Intensive potato continuous cropping (IPCC) results in low
potato yields compared with non-intensive potato continuous
cropping (PCC) and potato-maize rotation (PMRC). However,
it is still unclear whether the degree of potato continuous cropping
obstacle is related to the soil environment formed by the
previous crop. To investigate the effect of planting potatoes
and planting maize after harvesting the spring potatoes on
soil chemical properties and soil microbial community structure,
an experiment was carried out in the same origin soil
environment over a period of seven years: (a) PCC, i.e., spring
planting; (b) IPCC, i.e., autumn and spring planting (IPCC);
(c) PMRC, i.e., spring potatoes and summer maize (PMRC),
and (d) fallow (CK). We confirmed that the potato yield under
PMRC was significantly higher than that under PCC and
IPCC. Under IPCC, soil total phosphorus content was significantly
higher than other treatments, whereas ammonium
nitrogen content was the lowest. Compared with PCC and
IPCC, PMRC had a higher ammonium nitrogen content and
lower total phosphorus content. The significantly different
fungal taxa in IPCC (Glomerellales, Plectosphaerella, Thelebolales)
may threaten the health of the plant and positive correlated
with soil total phosphorus, while other microbial taxa
in PMRC (Bacillales, Polythrincium, Helotiales) can mainly
promotes plant nitrogen uptake and protects plants against
diseases. The PMRC-promoting taxa were positively correlated
with the ammonium nitrogen content and negative correlated
with soil total phosphorus content. In summary, the
cropping systems might have affected potato yields by changed
soil microorganism community structures – especially fungal
community structures – and by the chemical properties of the
soils that also depends on microbes.
Escherichia coli (E. coli) infection is very common among
young growing animals, and zinc supplementation is often
used to alleviate inflammation induced by this disease. Therefore,
the objective of this study was to evaluate whether chitosan-
chelated zinc (CS-Zn) supplementation could attenuate
gut injury induced by E. coli challenge and to explore how CSZn
modulates cecal microbiota and alleviates intestinal inflammation
in weaned rats challenged with E. coli. 36 weaned
rats (55.65 ± 2.18 g of BW, n = 12) were divided into three
treatment groups consisting of unchallenged rats fed a basal
diet (Control) and two groups of rats challenged with E. coli
and fed a basal diet or a diet containing 640 mg/kg CS-Zn
(E. coli + CS-Zn, containing 50 mg/kg Zn) for a 14-day experiment.
On days 10 to 12, each rat was given 4 ml of E. coli
solution with a total bacteria count of 1010 CFU by oral gavage
daily or normal saline of equal dosage. CS-Zn supplementation
mitigated intestinal morphology impairment (e.g.
higher crypt depth and lower macroscopic damage index)
induced by E. coli challenge (P < 0.05), and alleviated the increase
of Myeloperoxidase (MPO) activity after E. coli challenge
(P < 0.05). 16S rRNA sequencing analyses revealed that
E. coli challenge significantly increased the abundance of Verrucomicrobia
and E. coli (P < 0.05). However, CS-Zn supplementation
increased the abundance of Lactobacillus and decreased
the relative abundance of Proteobacteria, Desulfovibrio
and E. coli (P < 0.05). The concentrations of butyrate in
the cecal digesta, which decreased due to the challenge, were
higher in the E. coli + CS-Zn group (P < 0.05). In addition,
CS-Zn supplementation significantly prevented the elevation
of pro-inflammatory cytokines IL-6 concentration and upregulated
the level of anti-inflammatory cytokines IL-10 in
cecal mucosa induced by E. coli infection (P < 0.05). In conclusion,
these results indicate that CS-Zn produces beneficial
effects in alleviating gut mucosal injury of E. coli challenged
rats by enhancing the intestinal morphology and modulating
cecal bacterial composition, as well as attenuating inflammatory
response.