4.2. ANCOM analysis
In an early report, bacterial members belonging to the Gammaproteobacteria followed by members of Alphaproteobacteria were observed to be dominant in Calanus finmarchicus[10]. But, in the present ANCOM analysis, the high percentile of Gamma and Alphaproteobacteria were equal in number (three genera each) in Calanus spp. (Figure 3). Similar to our results, the unclassified genus of Rhodobacteraceae was reported to be abundant in Acartia longiremis [10]. Colwelliaceae was reported to be abundant in Calanus finmarchicus[10], but, in the present analysis, order Colwelliaceae was found to be in high percentile inCentropages sp. An abundance of Flavobacteriaceae was observed along with phytoplankton and diatoms in the gut ofCalanus finmarchicus with food [2] whereasSedinimicola sp. (Flavobacteriaceae) was observed to be dominant in Acartia longiremis ., Calanus finmarchicus and Centropageshamatus [10]. Also, Dorosz et al.[48] reported that Flavobacterium was more dominant in Temora longicornis than Acartia tonsa , whereas, in our case, Flavobacteriaceae was found to be in high percentile in Calanus spp.. On comparing, the present ANCOM analysis and previous reports, Pseudoalteromonas sp. appeared in high percentile not only within Centropages sp. and inCentropages sp. [10] but also consistent and abundant bacteria in Acartia sp., and Calanus sp.[10]. As for as, the prevalence ofPseudomonas has been observed in Pleuromamma spp.[11], whereas this was not the case in our analysis (Figure 3). Similarly, Cregeen [11]analysed the bacteriobiome of Pleuromamma sp. and observed the dominance of Alteromonas , but, from our meta-analysis, a high abundance of Alteromonas was observed in Centropages sp. when compared to five other genera including Pleuromamma spp. (Figure 3).
From our analysis, Nitrosopumilus was observed to be high inTemora spp., but the Nitrosopumilus abundance was reported to have no difference between the particle-associated in the water column and within Temora spp. [38], so the high percentile observed in our analysis may be due to the exchange ofNitrosopumilus from seawater. The Vibrionales was identified as a core member in the gut of Pleuromamma spp.[1], which is similar to the present analysis, i.e. Vibiro percentile was found to be high in the CAB ofPleuromamma spp. The copepods were reported to have a selective niche of Vibrio that had capability of degrading chitin[1, 49]. In the present analysis, seven bacterial taxa were found to be in high percentile in Centropages sp. and, among those seven, four taxa belong to the Gammaproteobacteria. A high proportion of Gammaproteobacteria in Centropages sp. was also reported earlier [10].