maximum increase of 48, 65, and 75% in values of shoot length (SL), shoot dry mass (SDM), and root dry mass (RDM), respectively was observed by application of the highest concentration of C. oxyacantha in the treatment Mp1+Co3, over infested control (Mp1). Photosynthetic pigments, such as chlorophyll a, chlorophyll b and carotenoids were increased to 58, 64, and 46%, respectively over Mp1, by the application of C. oxyacantha. Carbon assimilation rate (A), stomatal conductance (gs), rate of transpiration (E), and internal carbon dioxide concentration (Ci) were significantly increased to 58, 48, 48, and 20%, respectively over infested control (Mp3), by application of C. oxyacantha concentration 1.5 (w/w). Moreover, defense enzymes like superoxide dismutase (SOD), peroxidase (POD) and catalase (CAT) activities were boosted up to 27, 28, and 28% over Mp3, respectively. Positive allelopathy of C. oxyacantha towards maize and negative allelopathy towards M. phaseolina makes C. oxyacantha a suitable candidate for charcoal rot disease control in maize.

Optimization of Citrus Pulp Waste-Based Medium for Improved Bacterial Nanocellulose Production.

Bacterial nanocellulose (BC) has attracted significant attention across a wide array of applications due to its distinctive characteristics. Recently, there has been increasing interest in leveraging waste biomass to improve sustainability in BC biogenesis processes. This study focuses on optimizing the citrus pulp waste (CPW) medium to enhance BC production using Komagataeibacter sucrofermentans. The screening of initial medium pH, yeast extract, CPW sugar and inoculum concentrations was conducted using the Plackett-Burman design, with BC yield (mgDW/gCPW) as the model response. The significant parameters, i.e., CPW sugars and yeast extract concentrations, were optimized using response surface methodology, employing a five-level, two-factor central composite design. The optimized CPW-based growth medium resulted in a final yield of 66.7 ± 5.1 mgDW/gCPW, representing a 14-fold increase compared to non-optimized conditions (4.3 ± 0.4 mgBC/gCPW). Material characterization analysis indicated that the produced BC showed high thermal stability (30% mass retained at 600 °C) and a crystallinity index value of 71%. Additionally, to enhance process sustainability, spent baker's yeast hydrolysate (BYH) was assessed as a substitute for yeast extract, leading to a final BC titer of 9.3 ± 0.6 g/L.

Removal of Nitrogen, Phosphorus, Organic Matter, and Heavy Metals from Pig-Farming Wastewater Using a Microalgae-Bacteria Consortium

Wastewater generated by the pork industry urgently requires the implementation of low-cost, high-benefit, and efficient treatment systems. Accordingly, a microalgae-bacteria consortia-based treatment system is proposed for the removal of contaminants released, by the pork-producing industry, in swine wastewater. In this study, different inoculum concentrations of the microalgae-bacteria consortium were tested to document variation in the removal of nutrients from the wastewater. At varying concentrations, it was efficient and did not present a significant difference in the removal kinetics. The treatment with the greatest amount of inoculum removed close to 87% of total nitrogen, approximately 70% of orthophosphate, and 77% of chemical oxygen demand. Removals of 84% iron, 44% copper, and 48% manganese were also obtained. These results demonstrate that microalgae-bacteria consortia are an economically viable and environmentally desirable option for the efficient treatment of wastewater from the pork industry.

Microbial depolymerization of Kraft lignin for production of Vanillic acid by indigenous ligninolytic strains

Lignin is a potential renewable source for the production of many value-added bio-products through bacterial depolymerization. In this study, Kraft lignin (KL) was depolymerized by indigenous potential ligninolytic strains to obtain the optimum amount of Vanillic acid. Initially, fifteen bacterial strains were isolated from decaying wood mixed soil to assess their lignin degradation efficiency. Five potential lignin-degrading microbes (RW-B2, RW-B4, RW-B9, RW-B11 and RW-B15) were identified by nutrient enrichment technique. RW-B15 was observed as a dominant strain sharing a 99 % resemblance to Bacillus megaterium sp. Optimum temperature and bacterial inoculum concentration were noted as 35 °C and 1 %, respectively. Mixed microbial culture of five potential ligninolytic strains showed better KL degradation than pure culture due to different metabolic capacities, enzymatic mechanisms and synergetic impact among the association members. The KL degradation study was conducted with different KL concentrations (500–2000 mg/l) at optimum temperature using 1 % inoculums. The production of Vanillic acid increased from 60.1 to 199.9 mg/l with increasing concentration of KL from 500 to 2000 mg/l. The maximum production of Vanillic acid was obtained on 3rd day of degradation and it decreased thereafter which is probably due to an increase in microbial toxicity and enzymatic activity. However, the COD level continuously decreased for all KL concentrations with degradation time till the last day. The pH of the KL solution slightly decreased on 3rd day due to the acidic nature of Vanillic acid. GC-MS analysis confirmed the presence of Vanillic acid and showed the presence of other monomeric compounds formed after KL degradation.

Caproic acid production from short-chained carboxylic acids produced by arrested anaerobic digestion of green waste: Development and optimization of a mixed caproic acid producing culture

Caproic acid is an important compound for producing a variety of chemicals and a potential precursor for Sustainable Aviation Fuels (SAF). This study aimed at developing a stable mixed culture producing caproic acid using short-chain carboxylic acids (SCCAs) derived from arrested anaerobic digestion (AAD) of green waste and optimizing chain elongation (CE) conditions. The results showed that the mixed culture was dominated by Clostridium sensu stricto 12 (53.09 %), optimally producing caproic acid at 37 °C, pH 7.20, with a 15 % inoculum concentration. Under these conditions, 75.59 % of the consumed electrons contributed to caproic acid formation. Gradual ethanol feeding in bioreactor experiments resulted in caproic acid titer of 13.36 g/L, with carbon conversion efficiency (CCE) of 81.91 % and electron transfer efficiency (ETE) of 76.39 %, surpassing batch experiments without gradual ethanol addition. These findings demonstrate that the effectiveness of a mixed culture can be improved, resulting in increased caproic acid production.

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.