Background: Medical plants confer various benefits to human health and their bioconversion through microbial fermentation can increase efficacy, reduce toxicity, conserve resources and produce new chemical components. In this study, the cholesterol-lowering monacolin K genes and content produced by Monascus species were identified. The high-yield monacolin K strain further fermented with various medicinal plants. The antioxidant and anti-inflammatory activities, red pigment and monacolin K content, total phenolic content, and metabolites in the fermented products were analyzed. Results: Monacolin K was detected in Monascus pilosus (BCRC 38072), and Monascus ruber (BCRC 31533, 31523, 31534, 31535, and 33323). It responded to the highly homologous mokA and mokE genes encoding polyketide synthase and dehydrogenase. The high-yield monacolin K strain, M. ruber BCRC 31535, was used for fermentation with various medicinal plants. A positive relationship between the antioxidant capacity and total phenol content of the fermented products was observed after 60 days of fermentation, and both declined after 120 days of fermentation. By contrast, red pigment and monacolin K accumulated over time during fermentation, and the highest monacolin K content was observed in the fermentation of Glycyrrhiza uralensis, as confirmed by RT-qPCR. Moreover, Monascus-fermented medicinal plants including Paeonia lactiflora, Alpinia oxyphylla, G. uralensis, and rice were not cytotoxic. Only the product of Monascus-fermented G. uralensis significantly exhibited the anti-inflammatory capacity in a dose-dependent manner in lipopolysaccharide-induced Raw264.7 cells. The metabolites of G. uralensis with and without fermentation (60 days) were compared by LC/MS. 2,3-Dihydroxybenzoic acid, 3,4-dihydroxyphenylglycol, and 3-amino-4-hydroxybenzoate were considered to enhance the antioxidant and anti-inflammatory ability. Conclusions: Given that highly homologous monacolin K and citrinin genes can be observed in Monascus spp., monacolin K produced by Monascus species without citrinin genes can be detected through the complementary methods of PCR and HPLC. In addition, the optimal fermentation time was important to the acquisition of antioxidants, red pigment and monacolin K. These bioactive substances were significantly affected by medicinal plants over fermentation time. Consequently, Monascus-fermented G. uralensis had a broad spectrum of biological activities.

Rice paddies are a major source of agricultural greenhouse gas emissions, primarily caused by the proliferation of anaerobic, methanogenic bacteria during prolonged inundation. Phototrophic bacteria utilize light energy for metabolism and are potential candidates for carbon and nitrogen fixation, and reduction of methane gas emissions. We investigated the effect of applying the phototrophic bacterium Rhodopseudomonas palustris (PNSB) during the cropping period on soil organic carbon (SOC) and methane emissions for second-crop rice in the Tainan Guantian region. In the experimental group, PNSB was applied five times during the rice cultivation period. Compared to the control group, the experimental group demonstrated a significant reduction in methane emissions, especially in the tillering stage, where emissions averaged 37.26 ± 12.97 g-CH₄/m²/season compared to 49.48 ± 25.06 g-CH₄/m²/season of the control group. Over the entire growing season, the experimental group reduced the emission of 3.05 Mg·CO₂e/ha. Additionally, administering PNSB improved soil carbon sequestration, from 4.89 tons-C/ha in the control group to 17.45 tons-C/ha. The phototrophic bacterium PNSB was beneficial for soil carbon sequestration and reducing greenhouse gas emissions. However, further research is required to optimize the methodology of applying phototrophic bacteria for agricultural purposes.

With the acceleration of climate change in recent years, enhancing the carbon sequestration capacity of agricultural soil has become an important strategy for achieving sustainable agriculture and carbon neutrality. This study aimed to investigate the effects of multiple experimental factors on the soil carbon fixation efficiency of corn cultivation using the Taguchi method of experimental design. The following factors were investigated: amount of fertilizer, amount of irrigation, as well as soil supplementation with Rhodopseudomonas sp. strain AKW01 and Rhodoplanes sp. strain AKW02. We designed an L9(3⁴) orthogonal array with three levels for each factor, and conducting nine sets of experimental plantings for each element in the array. Various outcomes were measured during different growth stages, including soil pH, soil electrical conductivity, soil organic carbon (SOC); as well as the height, chlorophyll content as determined using a Soil Plant Analysis Development (SPAD) meter, fresh weight, and dry weight of plant matter. The results of this study showed that the addition of the AKW01 strain significantly improved crop growth and carbon sequestration and was the primary factor affecting crop performance among the experimental factors studied, with a total variance contribution of 41.55%. Another significant factor was irrigation water amount, with a total variance contribution of 35.78%. Crop performance was optimal when the addition of the AKW01 strain was at 10 mL/plant, which led to a mean height of 138.1 cm, SPAD of 29.8, SOC increase of 0.01%, and fresh and dry weights of 95.38 g and 48.03 g, respectively.

Background/Objectives: Esterases are widely used in various industrial fields. This study aimed to isolate and characterize esterase genes from Laceyella sacchari HS49-1, a thermophilic bacterium from a hot spring, which can survive at 45–60 °C and pH 5-10 with robust esterase activity. Methods: A genomic shotgun library was constructed to identify three esterase genes: two in family XII (Est2 and Est7) and one in family VIII (Est1). Sequence analysis revealed significant divergence from other genera. Only Est1 was successfully expressed in Escherichia coli. Its activity, optimal conditions, thermostability, and structure were investigated using p-NP butyrate, temperature/pH assays, heating pre-treatment, and fluorescence quenching. Results: Est1 demonstrated high activity (57.43 ± 0.04 U/mg) towards short-chain p-NP butyrate (C4). Molecular-docking analyses revealed that Est1’s catalytic motif (GXSXG) interacts with various p-NP esters, with binding energy and interaction types varying by acyl chain length. The optimal temperature was 60 °C, and the optimal pH was 8. Est1 exhibited excellent thermostability, retaining 90% of its activity after pre-treatment at 50 °C for 8 h and 69.8% after pre-treatment at 80 °C for the same duration. Fluorescence quenching showed that after 1 h at 80 °C, the fluorescence was reduced by only 16.6%, indicating remarkable heat resistance. Additionally, Est1 did not require metal ions as cofactors and maintained 74.8% of its activity in the presence of 0.1% SDS. Conclusions: The unique properties of Est1 from L. sacchari HS49-1 highlight its potential for industrial applications. Further exploration of this thermophilic bacterium could uncover more valuable genes.