In tropical humid Africa, sandy soils in herbaceous savannas—often exposed to periodic burning—typically exhibit low carbon (C) content and nitrogen (N) availability. Savanna afforestation has the potential to improve soil functionality, but its effects remain underexplored. This study examines whether changes in soil micro-food web composition contribute to increased C and N cycling following afforestation. A 7-year experiment in Congo assessed Eucalyptus monocultures, N₂-fixing Acacia monocultures, and mixed Eucalyptus-Acacia plantations on former savanna landscapes. Soil attributes analyzed included organic C and N levels, pHH₂O, nitrate, ammonium, mineralization and nitrification rates, as well as bacteria, fungi, nematodes, and ammonia-oxidizing archaea (AOA) and bacteria (AOB) abundances in the top 10 cm of soil. Afforestation with Eucalyptus monocultures increased soil carbon by 1.7 times, net nitrogen mineralization rates by 1.9 times, and soil inorganic nitrogen levels by 2.5 times. Mixed Eucalyptus-Acacia and Acacia monocultures further enhanced nitrogen mineralization by 1.4 times and inorganic nitrogen by 2.3 times compared to Eucalyptus monocultures. These changes correlated with a progressive increase in AOA abundance, peaking in Acacia monocultures. Additionally, afforestation significantly boosted bacterial-feeding nematode abundance by 678%, while fungal-feeders, omnivores, and predators declined. Enhanced nitrogen cycling was positively linked to AOA and bacterial-feeding nematode abundances, emphasizing the necessity of monitoring micro-food web structures to better understand how land use changes shape soil biogeochemical cycles in tropical afforestation contexts.
Tag: bacteria
A phylogenetic census of global diversity of gut anaerobic fungi and a new taxonomic framework
Botryosphaeriaceae disease complex: a threat to baobab and marula in agroforestry systems in Kenya
Effects of Bacillus subtilis natto and Different Components in Culture on Rumen Fermentation and Rumen Functional Bacteria In Vitro
This study was to investigate the effects of live or autoclaved Bacillus subtilis natto, their fermented products and media on rumen fermentation and rumen functional bacteria in vitro. Rumen fluid from three multiparous lactating Holstein cows was combined and transferred into serum bottles after diluted. Fifteen serum bottles were divided into five treatments, which were designed as following: CTR (the fermentation of 0.5 g TMR and ruminal fluids from dairy cows), LBS (CTR plus a minimum of 1011 cfu live Bacillus subtilis natto), ABS (CTR plus a minimum of 1011 cfu autoclaved Bacillus subtilis natto), BSC (CTR plus 1 ml Bacillus subtilis natto fermentation products without bacteria), and BSM (CTR plus 1 ml liquid fermentation medium). When separated from the culture, live Bacillus subtilis natto individually increased the concentrations of ammonia-N (P < 0.01), MCP production (P < 0.01), and tended to elevate total VFA (P = 0.07), but decreased the ratio of acetate and propionate (P < 0.01). Autoclaved Bacillus subtilis natto has the similar function with the live bacteria except for the ratio of acetate and propionate. Except B. fibrisolvens, live or autoclaved Bacillus subtilis natto did not influence or decreased the 16S rRNA gene quantification of the detected bacteria. BSC and BSM altered the relative expression of certain functional bacteria in the rumen. These results indicated that it was Bacillus subtilis natto thalli that played the important role in promoting rumen fermentation when applied as a probiotic in dairy ration. © 2016, Springer Science+Business Media New York.
Sodium butyrate supplementation impacts the gastrointestinal bacteria of dairy calves before weaning
The objective of this study was to systematically investigate how sodium butyrate (SB) affects the gastrointestinal bacteria in newborn calves at different stages before weaning. Forty female newborn Holstein calves (4-day-old, 40 ± 5 kg of body weight) were randomly divided into four groups; each group was supplemented with four SB doses: 0, 15, 30, and 45 g/day (ten replicates) in SB0, SB15, SB30, and SB45 groups, respectively. SB was fed with milk replacer from day 4 to day 60. Rumen fluid and feces were collected on days 2, 14, 28, 42, and 60 for 16S rRNA high-throughput sequencing. Data were analyzed in a complete randomized design and analyzed on the online platform of Majorbio Cloud Platform. The results showed that SB significantly increased the α-diversity in feces, especially Shannon and Chao indices in SB45 and SB30 at day 60 more than in SB15 (P < 0.05). Additionally, SB significantly enhanced Firmicutes growth from day 2 to 28 and also increased Bacteroides abundance from day 28 to 42 in rumen and feces (P < 0.05). SB also significantly inhibited Proteobacteria abundance in rumen and feces during the study period (P < 0.05). SB also promoted some potential beneficial bacterial abundance, including Prevotella, Lachnospiraceae, Clostridium, Ruminococcus, and Muribaculaceae (P < 0.05). Additionally, Escherichia-Shigella abundance at SB0 was significantly lower than in the other groups (P < 0.05). In conclusion, this study firstly reported a dynamic curve showing of the SB effects on bacteria in calves before weaning. This study provides valuable evidence for the development of the gastrointestinal tract of the calves in the early stage of the life. SB supplementation improved the gastrointestinal health by regulating the bacterial populations. Key points: • The gastrointestinal tract of calves has been improved after the SB supplementation. • Microbes were the vital influential factor in the development of calves. • Intervention before weaning is an effective strategy for calf health.