Publications

4374

AbstractBACKGROUNDThe brown marmorated stink bug Halyomorpha halys has become an invasive insect pest of many crops. A promising control strategy to manage the proliferation of H. halys is based on the suppression of its obligate and vertically transmitted uncultivated symbiotic bacterium Candidatus Pantoea carbekii through surface‐sterilization of H. halys eggs. Indeed, the application of antimicrobial formulations on the eggs of H. halys could cause mortality of endosymbiont and consequently of newly emerged nymphs.In this study, a microbial live/dead assay was applied directly on H. halys eggs to evaluate Ca. P. carbekii loss of viability after treatments with seven commercial formulations including fungicides (copper hydroxide, sulphur, sweet orange essential oil) and plant biostimulants (flavonoids and chestnut tannin extract) compared with two disinfectants for civil and industrial use (sodium hypochlorite/hydrated sodium/tetraborate decahydrate and peracetic acid/hydrogen peroxide). Impact of mode of application was also evaluated, as surface treatment of egg masses was performed through spraying and dipping in laboratory conditions. Antimicrobial activity data were finally complemented with observations of egg hatching and vitality of the nymphs.RESULTSThe optimization of live/dead staining is useful for evaluating Ca. P. carbekii mortality directly on eggs, providing a rapid and reliable culture‐independent approach. Sodium hypochlorite, copper, sulphur, tannins and sweet orange essential oil showed an antimicrobial effect against Ca. P. carbekii and a H. halys egg hatching reduction and nymph's vitality.CONCLUSIONSThe antimicrobial and insecticidal effects of these commercial products should be further studied to assess their in‐field efficiency as well as the impact of these substances on non‐target organisms. The approach followed in this study could be considered a robust pipeline of analyses to evaluate the effectiveness of antimicrobial eco‐friendly compounds in symbiotic control of H. halys. © 2024 Society of Chemical Industry.

Opinion 131 addresses a Request for an Opinion asking the Judicial Commission to conserve the genus name Proteus Hauser 1885 (Approved Lists 1980) over its earlier homonym, the protozoan genus name Proteus Müller 1786. The Judicial Commission agrees that the later homonym is illegitimate and that the replacement of the prokaryotic name Proteus would be undesirable. It is also concluded that Proteus Müller 1786 is an objectively invalid name under the International Code of Zoological Nomenclature. Judicial Opinions 9, 12 and 130 serve as precedents for the conservation of Proteus Hauser 1885 (Approved Lists 1980) over Proteus Müller 1786. This action is taken here and makes the prokaryotic name Proteus legitimate.

The anammox bacteria “Candidatus Kuenenia stuttgartiensis” (Ca. Kuenenia) are able to gain energy by combining ammonium and nitrite to produce nitrogen gas, which is an ecologically and technically significant activity process. In this reaction, nitric oxide serves as a recognized intermediate in the reduction of nitrite, which is subsequently combined with ammonium to produce hydrazine. However, the enzyme that converts nitrite to nitric oxide remains elusive. In this study, we investigated the nitrite-reducing activity in “Ca. Kuenenia stuttgartiensis” strain CSTR1 to identify candidates for such an enzyme. An optimized in vitro assay was established to measure nitrite-reducing activities, with which we followed the activity in protein fractions obtained from various fractionation methods. Separation of the cell extract of strain CSTR1 with size exclusion chromatography yielded active fractions corresponding to a molecular size range of 150–200 kDa. Several proteins coeluted with the nitrite-reducing activity, including the hydroxylamine dehydrogenase HOX, an NADP-dependent isopropanol dehydrogenase (Adh), an electron-transfer 4Fe-4S subunit protein (Fcp), and a nitric oxide detoxifying flavorubredoxin (NorVW). However, further separation of the cell extract with anion exchange chromatography, resulted in much lower activity yields, and activities were distributed among several fractions. In addition, fractionation of cell extracts using ultracentrifugation and ultrafiltration linked the activity to HOX, but could not exclude the involvement of other proteins in the activity. Overall, our results suggest that the molecular mechanism for nitrite reduction in “Ca. Kuenenia” strains is more complex than that currently described in the literature. Nitrite reduction appears to be strongly associated with HOX but may additionally require the participation of other proteins.

A novel, strictly aerobic, non-motile, and pink-pigmented bacterium, designated 7Alg 153T, was isolated from the Pacific green alga Cladophora stimpsonii. Strain 7Alg 153T was able to grow at 4–32 °C in the presence of 1.5–4% NaCl and hydrolyze L-tyrosine, gelatin, aesculin, Tweens 20, 40, and 80 and urea, as well as produce catalase, oxidase, and nitrate reductase. The novel strain 7Alg 153T showed the highest similarity of 96.75% with Pseudaestuariivita rosea H15T, followed by Thalassobius litorarius MME-075T (96.60%), Thalassobius mangrovi GS-10T (96.53%), Tritonibacter litoralis SM1979T (96.45%), and Marivita cryptomonadis CL-SK44T (96.38%), indicating that it belongs to the family Roseobacteraceae, the order Rhodobacteales, the class Alphaproteobacteria, and the phylum Pseudomonadota. The respiratory ubiquinone was Q-10. The main polar lipids were phosphatidylethanolamine, phosphatidylglycerol, diphosphatidylglycerol, phosphatidylcholine, two unidentified aminolipids, and one unidentified lipid. The predominant cellular fatty acids (>5%) were C18:1 ω7c, C16:0, C18:0, and 11-methyl C18:1 ω7c. The 7Alg 153T genome is composed of a single circular chromosome of 3,786,800 bp and two circular plasmids of 53,157 bp and 37,459 bp, respectively. Pan-genome analysis showed that the 7Alg 153T genome contains 33 genus-specific clusters spanning 92 genes. The COG20-annotated singletons were more often related to signal transduction mechanisms, cell membrane biogenesis, transcription, and transport, and the metabolism of amino acids. The complete photosynthetic gene cluster (PGC) for aerobic anoxygenic photosynthesis (AAP) was found on a 53 kb plasmid. Based on the phylogenetic evidence and phenotypic and chemotaxonomic characteristics, the novel isolate represents a novel genus and species within the family Roseobacteraceae, for which the name Algirhabdus cladophorae gen. nov., sp. nov. is proposed. The type strain is 7Alg 153T (=KCTC 72606T = KMM 6494T).