Most scientific writing is written in an objective manner, with little drama or flair. Typically the results are being showcased, not the writing. The purpose of scientific writing is not to entertain; the purpose is to inform. The writing should be simple and easy to understand. The style of the writing itself is relatively formal - the use of slang and the overuse of contractions should be avoided.

Because science and scientific research is supposed to be presented objectively, scientific writing has traditionally been written in a passive voice. The pronouns “I,” “We,” and “They” were typically not used. For example, instead of writing “I used MacConkey agar to isolate the bacterium Escherichia coli,” it is more customary to write, “MacConkey agar was used to isolate the bacterium Escherichia coli.” This is still the rule for Material and Methods, but recently the convention is changing and the active voice is more commonly used in journal articles today (Refer to Day, 1994).

Verb Tense

Most of scientific writing is in the past tense, although there are exceptions. Everything that the researcher has performed is described in past tense. This includes the summary of the experiment performed (the abstract), description of the materials and methods used to perform the experiment, and the results obtained from the experiment. The present tense is reserved for the researcher’s conclusions about the experimental results, conclusions of previous researchers, and any facts that are generally accepted by the scientific field. These are found in the introduction and parts of the discussion.

Although most writing guides stipulate that the tense should be coordinated within a sentence or paragraph, there are exceptions. According to the American Society for Microbiology (ASM) 2001 Instructions to Authors (found in the beginning of every journal of ASM), there are some instances where it is acceptable to vary the tense in a single sentence. The examples given by ASM as acceptable include:

  • “White (3) demonstrated that XYZ cells grow at pH 6.8,”
  • “Figure 2 shows that ABC cells failed to grow at room temperature,”
  • “Air was removed from the chamber and the mice died, which proves that mice require air,”
  • “The values for the ABC cells are statistically significant, indicating that the drug inhibited…”

Microbial Nomenclature

The rules governing the naming of prokaryotes are established by the International Committee on Systematics of Prokaryotes (ICSP). Binary names consisting of genus and a specific epithet (commonly referred to as species) are used for most microorganisms (the exception to this is the viruses, see information below). A species is a binary combination consisting of a genus followed by a specific epithet. In other words, you would never refer to the species without the accompanying genus. The genus name is capitalized and the species is lower case. The names should be italicized or underlined in text. Once the complete name of a microorganism has been written out once, the genus name can be abbreviated to just the capital letter provided there is no confusion with other genera.  Example: Staphylococcus aureus can be written as S. aureus the second time, as long as no other genera in the paper start with the letter “S.” However, the ICSP recommends that the entire name be spelled out again in the summary of any publication.

The designation “sp.” after a genus refers to a single unnamed species, while the designation “spp.” after a genus refers to more than one unnamed species. Example: Salmonella spp. refers to more than one species of Salmonella. In lists that contain a series of species all belonging to the same genus, it is acceptable to name the genus only once, even if the other species have not been mentioned previously. Example: Clostridium tetani, C. botulinum, C. perfringens....

Often bacteria are divided into subspecies, which are indicated by “infrasubspecific subdivisions” such as: biovar (usual abbreviation: bv.), chemoform, chemovar, cultivar (usual abbreviation: cv.), forma specialis (abbreviation: f. sp.), morphovar, pathovar (usual abbreviation: pv.), phagovar, phase, serovar, and state. This is placed, in roman text, before an additional italicized name. Example: Rhizobium leguminosarum biovar viciae. The ICSP does not have rules covering taxa below subspecies, such as for a strain designation, which should follow after the genus and species and may be a combination of letters and numbers. Example: Escherichia coli O157:H7, where O157:H7 designates the particular antigenic strain of E. coli that is being used.

The rules governing the naming of viruses are established by the International Committee on Taxonomy of Viruses (ICTV). The controversy surrounding the naming of viruses is ongoing and unresolved. Viruses are also given a genus and a species, and frequently a strain categorization. However, there are many difficulties in establishing viral species and viral strains. Because of this, the ICTV currently requires that the English common name, rather than a Latinized binomial term, be used to designate a viral species. For example, HIV is classified as family Retroviridae, genus Lentivirus (note the italics), and species Human Immunodeficiency Virus. The virus is then commonly referred to by its species name.

Genetic Nomenclature

(The following information was copied from a website produced by Susan Payne, Associate Professor, Department of Biology, University of Texas at Arlington. The website address is:

Gene names are designated with 3 letters that form a mnemonic descriptive of gene function:  his for histidine biosynthesis. If more than one gene product contributes to a specific function then capital letters are used. For example, 8 genes are involved in histidine biosynthesis hisABCDEFGHI.

An auxotroph that needs histidine to grow would be a his mutant. Thus a his mutant may have mutations in hisA, hisB, hisC etc. The phenotype is His-, or simply His, in comparison to the wild-type organism which would be His+. Note that the phenotype designation is not italicized. The genotype denotes the actual mutation: for example hisA (note that genotype designations are frequently given before the function of the gene product is known). Alleles are different forms of a gene, therefore different mutations in a gene are alleles. Alleles are designated with numbers. Thus hisG251 is different than hisG252. Deletions are noted with the Greek capital letter Delta (D). A D(hisG-hisD) is a mutation encompassing the hisG and hisD genes.

Insertions are designated with ::  Insertions are frequently caused by transposons or phage. Thus a particular Tn10 insertion in the hisG gene might be hisG9425::Tn10. That means that there is a Tn10 insertion into hisG.

Antibiotic sensitivity is referred to as s (sensitive) versus r (resistant). Ampr denotes an ampicillin resistant strain.

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