The purpose of the NaOH pretreatment of rice straw with a recycling strategy was to enhance the economic efficiency of producing biomethane. Anaerobic digestion is used for converting rice straw into biogas. In this work, 5% NaOH and rice straw mixed samples were autoclaved at 121 °C for 20 min for lignin removal. The NaOH black liquor was separated using filtration for the subsequent treatment cycle. The NaOH liquor was utilized in one more subsequent recycling procedure to test its ability to remove lignin from the rice straw. The 5% NaOH treatment results in a reduction in rice straw (RC) lignin of 73.6%. The lignin content of the recycled NaOH-filtrated rice straw samples (RCF1) was reduced by 55.5%. The 5% NaOH-treated rice straw sample yields a total cumulative biogas of 1452.4 mL/gVS, whereas the recycled NaOH-filtered (RCF1) samples generate 1125.2 mL/gVS after 30 days of incubation. However, after 30 days of incubation, the untreated rice straw (RCC) bottle produced a total of 285.5 mL/gVS of biogas. The total increase in methane output after NaOH treatment is 6–8 times greater, and the biogas yield improves by 80–124%. We show here that the recycled NaOH black solution has still the effectiveness to be used for successive pretreatment cycles to remove lignin and generate methane. In the meantime, the NaOH black solution contains useful materials (lignin, sugars, potassium, and nitrogen) that could be purified for commercial purposes, and more importantly recycling the NaOH solution decrease the chances of environmental pollution. Thus, recycling NaOH decreased chemical consumption, which would provide net benefits instead of using fresh NaOH solution, had a lower water consumption, and provided the prospect of producing an optimum yield of methane in anaerobic digestion. This method will decrease the chemical treatment costs for biomass pretreatment prior to anaerobic digestion. Recycling of NaOH solution and the integration of pretreatment reactors could be a novel bioprocessing addition to the current technology.

Generally wastewater such agricultural runoff is considered a nuisance; however, it could be harnessed as a potential source of nutrients like nitrates and phosphates in integrated biorefinery context. In the current study, microalgae Chlorella sp. S5 was used for bioremediation of agricultural runoff and the leftover algal biomass was used as a potential source for production of biofuels in an integrated biorefinery context. The microalgae Chlorella sp. S5 was cultivated on Blue Green (BG 11) medium and a comprehensive optimization of different parameters including phosphates, nitrates, and pH was carried out to acquire maximum algal biomass enriched with high lipids content. Dry biomass was quantified using the solvent extraction technique, while the identification of nitrates and phosphates in agricultural runoff was carried out using commercial kits. The algal extracted lipids (oils) were employed in enzymatic trans-esterification for biodiesel production using whole-cell biomass of Bacillus subtilis Q4 MZ841642. The resultant fatty acid methyl esters (FAMEs) were analyzed using Fourier transform infrared (FTIR) spectroscopy and gas chromatography coupled with mass spectrometry (GC–MS). Subsequently, both the intact algal biomass and its lipid-depleted algal biomass were used for biogas production within a batch anaerobic digestion setup. Interestingly, Chlorella sp. S5 demonstrated a substantial reduction of 95% in nitrate and 91% in phosphate from agricultural runoff. The biodiesel derived from algal biomass exhibited a noteworthy total FAME content of 98.2%, meeting the quality standards set by American Society for Testing and Materials (ASTM) and European union (EU) standards. Furthermore, the biomethane yields obtained from whole biomass and lipid-depleted biomass were 330.34 NmL/g VS_added and 364.34 NmL/g VS_added, respectively. In conclusion, the findings underscore the potent utility of Chlorella sp. S5 as a multi-faceted resource, proficiently employed in a sequential cascade for treating agricultural runoff, producing biodiesel, and generating biogas within the integrated biorefinery concept. Graphical Abstract

This study used conservative one variable-at-a-time study and statistical surface response methods to increase the yields of an extracellular thermostable protease secreted by a newly identified thermophilic Bacillus subtilis BSP strain. Using conventional optimization techniques, physical parameters in submerged fermentation were adjusted at the shake flask level to reach 184 U/mL. These physicochemical parameters were further optimized by statistical surface response methodology using Box Behnken design, and the protease yield increased to 295 U/mL. The protease was purified and characterized biochemically. Both Ca²⁺ and Fe²⁺ increased the activity of the 36 kDa protease enzyme. Based on its strong inhibition by ethylenediaminetetracetate (EDTA), the enzyme was confirmed to be a metalloprotease. The protease was also resistant to various organic solvents (benzene, ethanol, methanol), surfactants (Triton X-100), sodium dodecyl sulfate (SDS), Tween 20, Tween-80 and oxidants hydrogen per oxide (H₂O₂). Characteristics, such as tolerance to high SDS and H₂O₂ concentrations, indicate that this protease has potential applications in the pharmaceutical and detergent industries.

