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Applying microbial organic fertilizer (MOF) effectively improves soil tilth and microbial diversity. However, there were few studies about the changes incurred in the physicochemical properties and bacterial diversity in the farmland of North China at a large-scale following MOF application. This study aimed to investigate the soil physicochemical properties and bacterial community following MOF application. A total of 910 t MOF was used on 173 hectares of degraded soil, and the results indicated increased nutrients in the top plough layer. Compared to controls, the treated samples had significant higher organic matter, total nitrogen, available phosphorus, potassium, and hydrolyzed nitrogen (p < 0.05). Furthermore, MOF application also induced a slight increase in the soil bacterial richness, but a significant decrease in the evenness was observed, where Firmicutes, Actinobacteria, and Bacteroidetes were enriched in the treated group, with Bacillus and Arthrobacter being the dominant genera, accounting for 0.291 and 0.136, respectively. Similarly, an increase in the proportion of Pseudomonas and Psychrobacillus was also observed at up to 0.038 and 0.034, respectively. The MOF treatment improved complex carbon metabolism and nitrogen reduction functions, inhibiting nitrogen oxidation as represented by nitrification. Redundancy and correlation analyses showed that total nitrogen, available phosphorus, and pH were the main factors driving the soil microbial community. This study concluded that MOF application could improve the soil's physicochemical properties and enhance the abundance and function of soil microbes, which is an effective method for improving the soil tilth and ecology of farmland in north China. [ABSTRACT FROM AUTHOR]

Erythromycin pollution is an important risk to the ecosystem and human health worldwide. Thus, it is urgent to develop effective approaches to decontaminate erythromycin. In this study, we successfully isolated a novel erythromycin-degrading fungus from an erythromycin-contaminated site. The erythromycin biodegradation characteristics were investigated in mineral salt medium with erythromycin as the sole carbon and energy source. The metabolites of erythromycin degraded by fungus were identified and used to derive the degradation pathway. Based on morphological and phylogenetic analyses, the isolated strain was named Curvularia sp. RJJ-5 (MN759651). Optimal degradation conditions for strain RJJ-5 were 30°C, and pH 6.0 with 100 mg L−1 erythromycin substrate. The strain could degrade 75.69% erythromycin under this condition. The following metabolites were detected: 3-depyranosyloxy erythromycin A, 7,12-dyhydroxy-6-deoxyerythronolide B, 2,4,6,8,10,12-hexamethyl-3,5,6,11,12,13-hexahydroxy-9-ketopentadecanoic acid and cladinose. It was deduced that the erythromycin A was degraded to 3-depyranosyloxy erythromycin A by glycoside hydrolase in the initial reaction. These results imply that Curvularia sp. RJJ-5 is a novel erythromycin-degrading fungus that can hydrolyze erythromycin using a glycoside hydrolase and has great potential for removing erythromycin from mycelial dreg and the contaminated environment. [ABSTRACT FROM AUTHOR]

The residual erythromycin in fermentation waste can pollute the environment and threaten human health. However, there are no effective approaches to remedy this issue. In this study, an erythromycin‐degrading bacterium named RJJ‐61 was isolated and identified as a strain of Delftia lacustris based on morphological and phylogenetic analyses. The degradation ability of this strain was also evaluated; it could degrade 45.18% of erythromycin at 35°C in 120 h. Furthermore, the key degradation gene ereA was cloned from strain RJJ‐61 and expressed in Escherichia coli BL21; the molecular weight of the expressed protein was ~45 kDa. The enzyme activity of EreA was 108.0 mU ml−1 at 35°C and pH 7.0. Finally, the EreA protein was used to degrade erythromycin from mycelial dregs and 50% diluted solution, and the removal rates in them were 41.42% and 69.78%, respectively. In summary, D. lacustris RJJ‐61 is a novel erythromycin‐degrading strain that has great potential to remove erythromycin pollutants from the environment. [ABSTRACT FROM AUTHOR]

The objective of this study was to gain deeper insights into chemical transformations and the clostridial community dynamics during the ensiling of alfalfa. A factorial experiment was conducted with four alfalfa cultivars [Sanditi (A1), AC Caribou (A2), WL319HQ (A3) and 4030 (A4)]three wilting durations [0 h (direct-cut), 2 h and 4 h]three storage periods (14, 28 and 56 days). The clostridial community was examined using denaturing gradient gel electrophoresis. High butyric acid and ammonia nitrogen (NH3-N) contents and clostridia numbers were observed in direct-cut silage, with higher values observed in A4 than in the other three cultivars. However, butyric acid and NH3-N contents and clostridia numbers decreased with wilting regardless of the cultivar. Although Clostridium ghonii and Clostridium sartagoforme were common to all direct-cut and wilted silages, bands for these species were faint. Differences in the appearing time of these species were observed, bands for C. ghonii were found after 14 and 28 days of ensiling, while those for C. sartagoforme were only found after 56 days. In addition, in direct-cut silage, distinct bands for Clostridium perfringens were detected in A1, A2 and A3, while those for Clostridium sporogenes were detected in A4. The inactive spores of clostridia could be observed in 4-h wilted silage as no butyric acid was detected. It was concluded that the enhanced clostridial fermentation of direct-cut silage was attributed mainly to C. perfringens and C. sporogenes, while C. ghonii and C. sartagoforme were involved in the restricted clostridial fermentation of 2-h wilted silage. [ABSTRACT FROM AUTHOR]

Oils in food waste can pollute the environment and negatively affect human health. Biodegradation is a promising method for disposing of waste edible oils. In this study, an oil-degrading bacterium was isolated from kitchen waste for efficient degradation of edible oils. Its growth and oil degradation characteristics were investigated in basic salt medium with edible oils as the sole carbon and energy source; the triacylglycerol lipase gene (EC 3.1.1.3) was cloned and expressed in Escherichia coli. A novel oil-degrading bacterium assigned as IUMR B67 was successfully isolated. Morphological and molecular analyses revealed that strain IUMR B67 belongs to Kosakonia cowanii. After 144 h of incubation, the oil degradation rate at 37°C was 95.80%. Optimal conditions for IUMR B67 were recorded at 37°C and 0.1% NaCl with 0.1% ammonium sulfate supplementation. The lipase gene of strain IUMR B67 was determined to be 912 base pairs, and the lipase activity of the expressed protein was 3.02 U/mL, which was significantly higher than the control (P  < 0.05). Overall, Kosakonia cowanii IUMR B67 is a novel edible oil-degrading strain that can hydrolyze oil via its lipase activity, which may be useful in the disposal of oils and oily food waste. [ABSTRACT FROM AUTHOR]