3.2 Bacterial diversity between the two sexes
Bacterial community richness and diversity varied between female and
male of P . astrigera (Table 1). The results of Student’st -test showed that bacterial α-diversity of Sobs (P< 0.05), Chao1 (P < 0.05) and Shannon index
(P < 0.001) in female were significantly lower than
male, whereas,
Simpson
index in female was significantly higher than male (P <
0.05). Meanwhile, male showed a much larger standard deviation in Sobs
and Chao1 indices than female.
The
PCoA results of β-diversity illustrated that
bacterial community of the two
different sex groups
clustered
independently. The results of Adonis test showed significant difference
between female and male (P < 0.05,R 2 = 0.48; Figure 1) proving that the community
composition and their relative abundance were distinct differences
between the two sex groups, and the variation range between male is much
greater than that of female.
3.3 Bacterial compositionsbetween
the two sexes
The relative abundances of dominant (> 1%) gut bacteria
showed apparent differences between two sexes at different taxon levels
(Figure 2). At phylum level, a total of 21 phyla were identified across
all data, among which,
Actinobacteriota,
Firmicutes
and
Proteobacteria
were the dominant phyla in both two sexes, in addition, Cyanobacteria
and Bacteroidetes were dominant in male (Figure 2a).
The results of Wilcoxon rank-sum test
indicated that female had a significantly higher relative abundance of
Actinobacteriota and a significantly lower relative abundance of
Firmicutes relative to male (P < 0.05; Figure 3a).
Other
phyla were all higher in male than female, though no significant
difference. At genus level, a total of 168 genera were found across all
data,
among
which 5 dominant genera belong to female, whereas 12 dominant genera
belong to male (Figure 2b). The results of Wilcoxon rank-sum test showed
that
female
had a significantly higher relative abundance of Rhodococcus and
significantly lower relative abundance of Acinetobacter ,Ruminococcus and Fusicatenibacter relative to male
(P < 0.05; Figure 3b). All
other
genera had no significant difference between the two sexes.
In agreement with composition analysis, noteworthy changes in bacterial
community were found from the result of LEfSe analysis between female
and male, based on relative abundance of biomarkers of bacteria (LDA
Score > 4, P < 0.05; Figure 4a, b). In
female, two groups of bacteria were significantly enriched,
namelyRhodococcus (from phylum to genus),norank_f_norank_o_0319-6G20 (from class to genus). In male,
two groups of bacteria were
significantly
enriched, namely Blautia (from phylum to genus),Lactobacillus(the
phylum and family to genus).