Abstract
The biodiversity of phototrophic purple nonsulfur bacteria (PNSB) in comparison with purple sulfur bacteria (PSB) in colored blooms and microbial mats that developed in coastal mudflats and pools and wastewater ditches was investigated. For this, a combination of photopigment and quinone profiling, pufM gene-targeted quantitative PCR, and pufM gene clone library analysis was used in addition to conventional microscopic and cultivation methods. Red and pink blooms in the coastal environments contained PSB as the major populations, and smaller but significant densities of PNSB, with members of Rhodovulum predominating. On the other hand, red-pink blooms and mats in the wastewater ditches exclusively yielded PNSB, with Rhodobacter, Rhodopseudomonas, and/or Pararhodospirillum as the major constituents. The important environmental factors affecting PNSB populations were organic matter and sulfide concentrations and oxidation–reduction potential (ORP). Namely, light-exposed, sulfide-deficient water bodies with high-strength organic matter and in a limited range of ORP provide favorable conditions for the massive growth of PNSB over co-existing PSB. We also report high-quality genome sequences of Rhodovulum sp. strain MB263, previously isolated from a pink mudflat, and Rhodovulum sulfidophilum DSM 1374T, which would enhance our understanding of how PNSB respond to various environmental factors in the natural ecosystem.
Highlights
The phototrophic purple bacteria are widely distributed in nature and play important roles in global carbon, nitrogen, and sulfur cycles
Rhodovulum (Rdv.) strictum and some other marine purple nonsulfur bacteria (PNSB) related to Rhv. sulfidophilum were isolated from colored blooms in coastal mudflats and tide pools [20,21]
To know about environmental factors affecting PNSB populations in blooming phenomena, we investigated the relationships between viable PNSB counts and sulfide concentrations, oxidation–reduction potential (ORP), or Moircgroaorngiacnismmas t2t0e2r0, c8o, 1n5c0entrations expressed as Chemical oxygen demand (COD)
Summary
The phototrophic purple bacteria are widely distributed in nature and play important roles in global carbon, nitrogen, and sulfur cycles. Okubo et al [19] reported that a swine wastewater ditch allowed PNSB to exclusively develop into red microbial mats This massive development was possibly achieved under specific conditions characterized by the exposure to light and air, the presence of high-strength organic acids, and the absence of sulfide. Rhodovulum (Rdv.) strictum and some other marine PNSB related to Rhv. sulfidophilum were isolated from colored blooms in coastal mudflats and tide pools [20,21] These previous reports suggest the potential of PNSB to naturally develop massive populations under particular conditions, it is still uncertain how many PNSB populations co-exist with PSB in natural blooming communities and what the factors are that allow for the massive growth of PNSB in the environment
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
