Modestobacter lacusdianchii sp. nov., a Phosphate-Solubilizing Actinobacterium with Ability to Promote Microcystis Growth

Abstract

A novel actinobacterium, designated strain JXJ CY 19T, was isolated from a culture mat of Microcystis aeruginosa FACHB-905 collected from Dianchi Lake, South-west China. 16S rRNA gene sequences comparison of strain JXJ CY 19T and the available sequences in the GenBank database showed that the strain was closely related to Modestobacter marinus 42H12-1T (99.1% similarity) and Modestobacter roseus KLBMP 1279T (99.0%). The isolate had meso-diaminopimelic in the cell wall with whole-cell sugars of mannose, rhamnose, ribose, glucose, galactose, and arabinose. The menaquinone detected was MK-9(H4), while the major cellular fatty acids include C17:1 ω8c, C15:0 iso, C15:1 iso G and C16:0 iso. The polar lipids were diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylinositol, phosphatidylinositol mannoside and an unidentified phospholipid. The DNA-DNA hybridization values between strains JXJ CY 19T and the closely related type strains Modestobacter marinus CGMCC 4.5581T and Modestobacter roseus NBRC 108673T were determined to be 50.8 ± 0.8% and 44.1 ± 1.7%, respectively. The DNA G+C content was 71.9 mol%. On the basis of the above taxonomic data and differences in physiological characters from the closely related type strains, strain JXJ CY 19T was recognized as a novel species of the genus Modestobacter, for which the name Modestobacter lacusdianchii sp. nov. (JXJ CY 19T = KCTC 39600T = CPCC 204352T) is proposed. The type strain JXJ CY 19T can solubilize calcium phosphate tribasic (Ca3(PO4)2), phytin and L-α-phosphatidylcholine. The phosphate-solubilizing property of the novel actinobacterium could be a possible factor for the increase in growth of Microcystis aeruginosa FACHB-905 in ecosystem where the amount of available soluble phosphate is limited such as Dianchi Lake.

Mycolicibacterium lacusdiani sp. nov., an Attached Bacterium of Microcystis aeruginosa

“…Attached bacteria of high cell densities probably compete with Maf for nutrients, which may further inhibit the growth of Maf over a period of time. However, the inhibition ratio decreased with the culture time and the decreasing cell density of the bacteria ( Figure 3 ; Table 2 ), similar to other reports (Zhang et al, 2016a , b ). The results ( Tables 2 , 3 ) showed that the cell density of strain JXJ CY 35 T could be maintained at about 10 5 CFU/ml in cocultures with Maf regardless of the initial inoculation dosages of the bacteria.…”

“…Our study indicated that strain JXJ CY 35 T can release available phosphate from both organic and inorganic insoluble P, which is consistent with its gene annotation from GO database ( Supplementary Table S3 ). Therefore, similar to other attached bacteria (Yang and Xiao, 2011 ; Zhang et al, 2016a , b , 2017 ), strain JXJ CY 35 T could dissolve insoluble tricalcium phosphate, and further provided Maf with available phosphate for growth in the absence of available P ( Table 3 ). Strain JXJ CY 35 T can grow in the nitrogen-free medium, indicating that it has N fixing activity and can convert N 2 into NH 3 .…”

“…High inoculation dosages of strain JXJ CY 35 T could inhibit the growth of Maf ( Figure 3 ), similar to Pseudomonas sp. X (Yang and Xiao, 2011 ), Modestobacter lacusdianchii JXJ CY 19 T (Zhang et al, 2016a ), and Citricoccus lacusdiani JXJ CY 21 T (Zhang et al, 2016b ). Attached bacteria of high cell densities probably compete with Maf for nutrients, which may further inhibit the growth of Maf over a period of time.…”

“…Ma is the dominant bloom-forming species in Lake Dianchi (Liu, 1999 ). In our previous studies, many attached bacteria, including three novel species (Zhang et al, 2016a , b , 2017 ), were isolated from the culture mass of Ma isolated from Lake Dianchi (Guo et al, 2020 ). In this study, another novel actinobacterium strain JXJ CY 35 T , belonging to the genus Mycolicibacterium , was isolated from the culture mass of M. aeruginosa FACHB 905 (Maf), which was isolated from the Microcystis water bloom sample collected from Lake Dianchi.…”

Properties of Modestobacter deserti sp. nov., a Kind of Novel Phosphate-Solubilizing Actinobacteria Inhabited in the Desert Biological Soil Crusts

“…The ability of these three strains and the reference strains M. lapidis DSM 100206 T and M. multiseptatus DSM 44406 T to solubilize insoluble phosphate were determined on plates using phosphate-solubilizing media and confirmed using broth culture method (Zhang et al, 2016), with little modification addressed as follows.…”