Amazing Paper Written by Two Graduate Students. Go Figure

Now this is a research paper.

In order to get my point across about the previous paper being innovative but lacking technique, I found another research article in the World Microbiology Biotechnology Journal that does things right.It covers the same type pf research with the same type of solubilizing bacteria. 

The papers starts with a very thorough introduction, not only shaping the current study but giving credit to past research that has preceded it. In order to focus the paper, it begins with the basics and then gets down to the gritty details. I will try to do the same.

Rice is an extremely significant crop in Thailand and yields about 85% of the global rice production.

Rice soil in Thailand luckily contains plant growth-promoting rhizobacteria (PGPR) such as N2-fixing

Azospirilla, phosphate-solubilizing bacteria (PSB) and fluorescent bacteria (FB) that help to increase rice yield.  When phosphate fertilizer is applied to the acidic soils in Thailand, the soluble plant phosphate reacts to form aluminum and iron phosphates. This renders approximately 90% of the phosphate applied to the crops unavailable. Although this has been a problem in the short term, it has also created a large reserve of insoluble phosphate that can be freed- which is good news!

It is the goal of this study to find an easy method of assessing plant growth-promoting activity of the rice soil with phosphate-solubilizing bacteria, with a view of trialing any potentially successful inocula.

The method section of this paper is something of pure beauty. I will not bore you with all the details, and why they are so well recorded, but I will include an example below of just how inclusive this section of the paper is:

“After incubation period, the cultures were

harvested by centrifugation at 6,000 rev min-1 for 15 min.

Sterile uninoculated medium served as control. Remaining

phosphate in the culture supernatant was estimated using

the Fiske and Subbarow method (1925), modified culture

supernatant 500 ll was mixed with 500 ll of 10% (w/v)

Trichloroacetic acid in a test tube to which was added 4 ml

of color reagent (1:1:1:2 ratio of 3 M H2SO4/2.5% (w/v)

Ammonium molybdate/10% (w/v) Ascorbic acid and distilled

water) and incubated at room temperature (26 ±

2_C), 15 min. The absorbance of the developing blue color

was measured at 820 using spectrophotometer.”

The method section of this paper also contained a section on how its statistics were run, and with what program. As an undergrad, we were always taught to include this type of information, but having read hundreds of papers, I can safely say a large majority of papers do not include a section for statistical analysis.

The authors of this paper decided to pool the results and discussion into one section of the paper, broken up into subheadings. This was the best way to discuss this paper since so many experiments and assays were performed. It allowed the reader to follow the exact scientific findings and easily connect them to the importance of these findings.

It was found that 216 isolates of phosphate-solubilizing bacteria and 100% of strains solubilized inorganic phosphate on PVK plates. Table 2 is a very simple data table shown below that demonstrates a significant

drop in soluble phosphorus levels over several days due perhaps in part to the inhibitory effect of soluble phosphate. It also shows the ability of these bacteria to solubilize phosphate from different insoluble phosphate forms such as tricalcium phosphate, aluminum phosphate and rock phosphate. Please note that nothing like this was conducted in the previous research of Malboobi - what form the PSBs solubilized from was not even mentioned.

The solubilization of tricalcium phosphate, aluminum phosphate was significant, while solubilization of rock phosphate was very low. The solubilization of rock phosphates depends on their structural complexity

and particle size.

Another additional result this study found that was not covered in previous research was that these bacteria were able to secrete fungal cell wall-degrading enzymes, which would help with the biocontrol potential of selected strains.

The paper wraps up in one clear and concise paragraph. It explains that the characterization and screening of rhizobacteria from rice rhizosphere helped in the selection of various phosphate-solubilizing organisms. Bacteria that are ammonia, catalase and cell wall-degrading enzyme producers are superior strains for use as possible bio-inoculants. There was at least a 22% increase in rice yields with these bacteria.

FINALLY,  the paper ends with some future directions. Field trials with selected strains from this study are now planned!

With a mix of extremely detailed biochemical methodology and a constant focus on the bigger picture, this paper delivers some truly wonderful scientific research.

And to think… it was written by two graduate students. Go figure

Reference 

Chaiharn, M. and Lumyong, S., 2009. Phosphate solubilization potential and stress tolerance of rhizobacteria
from rice soil in Northern Thailand. World. J. Microbiol. Biotechnol., 25, 305–314.