Hey readers 👋

Today is a special edition because this week we celebrate International Microorganism Day! So before getting into the news, I wanted to share something a little more personal in the editor's note.

Also along this theme, this week we are letting the microorganisms take center stage:

Let's dive in!

I have been sending this newsletter for a little while now, but I have never properly introduced myself! My name is Lina, and this is me at ten years old, playing with a microscope. I was already fascinated by the small world that most people cannot see, and years later that curiosity brought me to a career in microbiology. That microscope eventually led to a world of serial dilutions, experiments, standardizations, fermentations, PCR assays and quality control procedures!

Over the years, working with microorganisms has brought me a great deal of satisfaction. It has shown me how much the profession I chose can contribute to different industries, although I found my place in agriculture, the field I find most interesting.

In agriculture, that invisible world is present in the soil, around plant roots and on every crop. Microorganisms influence nutrient availability, plant health, disease and crop protection, and there is still so much to understand about new strains, interactions, antagonisms, compounds, symbioses, synergies and metabolites that may lead to useful discoveries.

Of course, the work can also bring frustration, long days, a few tears and probably a few grey hairs 🤣. Anyone who has worked in a laboratory knows how much effort can sit behind a single result: repeating an experiment because one control failed, starting a standardization again, waiting for a fermentation or trying to understand why something that worked yesterday did not work today.

But it has absolutely been worth the effort!

So thank you for subscribing, and please join me in saying Happy International Microorganism Day! 🔬🦠

Take today to celebrate everyone who works with microorganisms: microbiologists, plant pathologists, biotechnologists and scientists who have experienced both the excitement of discovery and the persistence behind it, observing, testing, repeating and starting again. Thanks!

(And in case you have ever wondered whether toys can influence a child's future, this microscope certainly did! 😉)

Bacterial canker, caused by Clavibacter michiganensis, is a difficult disease to control in tomato production. A study published in Applied and Environmental Microbiology by researchers at Canada's Institut national de la recherche scientifique identified three bacterial strains that restricted the disease while also supporting plant growth.

The researchers started with more than 500 bacteria already held in the team's collection, isolated from vegetable, fruit and field crops across Quebec, Florida and New York. They tested the isolates for their ability to inhibit the pathogen and for characteristics associated with plant growth. Around 250 showed antagonism on plate, and 32 went forward into experiments with tomato plants.

Three strains produced the strongest results: Pantoea agglomerans SO16PY and two Pseudomonas marginalis sensu lato strains named IRDA16 and SO16PC.

SO16PY provided the strongest protection. It delayed the appearance of disease symptoms by up to seven days and reduced the disease severity score from 85% in infected control plants to 45%. IRDA16 and SO16PC also restricted disease development, reducing severity to 67.5% and 57.5%, respectively. All three strains promoted growth as well, roughly doubling primary root length in vitro, from 3.3 cm in untreated plants to between 6.3 and 6.7 cm.

Compared with the genomes of related bacteria, IRDA16 and SO16PC show a digital DNA-DNA hybridization value close to 69.5%, just under the 70% mark used to separate species. Phylogenomic analysis places them in a distinct lineage, clearly separated from the pathogenic type strain, and the authors propose they represent a new Pseudomonas species.

The genomes also carry groups of genes that may help explain how the two strains interact with plants and other microorganisms. Some are associated with the production of viscosin, a molecule composed of a lipid and a peptide, and others with the production of terpenes.

Molecules of this kind may contribute to plant growth promotion or pathogen suppression, according to the authors. However, the study only identified the genetic capacity to produce them. It did not confirm which molecules were produced during the experiments or establish that any one of them caused the protection observed in tomato plants.

The authors recognize all three as strains able to hold the disease back and help the plant grow at the same time, two of them from a Pseudomonas lineage that had not been described before.

Researchers at Xinjiang Agricultural University developed a solid formulation of Myxococcus fulvus KS01 to control cotton Verticillium wilt. These predatory bacteria were isolated from saline alkaline cotton fields in Yuli County and can form resistant structures called myxospores.

They cultivated KS01 on insect frass mixed with wheat straw. After adjusting the nutrients and fermentation conditions, they produced 6.61 × 10⁷ viable myxospores per gram, 131 times more than the original process.

The formulation achieved 71.9% disease control in greenhouse experiments. In a naturally infested field, control reached 71.2% during square formation and 54.5% during flowering and boll development. The fungicide benziothiazolinone reached 51.4% and 41.4% at the same stages.

Frass and straw with no bacteria reached 44.6% and 35.0% at the same stages, so part of the effect comes from the substrate itself. The authors call the frass a supportive foundation and the productivity of the strain the critical factor, and read the combination as synergy. Treated plots still produced 5,380 kilograms of seed cotton per hectare against 3,577.5 in the untreated control.

The trial was conducted at one location, efficacy declined as the season progressed, and storage stability and performance across regions remain untested.

The authors show that solid state fermentation can increase the production of Myxococcus fulvus KS01 myxospores and turn them into an effective formulation. The resulting agent suppressed Verticillium wilt and increased cotton yield, making it a promising biological control option.

Peat is commonly used to carry rhizobial inoculants, but it is a limited and nonrenewable resource. A study published in the Journal of Soil Science and Plant Nutrition by researchers at Australia's Griffith University tested whether an enriched pinewood biochar could provide a more effective carrier for Bradyrhizobium japonicum CB1809, the soybean strain supplied by the Australian Inoculants Research Group.

The researchers compared peat and biochar formulations containing different combinations of xanthan gum, polyacrylamide, eggshell and mulch hay. The complete formulation performed best, maintaining 95% bacterial survival after 120 days at 28°C and retaining significantly more viable rhizobia than peat.

The formulation was then tested on soybean under three watering regimes. Under severe drought, plants receiving the enriched biochar had 90% more shoot biomass and roots 189% longer than uninoculated plants. Compared with peat, the same plants produced 19.8 nodules against 7.5, fixed 88% more nitrogen and maintained 24% greater nitrogenase activity.

The experiment was conducted in pots, and the precise proportions of the carrier ingredients were not disclosed. Even so, the study shows that improving the environment surrounding an inoculant can extend bacterial survival and translate into stronger nitrogen fixation and plant growth under water stress.