Tribolium castaneum (Herbst) (Coleoptera: Tenebrionidae) is the most destructive pest of stored grain commodities. To control the attack of this insect pest, it is important to develop non-hazardous alternatives to replace fumigants. This study examined the fumigant toxicity and repellent activity of seven essential oils (Chinopodium ambrosiodes, Pinus roxburghii, Zanthoxylum armatum, Lepidium sativum, Azadirachta indica, Baccharis teindalensis, and Origanum majorana) against adult T. castaneum under controlled laboratory conditions. The fumigant toxicity and repellent activities of essential oils were tested using five different doses (62.5, 125, 250, 500, and 1000 µg) in vapour-phase fumigation and four-arm olfactometer bioassays, respectively. In vapor-phase fumigation bioassays, mortality data were recorded after 24, 48, and 72 h. The results showed that C. ambrosiodes and P. roxburghii essential oils are potential fumigants against adult T. castaneum. In repellency bioassays, a one-week-old adult population of T. castaneum was used to test the repellency potential of the essential oils. The results indicated that C. ambrosiodes and P. roxburghii had significant repellency potential against T. castaneum. Overall, we conclude that these essential oils have strong repellent and fumigant properties and can be used as potential repellent compounds to deter the insects.

Background: Ulcerative colitis is a chronic immune-mediated inflammatory bowel disease that involves inflammation and ulcers of the colon and rectum. To date, no definite cure for this disease is available.Objective: The objective of the current study was to assess the effect of Calliandra haematocephala on inflammatory mediators and oxidative stress markers for the exploration of its anti-ulcerative colitis activity in rat models of acetic acid-induced ulcerative colitis.Methods: Methanolic and n-hexane extracts of areal parts of the plant were prepared by cold extraction method. Phytochemical analysis of both extracts was performed by qualitative analysis, quantitative methods, and high-performance liquid chromatography (HPLC). Prednisone at 2 mg/kg dose and plant extracts at 250, 500, and 750 mg/kg doses were given to Wistar rats for 11 days, which were given acetic acid on 8th day through the trans-rectal route for the induction of ulcerative colitis. A comparison of treatment groups was done with a normal control group and a colitis control group. To evaluate the anti-ulcerative colitis activity of Calliandra haematocephala, different parameters such as colon macroscopic damage, ulcer index, oxidative stress markers, histopathological examination, and mRNA expression of pro and anti-inflammatory mediators were evaluated. mRNA expression analysis was carried out by reverse transcription quantitative real-time polymerase chain reaction (RT-qPCR).Results: The phytochemical evaluation revealed polyphenols, flavonoids, tannins, alkaloids, and sterols in both extracts of the plant. Results of the present study exhibited that both extracts attenuated the large bowel inflammation and prevented colon ulceration at all tested doses. Macroscopic damage and ulcer scoreswere significantly decreased by both extracts. Malondialdehyde (MDA) levels and nitrite/nitrate concentrations in colon tissues were returned to normal levels while superoxide dismutase (SOD) activity was significantly improved by all doses. Histopathological examination exhibited that both extracts prevented the inflammatory changes, cellular infiltration, and colon thickening. Gene expression analysis by RT-qPCR revealed the downregulation of pro-inflammatory markers such as tumor necrosis factor-alpha (TNF-α) and cyclooxygenase-2 (COX-2) whereas the anti-inflammatory cytokines including Interleukin-4 (IL-4) and Interleukin-10 (IL-10) were found to be upregulated in treated rats.Conclusion: It was concluded based on study outcomes that methanolic and n-hexane extracts of Calliandra haematocephala exhibited anti-ulcerative colitis activity through modulation of antioxidant defense mechanisms and the immune system. In this context, C. haematocephala can be considered as a potential therapeutic approach for cure of ulcerative colitis after bioassay-directed isolation of bioactive phytochemicals and clinical evaluation.